apache tinkerpop logo

TinkerPop Upgrade Information

This document helps users of Apache TinkerPop™ to understand the changes that come with each software release. It outlines new features, how to resolve breaking changes and other information specific to a release. This document is useful to end-users who are building applications on TinkerPop, but it is equally useful to TinkerPop providers, who build libraries and other systems on the core APIs and protocols that TinkerPop exposes.

These providers include:

  • Graph System Provider

    • Graph Database Provider

    • Graph Processor Provider

  • Graph Driver Provider

  • Graph Language Provider

  • Graph Plugin Provider

TinkerPop 3.5.0

gremlin sleeping beauty

The Sleeping Gremlin: No. 18 Entr’acte symphonique

TinkerPop 3.5.0

Release Date: NOT OFFICIALLY RELEASED YET

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

Gryo Usage

Since the first release of TinkerPop 3.x, Gryo has been the default serialization format for Gremlin Server and Java Driver. It was also used as the default serialization format for Gremlin Console remote connectivity to Gremlin Server. As of this release, Gryo has been replaced as the default by GraphBinary. All packaged configuration files and programmatic defaults have been modified as such.

It is still possible to utilize Gryo as a message serialization format by modifying Gremlin Server configuration files to include the appropriate Gryo configurations. If using Gryo, do not user earlier versions of the driver and server with 3.5.0. Use a 3.5.0 client to connect to a 3.5.0 server. Generally speaking, mixed version combinations will appear to work properly, but problems will likely occur during general course of usage and it is therefore not advisable to take this approach.

For best compatibility between 3.4.x and 3.5.x, please use GraphBinary.

Configuration Upgrade

There is a major breaking change in the use of Configuration objects. Prior to 3.5.0, Configuration objects were from the Apache Commons commons-configuration library, but in this version, they are of commons-configuration2. While this is a breaking change, the fix for most implementations will be quite simple, Simply, change the import statements from:

org.apache.commons.configuration.*

to

org.apache.commons.configuration2.*

It is also worth noting that default list handling in configurations is treated differently. TinkerPop largely disabled the default list handling approach in Configuration 1.x, but if that functionality is still needed, it can be reclaimed by setting the LegacyListDelimiterHandler - details for doing taking this step and other relevant upgrade information can be found in the 2.x Upgrade Documentation.

addV() and null

There was a bit of inconsistency in the handling of null in calls to property() depending on the type of mutation being executed demonstrated as follows in earlier versions:

gremlin> g.V(1).property("x", 1).property("y", null).property("z", 2)
The AddPropertyStep does not have a provided value: AddPropertyStep({key=[y]})
Type ':help' or ':h' for help.
Display stack trace? [yN]N
gremlin> g.addV("test").property("x", 1).property("y", null).property("z", 2)
==>v[13]
gremlin> g.V(13).properties()
==>vp[x->1]
==>vp[z->2]

In this release, this behavior has been altered to become consistent as follows:

gremlin> g.V(1).property("x", 1).property("y", null).property("z", 2)
Property value can not be null
Type ':help' or ':h' for help.
Display stack trace? [yN]n
gremlin> g.addV().property("x", 1).property("y", null).property("z", 2)
Property value can not be null
Type ':help' or ':h' for help.
Display stack trace? [yN]

Remote SideEffects

Remote traversals no longer support the retrieval of remote side-effects. Users must therefore directly return side-effects as part of their query if they need that data. Note that server settings for TraversalOpProcessor, which formerly held the cache for these side-effects, no longer have any effect and can be removed.

Deprecation Removal

The following deprecated classes, methods or fields have been removed in this version:

  • gremlin-core

    • org.apache.tinkerpop.gremlin.process.computer.bulkdumping.BulkDumperVertexProgram

    • org.apache.tinkerpop.gremlin.process.computer.bulkloading.BulkLoader

    • org.apache.tinkerpop.gremlin.process.computer.bulkloading.BulkLoaderVertexProgram

    • org.apache.tinkerpop.gremlin.process.computer.bulkloading.IncrementalBulkLoader

    • org.apache.tinkerpop.gremlin.process.computer.bulkloading.OneTimeBulkLoader

    • org.apache.tinkerpop.gremlin.process.computer.clustering.peerpressure.PeerPressureVertexProgram.Builder#traversal(*)

    • org.apache.tinkerpop.gremlin.process.computer.ranking.pagerank.PageRankVertexProgram.Builder#traversal(*)

    • org.apache.tinkerpop.gremlin.process.computer.ranking.pagerank.PageRankVertexProgram.Builder#vertexCount()

    • org.apache.tinkerpop.gremlin.process.computer.traversal.step.map.PageRankVertexProgramStep.modulateBy(*)

    • org.apache.tinkerpop.gremlin.process.computer.traversal.step.map.PageRankVertexProgramStep.modulateTimes()

    • org.apache.tinkerpop.gremlin.process.computer.traversal.step.map.PeerPressureVertexProgramStep.modulateBy(*)

    • org.apache.tinkerpop.gremlin.process.computer.traversal.step.map.PeerPressureVertexProgramStep.modulateTimes()

    • org.apache.tinkerpop.gremlin.process.remote.traversal.AbstractRemoteTraversalSideEffects

    • org.apache.tinkerpop.gremlin.process.remote.traversal.EmbeddedRemoteTraversalSideEffects

    • org.apache.tinkerpop.gremlin.process.remote.traversal.RemoteTraversalSideEffects

    • org.apache.tinkerpop.gremlin.process.remote.traversal.RemoteTraversal#getSideEffects()

    • org.apache.tinkerpop.gremlin.process.traversal.Order.decr

    • org.apache.tinkerpop.gremlin.process.traversal.Order.incr

    • org.apache.tinkerpop.gremlin.process.traversal.TraversalSource#withRemote(*)

    • org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversalSource#withRemote(*)

    • org.apache.tinkerpop.gremlin.process.traversal.step.map.PropertyMapStep(Traversal.Admin, boolean, PropertyType, String…​)

    • org.apache.tinkerpop.gremlin.process.traversal.step.map.PropertyMapStep#isIncludeTokens()

    • org.apache.tinkerpop.gremlin.structure.util.star.StarGraph#builder()

    • org.apache.tinkerpop.gremlin.structure.util.star.StarGraph.Builder#create()

  • gremlin-driver

    • org.apache.tinkerpop.gremlin.driver.Tokens#ARGS_SCRIPT_EVAL_TIMEOUT

    • org.apache.tinkerpop.gremlin.driver.Cluster.Builder#keyCertChainFile(String)

    • org.apache.tinkerpop.gremlin.driver.Cluster.Builder#keyFile(String)

    • org.apache.tinkerpop.gremlin.driver.Cluster.Builder#keyPassword(String)

    • org.apache.tinkerpop.gremlin.driver.Cluster.Builder#trustCertificateChainFile(String)

    • org.apache.tinkerpop.gremlin.driver.remote.DriverRemoteTraversalSideEffects

    • org.apache.tinkerpop.gremlin.driver.remote.DriverRemoteTraversal#getSideEffects()

  • gremlin-server

    • org.apache.tinkerpop.gremlin.server.Settings.scriptEvaluationTimeout

    • org.apache.tinkerpop.gremlin.server.Settings.SslSettings.keyCertChainFile

    • org.apache.tinkerpop.gremlin.server.Settings.SslSettings.keyFile

    • org.apache.tinkerpop.gremlin.server.Settings.SslSettings.keyPassword

    • org.apache.tinkerpop.gremlin.server.Settings.SslSettings.trustCertificateChainFile

    • org.apache.tinkerpop.gremlin.server.ResponseHandlerContext

    • org.apache.tinkerpop.gremlin.server.op.AbstractEvalOpProcessor.evalOpInternal(ResponseHandlerContext, Supplier, BindingSupplier)

    • org.apache.tinkerpop.gremlin.server.op.AbstractOpProcessor.generateMetaData(ChannelHandlerContext, RequestMessage, ResponseStatusCode, Iterator)

    • org.apache.tinkerpop.gremlin.server.op.AbstractOpProcessor.handleIterator(ResponseHandlerContext, Iterator)

    • org.apache.tinkerpop.gremlin.server.op.AbstractOpProcessor.makeFrame(ChannelHandlerContext, RequestMessage, MessageSerializer, boolean, List, ResponseStatusCode, Map)

    • org.apache.tinkerpop.gremlin.server.op.AbstractOpProcessor.makeFrame(Context, RequestMessage, MessageSerializer, boolean, List, ResponseStatusCode, Map)

    • org.apache.tinkerpop.gremlin.server.op.AbstractOpProcessor.makeFrame(ResponseHandlerContext, RequestMessage, MessageSerializer, boolean, List, ResponseStatusCode, Map)

    • org.apache.tinkerpop.gremlin.server.op.AbstractOpProcessor.makeFrame(ResponseHandlerContext, RequestMessage, MessageSerializer, boolean, List, ResponseStatusCode, Map, Map)

    • org.apache.tinkerpop.gremlin.server.util.SideEffectIterator

  • neo4j-gremlin

    • org.apache.tinkerpop.gremlin.neo4j.structure.Neo4jGraph#getTrait()

    • org.apache.tinkerpop.gremlin.neo4j.structure.Neo4jGraph#CONFIG_META_PROPERTIES

    • `org.apache.tinkerpop.gremlin.neo4j.structure.Neo4jGraph#CONFIG_MULTI_PROPERTIES `

    • org.apache.tinkerpop.gremlin.neo4j.structure.trait.MultiMetaNeo4jTrait

    • org.apache.tinkerpop.gremlin.neo4j.structure.trait.NoMultiNoMetaNeo4jTrait

    • org.apache.tinkerpop.gremlin.neo4j.structure.trait.Neo4jTrait

Certain elements of the API were not or could not be deprecated in prior versions and were simply renamed for this release:

  • org.apache.tinkerpop.gremlin.driver.message.ResponseStatusCode#SERVER_ERROR_SCRIPT_EVALUATION became SERVER_ERROR_EVALUATION

Upgrading for Provider

Graph System Providers

AbstractOpProcessor API Change

The generateMetaData() method was removed as it was deprecated in a previous version. There already was a preferred method called generateResultMetaData() that took an extra Settings parameter. To fix compilation issues simply replace implementations of the generateMetaData() method with generateResultMetaData(). Gremlin Server has only been calling generateResultMetaData() since the deprecation, so this correction should be straightforward.

StoreStep and AggregateStep

Note that StoreStep has been renamed to AggregateLocalStep and AggregateStep has been renamed to AggregateGlobalStep. The renaming is important to consider if any custom TraversalStrategies have been written that rely on the old step names.

TraversalOpProcessor Side-effects

TraversalOpProcessor no longer holds a cache of side-effects and more generally the entire side-effect protocol has been removed and is no longer supported in the server or drivers.

TinkerPop 3.5.0

Upgrading for Users

Upgrade Neo4j

Refer to Neo4j 3.4 Upgrade FAQ for guide on how to upgrade from the previous 3.2.3 version. For example, configuration setting dbms.allow_format_migration is now dbms.allow_upgrade.

TinkerPop 3.4.0

avant gremlin

Avant-Gremlin Construction #3 for Theremin and Flowers

TinkerPop 3.4.4

Release Date: October 14, 2019

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

Python GraphBinary

There is now support for GraphBinary in Python. As with Java, it remains a working but experimental format that is still under evaluation. This new serializer can be used by first ensuring that it is available on the server and then configuring the connection as follows:

from gremlin_python.driver.serializer import GraphBinarySerializersV1
gremlin_server_url = "ws://172.17.0.2:45940/gremlin"
remote_conn = DriverRemoteConnection(gremlin_server_url, 'g',
                                     message_serializer=GraphBinarySerializersV1())
g = Graph().traversal().withRemote(remote_conn)

elementMap() Step

Since graph elements (i.e. Vertex, Edge, and VertexProperty) are returned from remote sources as references (i.e. without properties), one of the more common needs for Gremlin users is the ability to easily return a Map representation of the elements that they are querying. Typically, such transformations are handled by valueMap():

gremlin> g.V().has('person','name','marko').valueMap(true)
==>[id:1,label:person,name:[marko],age:[29]]
gremlin> g.V().has('person','name','marko').valueMap().by(unfold())
==>[name:marko,age:29]

or by way of project():

gremlin> g.V().has('person','name','marko').
......1>   project('name','age','vid','vlabel').
......2>     by('name').
......3>     by('age').
......4>     by(id).
......5>     by(label)
==>[name:marko,age:29,vid:1,vlabel:person]

While valueMap() works reasonably well for Vertex and VertexProperty transformations it does less well for Edge as it fails to include incident vertices:

gremlin> g.E(11).valueMap(true)
==>[id:11,label:created,weight:0.4]

This limitation forces a fairly verbose use of project() for what is a reasonably common requirement:

gremlin> g.E(12).union(valueMap(true),
......1>               project('inV','outV','inVLabel','outVLabel').
......2>                 by(inV().id()).
......3>                 by(outV().id()).
......4>                 by(inV().label()).
......5>                 by(outV().label())).unfold().
......6>               group().
......7>                 by(keys).
......8>                 by(select(values))
==>[inV:3,id:12,inVLabel:software,weight:0.2,outVLabel:person,label:created,outV:6]

By introducing elementMap()-step, there is now a single step that covers the most common transformation requirements for all three graph elements:

gremlin> g.V().has('person','name','marko').elementMap()
==>[id:1,label:person,name:marko,age:29]
gremlin> g.V().has('person','name','marko').elementMap('name')
==>[id:1,label:person,name:marko]
gremlin> g.V().has('person','name','marko').properties('name').elementMap()
==>[id:0,key:name,value:marko]
gremlin> g.E(11).elementMap()
==>[id:11,label:created,IN:[id:3,label:software],OUT:[id:4,label:person],weight:0.4]

TinkerPop 3.4.3

Release Date: August 5, 2019

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

Deprecated store()

The store()-step and aggregate()-step do the same thing in different ways, where the former is lazy and the latter is eager in the side-effect collection of objects from the traversal. The different behaviors can be thought of as differing applications of Scope where global is eager and local is lazy. As a result, there is no need for both steps when one will do.

As of 3.4.3, store(String) is now deprecated in favor of aggregate(Scope, String) where the Scope should be set to local to ensure the same functionality as store(). Note that aggregate('x') is the same as aggregate(global,'x').

Deprecate Gryo in Gremlin Server

Gryo is now deprecated as a serialization format for Gremlin Server, however, it is still configured as a default option in the sample configuration files packaged with the server. The preferred serialization option should now be GraphBinary. Note that Gremlin Console is now configured to use GraphBinary by default.

Upgrading for Providers

Graph Driver Providers

Gremlin Server Test Configuration

Gremlin Server has a test configuration built into its Maven build process which all integration tests and Gremlin Language Variants use to validate their operations. While this approach has worked really well for test automation within Maven, there are often times where it would be helpful to simply have Gremlin Server running with that configuration. This need is especially true when developing Gremlin Language Variants which is something that is done outside of the JVM.

This release introduces a Docker script that will start Gremlin Server with this test configuration. It can be started with:

docker/gremlin-server.sh

Once started, it is then possible to run GLV tests directly from a debugger against this instance which should hopefully reduce development friction.

TinkerPop 3.4.2

Release Date: May 28, 2019

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

Per Request Options

In 3.4.0, the notion of RequestOptions were added so that users could have an easier way to configure settings on individual requests made through the Java driver. While that change provided a way to set those configurations for script based requests, it didn’t include options to make those settings in a Traversal submitted via Bytecode. In this release those settings become available via with() step on the TraversalSource as follows:

GraphTraversalSource g = traversal().withRemote(conf);
List<Vertex> vertices = g.with(RemoteConnection.PER_REQUEST_TIMEOUT, 500).V().out("knows").toList()

Gremlin Console Timeout

The Gremlin Console timeout that is set by :remote config timeout x was client-side only in prior versions, which meant that if the console timeout was less than the server timeout the client would timeout but the server might still be processing the request. Similarly, a longer timeout on the console would not change the server and the timeout would occur sooner than expected. These discrepancies often led to confusion.

As of 3.4.0, the Java Driver API allowed for timeout settings to be more easily passed per request, so the console was modified for this current version to pass the console timeout for each remote submission thus yielding more consistent and intuitive behavior.

Upgrading for Providers

Graph System Providers

Warnings

It is now possible to pass warnings over the Gremlin Server protocol using a warnings status attribute. The warnings are expected to be a string value or a List of string values which can be consumed by the user or tools that check for that status attribute. Note that Gremlin Console is one such tool that will respond to this status attribute - it will print the messages to the console as they are detected when doing remote script submissions.

Graph Driver Providers

GraphBinary API Change

In GraphBinary serialization, Java write() and writeValue() from TypeSerializer<T> interface now take a Netty’s ByteBuf instance instead of an ByteBufAllocator, that way the same buffer instance gets reused during the write of a message. Additionally, we took the opportunity to remove the unused parameter from ResponseMessageSerializer.

TinkerPop 3.4.1

Release Date: March 18, 2019

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

Mix SPARQL and Gremlin

In the initial release of sparql-gremlin it was only possible to execute a SPARQL query and have it translate to Gremlin. Therefore, it was only possible to write a query like this:

gremlin> g.sparql("SELECT ?name ?age WHERE { ?person v:name ?name . ?person v:age ?age }")
==>[name:marko,age:29]
==>[name:vadas,age:27]
==>[name:josh,age:32]
==>[name:peter,age:35]
gremlin> g.sparql("SELECT * WHERE { }")
==>v[1]
==>v[2]
==>v[3]
==>v[4]
==>v[5]
==>v[6]

In this release, however, it is now possible to further process that result with Gremlin steps:

gremlin> g.sparql("SELECT ?name ?age WHERE { ?person v:name ?name . ?person v:age ?age }").select("name")
==>marko
==>vadas
==>josh
==>peter
gremlin> g.sparql("SELECT * WHERE { }").out("knows").values("name")
==>vadas
==>josh

Upgrading for Providers

Graph Database Providers

GraphBinary Serializer Changes

In GraphBinary serialization, Java write() and writeValue() from TypeSerializer<T> interface now take a Netty’s ByteBuf instance instead of an ByteBufAllocator, that way the same buffer instance gets reused during the write of a message. Additionally, we took the opportunity to remove the unused parameter from ResponseMessageSerializer.

TinkerPop 3.4.0

Release Date: January 2, 2019

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

sparql-gremlin

The sparql-gremlin module is a SPARQL to Gremlin compiler, which allows SPARQL to be executed over any TinkerPop-enabled graph system.

graph = TinkerFactory.createModern()
g = graph.traversal(SparqlTraversalSource)
g.sparql("""SELECT ?name ?age
            WHERE { ?person v:name ?name . ?person v:age ?age }
            ORDER BY ASC(?age)""")

Gremlin.NET Driver Improvements

The Gremlin.NET driver now uses request pipelining. This allows connections to be reused for different requests in parallel which should lead to better utilization of connections. The ConnectionPool now also has a fixed size whereas it could previously create an unlimited number of connections. Each Connection can handle up to MaxInProcessPerConnection requests in parallel. If this limit is reached for all connections, then a NoConnectionAvailableException is thrown which makes this a breaking change.

These settings can be set as properties on the ConnectionPoolSettings instance that can be passed to the GremlinClient.

Indexing of Collections

TinkerPop 3.4.0 adds a new index()-step, which allows users to transform simple collections into index collections or maps.

gremlin> g.V().hasLabel("software").values("name").fold().
......1>   order(local).
......2>   index().unfold()
==>[lop,0]
==>[ripple,1]
gremlin> g.V().hasLabel("person").values("name").fold().
......1>   order(local).by(decr).
......2>   index().
......3>     with(WithOptions.indexer, WithOptions.map)
==>[0:vadas,1:peter,2:marko,3:josh]

Modulation of valueMap()

The valueMap() step now supports by and with modulation, which also led to the deprecation of valueMap(true) overloads.

by() Modulation

With the help of the by() modulator valueMap() result values can now be adjusted, which is particularly useful to turn multi-/list-values into single values.

gremlin> g.V().hasLabel("person").valueMap()
==>[name:[marko],age:[29]]
==>[name:[vadas],age:[27]]
==>[name:[josh],age:[32]]
==>[name:[peter],age:[35]]
gremlin> g.V().hasLabel("person").valueMap().by(unfold())
==>[name:marko,age:29]
==>[name:vadas,age:27]
==>[name:josh,age:32]
==>[name:peter,age:35]
with() Modulation

The with() modulator can be used to include certain tokens (id, label, key and/or value).

The old way (still valid, but deprecated):

gremlin> g.V().hasLabel("software").valueMap(true)
==>[id:10,label:software,name:[gremlin]]
==>[id:11,label:software,name:[tinkergraph]]
gremlin> g.V().has("person","name","marko").properties("location").valueMap(true)
==>[id:6,key:location,value:san diego,startTime:1997,endTime:2001]
==>[id:7,key:location,value:santa cruz,startTime:2001,endTime:2004]
==>[id:8,key:location,value:brussels,startTime:2004,endTime:2005]
==>[id:9,key:location,value:santa fe,startTime:2005]

The new way:

gremlin> g.V().hasLabel("software").valueMap().with(WithOptions.tokens)
==>[id:10,label:software,name:[gremlin]]
==>[id:11,label:software,name:[tinkergraph]]
gremlin> g.V().has("person","name","marko").properties("location").valueMap().with(WithOptions.tokens)
==>[id:6,key:location,value:san diego,startTime:1997,endTime:2001]
==>[id:7,key:location,value:santa cruz,startTime:2001,endTime:2004]
==>[id:8,key:location,value:brussels,startTime:2004,endTime:2005]
==>[id:9,key:location,value:santa fe,startTime:2005]

Furthermore, now there’s a finer control over which of the tokens should be included:

gremlin> g.V().hasLabel("software").valueMap().with(WithOptions.tokens, WithOptions.labels)
==>[label:software,name:[gremlin]]
==>[label:software,name:[tinkergraph]]
gremlin> g.V().has("person","name","marko").properties("location").valueMap().with(WithOptions.tokens, WithOptions.values)
==>[value:san diego,startTime:1997,endTime:2001]
==>[value:santa cruz,startTime:2001,endTime:2004]
==>[value:brussels,startTime:2004,endTime:2005]
==>[value:santa fe,startTime:2005]

As shown above, the support of the with() modulator for valueMap() makes the valueMap(boolean) overload superfluous, hence this overload is now deprecated. This is a breaking API change, since valueMap() will now always yield instances of type Map<Object, Object>. Prior this change only the valueMap(boolean) overload yielded Map<Object, Object> objects, valueMap() without the boolean parameter used to yield instances of type Map<String, Object>.

Predicate Number Comparison

In previous versions within() and without() performed strict number comparisons; that means these predicates did not only compare number values, but also the type. This was inconsistent with how other predicates (like eq, gt, etc.) work. All predicates will now ignore the number type and instead compare numbers only based on their value.

Old behavior:

gremlin> g.V().has("age", eq(32L))
==>v[4]
gremlin> g.V().has("age", within(32L, 35L))
gremlin>

New behavior:

gremlin> g.V().has("age", eq(32L))
==>v[4]
gremlin> g.V().has("age", within(32L, 35L))
==>v[4]
==>v[6]

ReferenceElementStrategy

Gremlin Server has had some inconsistent behavior in the serialization of the results it returns. Remote traversals based on Gremlin bytecode always detach returned graph elements to "reference" (i.e. removes properties and only include the id and label), but scripts would detach graph elements and include the properties. For 3.4.0, TinkerPop introduces the ReferenceElementStrategy which can be configured on a GraphTraversalSource to always detach to "reference".

gremlin> graph = TinkerFactory.createModern()
==>tinkergraph[vertices:6 edges:6]
gremlin> g = graph.traversal().withStrategies(ReferenceElementStrategy.instance())
==>graphtraversalsource[tinkergraph[vertices:6 edges:6], standard]
gremlin> v = g.V().has('person','name','marko').next()
==>v[1]
gremlin> v.class
==>class org.apache.tinkerpop.gremlin.structure.util.reference.ReferenceVertex
gremlin> v.properties()
gremlin>

The packaged initialization scripts that come with Gremlin Server now pre-configure the sample graphs with this strategy to ensure that both scripts and bytecode based requests over any protocol (HTTP, websocket, etc) and serialization format all return a "reference". To revert to the old form, simply remove the strategy in the initialization script.

It is recommended that users choose to configure their GraphTraversalSource instances with ReferenceElementStrategy as working with "references" only is the recommended method for developing applications with TinkerPop. In the future, it is possible that ReferenceElementStrategy will be configured by default for all graphs on or off Gremlin Server, so it would be best to start utilizing it now and grooming existing Gremlin and related application code to account for it.

Text Predicates

Gremlin now supports simple text predicates on top of the existing P predicates. Both, the new TextP text predicates and the old P predicates, can be chained using and() and or().

gremlin> g.V().has("person","name", containing("o")).valueMap()
==>[name:[marko],age:[29]]
==>[name:[josh],age:[32]]
gremlin> g.V().has("person","name", containing("o").and(gte("j").and(endingWith("ko")))).valueMap()
==>[name:[marko],age:[29]]

Changed Infix Behavior

The infix notation of and() and or() now supports an arbitrary number of traversals and ConnectiveStrategy produces a traversal with proper AND and OR semantics.

Input: a.or.b.and.c.or.d.and.e.or.f.and.g.and.h.or.i

*BEFORE*
Output: or(a, or(and(b, c), or(and(d, e), or(and(and(f, g), h), i))))

*NOW*
Output: or(a, and(b, c), and(d, e), and(f, g, h), i)

Furthermore, previous versions failed to apply 3 or more and() steps using the infix notation, this is now fixed.

gremlin> g.V().has("name","marko").and().has("age", lt(30)).or().has("name","josh").and().has("age", gt(30)).and().out("created")
==>v[1]
==>v[4]

GraphBinary

GraphBinary is a new language agnostic, network serialization format designed to replace Gryo and GraphSON. At this time it is only available on the JVM, but support will be added for other languages in upcoming releases. The serializer has been configured in Gremlin Server’s packaged configuration files. The serializer can be configured using the Java driver as follows:

Cluster cluster = Cluster.build("localhost").port(8182).
                          serializer(Serializers.GRAPHBINARY_V1D0).create();
Client client = cluster.connect();
List<Result> r = client.submit("g.V().has('person','name','marko')").all().join();

Status Attributes

The Gremlin Server protocol allows for status attributes to be returned in responses. These attributes were typically for internal use, but were designed with extensibility in mind so that providers could place return their own attributes to calling clients. Unfortunately, unless the client was being used with protocol level requests (which wasn’t convenient) those attributes were essentially hidden from view. As of this version however, status attributes are fully retrievable for both successful requests and exceptions.

with() Step

This version of TinkerPop introduces the with()-step to Gremlin. It isn’t really a step but is instead a step modulator. This modulator allows the step it is modifying to accept configurations that can be used to alter the behavior of the step itself. A good example of its usage is shown with the revised syntax of the pageRank()-step which now uses with() to replace the old by() options:

g.V().hasLabel('person').
  pageRank().
    with(PageRank.edges, __.outE('knows')).
    with(PageRank.propertyName, 'friendRank').
  order().
    by('friendRank',desc).
  valueMap('name','friendRank')

A similar change was made for peerPressure()-step:

g.V().hasLabel('person').
  peerPressure().
    with(PeerPressure.propertyName, 'cluster').
  group().
    by('cluster').
    by('name')

Note that the by() modulators still work, but should be considered deprecated and open for removal in a future release where breaking changes are allowed.

shortestPath() Step

Calculating the shortest path between vertices is a common graph use case. While the traversal to determine a shortest path can be expressed in Gremlin, this particular problem is common enough that the feature has been encapsulated into its own step, demonstrated as follows:

gremlin> g.withComputer().V().has('name','marko').
......1>   shortestPath().with(ShortestPath.target, has('name','peter'))
==>[v[1],v[3],v[6]]

connectedComponent() Step

In prior version of TinkerPop, it was recommended that the identification of Connected Component instances in a graph be computed by way of a reasonably complex bit of Gremlin that looked something like this:

g.V().emit(cyclicPath().or().not(both())).repeat(both()).until(cyclicPath()).
  path().aggregate("p").
  unfold().dedup().
  map(__.as("v").select("p").unfold().
         filter(unfold().where(eq("v"))).
         unfold().dedup().order().by(id).fold()).
  dedup()

The above approach had a number of drawbacks that included a large execution cost as well as incompatibilities in OLAP. To simplify usage of this commonly use graph algorithm, TinkerPop 3.4.0 introduces the connectedComponent() step which reduces the above operation to:

g.withComputer().V().connectedComponent()

It is important to note that this step does require the use of a GraphComputer to work, as it utilizes a VertexProgram behind the scenes.

io() Step

There have been some important changes to IO operations for reading and writing graph data. The use of Graph.io() has been deprecated to further remove dependence on the Graph (Structure) API for users and to extend these basic operations to GLV users by making these features available as part of the Gremlin language.

It is now possible to simply use Gremlin:

graph = ...
g = graph.traversal()
g.io(someInputFile).read().iterate()
g.io(someOutputFile).write().iterate()

While io()-step is still single-threaded for OLTP style loading, it can be utilized in conjunction with OLAP which internally uses CloneVertexProgram and therefore any graph InputFormat or OutputFormat can be configured in conjunction with this step for parallel loads of large datasets.

It is also worth noting that the io()-step may be overridden by graph providers to utilize their native bulk-loading features, so consult the documentation of the implementation being used to determine if there are any improved efficiencies there.

Per Request Options

The Java driver now allows for various options to be set on a per-request basis via new overloads to submit() that accept RequestOption instances. A good use-case for this feature is to set a per-request override to the scriptEvaluationTimeout so that it only applies to the current request.

Cluster cluster = Cluster.open();
Client client = cluster.connect();
RequestOptions options = RequestOptions.build().timeout(500).create();
List<Result> result = client.submit("g.V()", options).all().get();

min() max() and Comparable

Previously min() and max() were only working for numeric values. This has been changed and these steps can now operate over any Comparable value. The common workaround was the combination of order().by() and limit() as shown here:

gremlin> g.V().values('name').order().by().limit(1)      // workaround for min()
==>josh
gremlin> g.V().values('name').order().by(decr).limit(1)  // workaround for max()
==>vadas

Any attempt to use min() or max() on non-numeric values lead to an exception:

gremlin> g.V().values('name').min()
java.lang.String cannot be cast to java.lang.Number
Type ':help' or ':h' for help.
Display stack trace? [yN]

With the changes in this release these kind of queries became a lot easier:

gremlin> g.V().values('name').min()
==>josh
gremlin> g.V().values('name').max()
==>vadas

Nested Loop Support

Traversals now support nesting of repeat() loops.

These can now be used to repeat another traversal while in a looped context, either inside the body of a repeat() or in its step modifiers (until() or emit()).

gremlin> g.V().repeat(__.in('traverses').repeat(__.in('develops')).emit()).emit().values('name')
==>stephen
==>matthias
==>marko

EventStrategy API

There were some minor modifications to how EventStrategy is constructed and what can be expected from events raised from the addition of new properties.

With respect to the change in terms of EventStrategy construction, the detach() builder method formerly took a Class as an argument and that Class was meant to be one of the various "detachment factories" or null. That approach was a bit confusing, so that signature has changed to detach(EventStrategy.Detachment) where the argument is a more handy enum of detachment options.

As for the changes related to events themselves, it is first worth noting that the previously deprecated vertexPropertyChanged(Vertex, Property, Object, Object…​) on MutationListener has been removed for what should have originally been the correct signature of vertexPropertyChanged(Vertex, VertexProperty, Object, Object…​). In prior versions when this method and its related edgePropertyChanged() and vertexPropertyPropertyChanged() were triggered by way of the addition of a new property a "fake" property was included with a null value for the "oldValue" argument to these methods (as it did not exist prior to this event). That was a bit awkward to reason about when dealing with that event. To make this easier, the event now raises with a KeyedVertexProperty or KeyedProperty instance, which only contains a property key and no value in them.

Reducing Barrier Steps

The behavior of min(), max(), mean() and sum() has been modified to return no result if there’s no input. Previously these steps yielded the internal seed value:

gremlin> g.V().values('foo').min()
==>NaN
gremlin> g.V().values('foo').max()
==>NaN
gremlin> g.V().values('foo').mean()
==>NaN
gremlin> g.V().values('foo').sum()
==>0

These traversals will no longer emit a result. Note, that this also affects more complex scenarios, e.g. if these steps are used in by() modulators:

gremlin> g.V().group().
......1>   by(label).
......2>   by(outE().values("weight").sum())
==>[software:0,person:3.5]

Since software vertices have no outgoing edges and thus no weight values to sum, software will no longer show up in the result. In order to get the same result as before, one would have to add a coalesce()-step:

gremlin> g.V().group().
......1>   by(label).
......2>   by(outE().values("weight").sum())
==>[person:3.5]
gremlin> g.V().group().
......1>   by(label).
......2>   by(coalesce(outE().values("weight"), constant(0)).sum())
==>[software:0,person:3.5]

Order of select() Scopes

The order of select scopes has been changed to: maps, side-effects, paths. Previously the order was: side-effects, maps, paths - which made it almost impossible to select a specific map entry if a side-effect with the same name existed.

The following snippets illustrate the changed behavior:

gremlin> g.V(1).
......1>   group("a").
......2>     by(__.constant("a")).
......3>     by(__.values("name")).
......4>   select("a")
==>[a:marko]
gremlin> g.V(1).
......1>   group("a").
......2>     by(__.constant("a")).
......3>     by(__.values("name")).
......4>   select("a").select("a")
==>[a:marko]

Above is the old behavior; the second select("a") has no effect, it selects the side-effect a again, although one would expect to get the map entry a. What follows is the new behavior:

gremlin> g.V(1).
......1>   group("a").
......2>     by(__.constant("a")).
......3>     by(__.values("name")).
......4>   select("a")
==>[a:marko]
gremlin> g.V(1).
......1>   group("a").
......2>     by(__.constant("a")).
......3>     by(__.values("name")).
......4>   select("a").select("a")
==>marko

GraphSON BulkSet

In earlier versions of TinkerPop, BulkSet was coerced to a List for GraphSON which was convenient in that it didn’t add a new data type to support, but inconvenient in that it meant that certain process tests were not consistent in terms of how they ran and the benefits of the BulkSet were "lost" in that the "bulk" was being resolved server side. With the addition of BulkSet as a GraphSON type the "bulk" is now resolved on the client side by the language variant. How that resolution occurs depends upon the language variant. For Java, there is a BulkSet object which maintains that structure sent from the server. For the other variants, the BulkSet is deserialized to a List form which results in a much larger memory footprint than what is contained the BulkSet.

Python Bindings

Bindings were formerly created using a Python 2-tuple as a bit of syntactic sugar, but all other language variants used an explicit Bindings object which gremlin-python already had in place. To make all work variants behave consistently, the 2-tuple syntax has been removed in favor of the explicit Bindings.of() option.

g.V(Bindings.of('id',1)).out('created').map(lambda: ("it.get().value('name').length()", "gremlin-groovy")).sum()

Deprecation and Removal

This section describes newly deprecated classes, methods, components and patterns of usage as well as which previously deprecated features have been officially removed or repurposed.

Moving of RemoteGraph

RemoteGraph was long ago deprecated in favor of withRemote(). It became even less useful with the introduction of the AnonymousTraversalSource concept in 3.3.5. It’s only real use was for testing remote bytecode based traversals in the test suite as the test suite requires an actual Graph object to function properly. As such, RemoteGraph has been moved to gremlin-test. It should no longer be used in any capacity besides that.

Removal of Giraph Support

Support for Giraph has been removed as of this version. There were a number of reasons for this decision which were discussed in the community prior to taking this step. Users should switch to Spark for their OLAP based graph-computing needs.

Removal of Rebindings Options

The "rebindings" option is no longer supported for clients. It was deprecated long ago at 3.1.0. The server will not respond to them on any channel - websockets, nio or HTTP. Use the "aliases" option instead.

gremlin-server.sh -i Removal

The -i option for installing dependencies in Gremlin Server was long ago deprecated and has now been removed. Please use install as its replacement going forward.

Deprecation Removal

The following deprecated classes, methods or fields have been removed in this version:

  • gremlin-core

    • org.apache.tinkerpop.gremlin.jsr223.ImportCustomizer#GREMLIN_CORE

    • org.apache.tinkerpop.gremlin.process.remote.RemoteGraph - moved to gremlin-test

    • org.apache.tinkerpop.gremlin.process.remote.RemoteConnection.submit(Traversal)

    • org.apache.tinkerpop.gremlin.process.remote.RemoteConnection.submit(Bytecode)

    • org.apache.tinkerpop.gremlin.process.remote.traversal.strategy.decoration.RemoteStrategy#identity()

    • org.apache.tinkerpop.gremlin.process.traversal.TraversalEngine

    • org.apache.tinkerpop.gremlin.process.traversal.engine.*

    • org.apache.tinkerpop.gremlin.process.traversal.strategy.decoration.PartitionStrategy.Builder#addReadPartition(String)

    • org.apache.tinkerpop.gremlin.process.traversal.strategy.decoration.SubgraphStrategy.Builder#edgeCriterion(Traversal)

    • org.apache.tinkerpop.gremlin.process.traversal.strategy.decoration.SubgraphStrategy.Builder#vertexCriterion(Traversal)

    • org.apache.tinkerpop.gremlin.process.traversal.step.map.LambdaCollectingBarrierStep.Consumers

    • org.apache.tinkerpop.gremlin.process.traversal.step.util.HasContainer#makeHasContainers(String, P)

    • org.apache.tinkerpop.gremlin.process.traversal.step.util.event.MutationListener#vertexPropertyChanged(Vertex, Property, Object, Object…​)

    • org.apache.tinkerpop.gremlin.structure.Element.Exceptions#elementAlreadyRemoved(Class, Object)

    • org.apache.tinkerpop.gremlin.structure.Graph.Exceptions#elementNotFound(Class, Object)

    • org.apache.tinkerpop.gremlin.structure.Graph.Exceptions#elementNotFound(Class, Object, Exception)

  • gremlin-driver

    • org.apache.tinkerpop.gremlin.driver.Client#rebind(String)

    • org.apache.tinkerpop.gremlin.driver.Client.ReboundClusterdClient

    • org.apache.tinkerpop.gremlin.driver.Tokens#ARGS_REBINDINGS

  • gremlin-groovy

    • org.apache.tinkerpop.gremlin.groovy.jsr223.GremlinGroovyScriptEngine.close() - no longer implements AutoCloseable

  • gremlin-server

    • org.apache.tinkerpop.gremlin.server.GraphManager#getGraphs()

    • org.apache.tinkerpop.gremlin.server.GraphManager#getTraversalSources()

    • org.apache.tinkerpop.gremlin.server.Settings#serializedResponseTimeout

    • org.apache.tinkerpop.gremlin.server.Settings.AuthenticationSettings#className

    • org.apache.tinkerpop.gremlin.server.handler.OpSelectorHandler(Settings, GraphManager, GremlinExecutor, ScheduledExecutorService)

    • org.apache.tinkerpop.gremlin.server.op.AbstractOpProcessor#makeFrame(ChannelHandlerContext, RequestMessage, MessageSerializer serializer, boolean, List, ResponseStatusCode code)

  • hadoop-graph

    • org.apache.tinkerpop.gremlin.hadoop.structure.HadoopConfiguration#getGraphInputFormat()

    • org.apache.tinkerpop.gremlin.hadoop.structure.HadoopConfiguration#getGraphOutputFormat()

Please see the javadoc deprecation notes or upgrade documentation specific to when the deprecation took place to understand how to resolve this breaking change.

Deprecated GraphSONMessageSerializerGremlinV2d0

The GraphSONMessageSerializerGremlinV2d0 serializer is now analogous to GraphSONMessageSerializerV2d0 and therefore redundant. It has technically always been equivalent in terms of functionality as both serialized to the same format (i.e. GraphSON 2.0 with embedded types). It is no longer clear why these two classes were established this way, but it does carry the negative effect where multiple serializer versions could not be bound to Gremlin Server’s HTTP endpoint as the MIME types conflicted on application/json. By simply making both message serializers support application/json and application/vnd.gremlin-v2.0+json, it then became possible to overcome that limitation. In short, prefer use of GraphSONMessageSerializerV2d0 when possible.

Note that this is a breaking change in the sense that GraphSONMessageSerializerV2d0 will no longer set the header of requests messages to application/json. As a result, older versions of Gremlin Server not configured with GraphSONMessageSerializerGremlinV2d0 will not find a deserializer to match the request.

Removed groovy-sql Dependency

Gremlin Console and Gremlin Server no longer include groovy-sql. If you depend on groovy-sql, you can install it in Gremlin Console or Gremlin Server using the plugin system.

Console:

:install org.codehaus.groovy groovy-sql 2.5.2

Server:

bin/gremlin-server.sh install org.codehaus.groovy groovy-sql 2.5.2

If your project depended on groovy-sql transitively, simply include it in your project’s build file (e.g. maven: pom.xml).

Upgrading for Providers

Graph Database Providers

io() Step

The new io()-step that was introduced provides some new changes to consider. Note that Graph.io() has been deprecated and users are no longer instructed to utilize that method. It is not yet decided when that method will be removed completely, but given the public nature of it and the high chance of common usage, it should be hanging around for some time.

As with any step in Gremlin, it is possible to replace it with a more provider specific implementation that could be more efficient. Developing a TraversalStrategy to do this is encouraged, especially for those graph providers who might have special bulk loaders that could be abstracted by this step. Examples of this are already shown with HadoopGraph which replaces the simple single-threaded loader with CloneVertexProgram. Graph providers are encouraged to use the with() step to capture any necessary configurations required for their underlying loader to work. Graph providers should not feel restricted to graphson, gryo and graphml formats either. If a graph supports CSV or some custom graph specific format, it shouldn’t be difficult to gather the configurations necessary to make that available to users.

Caching Graph Features

For graph implementations that have expensive creation times, it can be time consuming to run the TinkerPop test suite as each test run requires a Graph instance even if the test is ultimately ignored becaue it doesn’t pass the feature checks. To possibly help alleviate this problem, the GraphProvider interface now includes this method:

public default Optional<Graph.Features> getStaticFeatures() {
    return Optional.empty();
}

This method can be implemented to return a cacheable set of features for a Graph generated from that GraphProvider. Assuming this method is faster than the cost of creating a new Graph instance, the test suite should execute significantly faster depending on how many tests end up being ignored.

Configuring Interface

There were some changes to interfaces that were related to Step. A new Configuring interface was added that was helpful in the implementation of the with()-step modulator. This new interface extends the Parameterizing interface (which moved to the org.apache.tinkerpop.gremlin.process.traversal.step package with the other step interfaces) and in turn is extended by the Mutating interface. Making this change meant that the Mutating.addPropertyMutations() method could be removed in favor of the new Configuring.configure() method.

All of the changes above basically mean, that if the Mutating interface was being used in prior versions, the addPropertyMutations() method simply needs to be changed to configure().

OptionsStrategy

OptionsStrategy is a TraversalStrategy that makes it possible for users to set arbitrary configurations on a Traversal. These configurations can be used by graph providers to allow for traversal-level configurations to be accessible to their custom steps. A user would write something like:

g.withStrategies(OptionsStrategy.build().with("specialLimit", 10000).create()).V();

The OptionsStrategy is really only the carrier for the configurations and while users can choose to utilize that more verbose method for constructing it shown above, it is more elegantly constructed as follows using with()-step:

g.with("specialLimit", 10000)).V();

The graph provider could then access that value of "specialLimit" in their custom step (or elsewhere) as follows:

OptionsStrategy strategy = this.getTraversal().asAdmin().getStrategies().getStrategy(OptionsStrategy.class).get();
int specialLimit = (int) strategy.getOptions().get("specialLimit");
Removed hadoop-gremlin Test Artifact

The hadoop-gremlin module no longer generates a test jar that can be used as a test dependency in other modules. Generally speaking, that approach tends to be a bad practice and can cause build problems with Maven that aren’t always obvious to troubleshoot. With the removal of giraph-gremlin for 3.4.0, it seemed even less useful to have this test artifact present. All tests are still present. The follow provides a basic summary of how this refactoring occurred:

  • A new AbstractFileGraphProvider was created in gremlin-test which provided a lot of the features that HadoopGraphProvider was exposing. Both HadoopGraphProvider and SparkHadoopGraphProvider extend from that class now.

  • ToyIoRegistry and related classes were moved to gremlin-test.

  • The various tests that validated capabilities of Storage have been moved to spark-gremlin and are part of those tests now. Obviously, that makes those tests specific to Spark testing now. If that location creates a problem for some reason, that decision can be revisited at some point.

TraversalEngine Moved

The TraversalEngine interface was deprecated in 3.2.0 along with all related methods that used it and classes that implemented it. It was replaced by the Computer interface and provided a much nicer way to plug different implementations of Computer into a traversal. TraversalEngine was never wholly removed however as it had some deep dependencies in the inner workings of the test suite. That infrastructure has largely remained as is until now.

As of 3.4.0, TraversalEngine is no longer in gremlin-core and can instead be found in gremlin-test as it is effectively a "test-only" component and serves no other real function. As explained in the javadocs going back to 3.2.0, providers should implement the Computer class and use that instead. At this point, graph providers should have long ago moved to the Computer infrastructure as methods for constructing a TraversalSource with a TraversalEngine were long ago removed.

Upsert Graph Feature

Some Graph implementations may be able to offer upsert functionality for vertices and edges, which can help improve usability and performance. To help make it clear to users that a graph operates in this fashion, the supportsUpsert() feature has been added to both Graph.VertexFeatures and Graph.EdgeFeatures. By default, both of these methods will return false.

Should a provider wish to support this feature, the behavior of addV() and/or addE() should change such that when a vertex or edge with the same identifier is provided, the respective step will insert the new element if that value is not present or update an existing element if it is found. The method by which the provider "identifies" an element is completely up to the capabilities of that provider. In the most simple fashion, a graph could simply check the value of the supplied T.id, however graphs that support some form of schema will likely have other methods for determining whether or not an existing element is present.

The extent to which TinkerPop tests "upsert" is fairly narrow. Graph providers that choose to support this feature should consider their own test suites carefully to ensure appropriate coverage.

TypeTranslator Changes

The TypeTranslator experienced a change in its API and GroovyTranslator a change in expectations.

TypeTranslator now implements BiFunction and takes the graph traversal source name as an argument along with the object to translate. This interface is implemented by default for Groovy with GroovyTranslator.DefaultTypeTranslator which encapsulates all the functionality of what GroovyTranslator formerly did by default. To provide customize translation, simply extend the DefaultTypeTranslator and override the methods.

GroovyTranslator now expects that the TypeTranslator provide to it as part of its of() static method overload is "complete" - i.e. that it provides all the functionality to translate the types passed to it. Thus, a "complete" TypeTranslator is one that does everything that DefaultTypeTranslator does as a minimum requirement. Therefore, the extension model described above is the easiest way to get going with a custom TypeTranslator approach.

Graph Driver Providers

Deprecation Removal in RemoteConnection

The two deprecated synchronous submit() methods on the RemoteConnection interface have been removed, which means that RemoteConnection implementations will need to implement submitAsync(Bytecode) if they have not already done so.

TinkerPop 3.3.0

gremlin mozart

Gremlin Symphony #40 in G Minor

TinkerPop 3.3.9

Release Date: October 14, 2019

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

ReservedKeysVerificationStrategy

ReservedKeysVerificationStrategy is a new VerificationStrategy that can be used to help prevent traversals from adding property keys that are protected. They may be protected as a result of the key being a reserved keyword of the underlying graph system or they key may simply violate some standard conventions.

gremlin> g.withStrategies(ReservedKeysVerificationStrategy.build().throwException().create()).addV('person').property("id",123)
The provided traversal contains a AddVertexStartStep that is setting a property key to a reserved word: id
Type ':help' or ':h' for help.
Display stack trace? [yN]

Javascript ResponseError

Gremlin Javascript now enables more robust error handling by way of a ResponseError which provides access to more information from the server. Specifically, it includes the statusMessage and statusCode which were formerly packed into the Error.message property, which meant that the error message string had to be parsed if there was a need to take a specific action based on that information. The ResponseError also includes the statusAttributes which is a Map object that will typically incorporate server exceptions and stackTrace keys, but could also include provider specific error information.

The original error messaging has remained unchanged and therefore users who were message parsing should not expect changes in behavior, however, future versions will eliminate the "overuse" of the Error.message property, so it is advised that users update their code to take advantage of the ResponseError features.

Java Driver NoHostAvailableException

Expect a NoHostAvailableException rather than a more generic TimeoutException if the Java driver is unable to connect to a Host. This sort of failure can occur in a number of different scenarios, but can often occur when there are configuration problems with authentication and SSL, preventing the connection to the Host to be established.

Deprecated scriptEvaluationTimeout

The scriptEvaluationTimeout controls the length of time a request is processed by Gremlin Server (or at its core, the GremlinExecutor). Of course, with the introduction of bytecode-based requests many versions ago, this naming has failed to make complete sense in more recent times. Therefore, scriptEvaluationTimeout has been deprecated and replaced by evaluationTimeout. Both configurations are still respected, but it is advised that users switch to evaluationTimeout as scriptEvaluationTimeout will be removed in a later version.

Note that when configuring Gremlin Server’s evaluationTimeout that the scriptEvaluationTimeout should be set to -1 (the default) or else it will use that value in its initialization of the server and ignore the evaluationTimeout.

TinkerPop 3.3.8

Release Date: August 5, 2019

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

Branch Steps Accept Predicates and Traversals

Prior to this version, branch steps (in particular BranchStep and ChooseStep) could only handle constant values and Pick tokens. Starting in this version, these steps will also accept predicates and traversals as show in the example below.

gremlin> g = TinkerFactory.createModern().traversal()
==>graphtraversalsource[tinkergraph[vertices:6 edges:6], standard]
gremlin> g.V().hasLabel("person").
......1>   group().
......2>     by("name").
......3>     by(branch(values("age")).
......4>          option(29, constant("almost old")).
......5>          option(__.is(32), constant("looks like josh")).
......6>          option(lt(29), constant("pretty young")).
......7>          option(lt(35), constant("younger than peter")).
......8>          option(gte(30), constant("pretty old")).
......9>          option(none, constant("mysterious")).fold()).
.....10>   unfold()
==>peter=[pretty old]
==>vadas=[pretty young, younger than peter]
==>josh=[looks like josh, younger than peter, pretty old]
==>marko=[almost old, younger than peter]

Python DateTime

With GraphSON, the g:Date is meant to represent a millisecond-precision offset from the unix epoch, but earlier version of Gremlin Python were using the timezone of the local system to handle serialization and deserialization, thus resulting in incorrect conversion. This issue is now resolved. It may be necessary to remove workarounds that have been introduced to combat this problem.

JavaScript withComputer()

Gremlin-Javascript now supports withComputer() syntax, which means that it is now possible in Javascript to utilize Gremlin steps that require a GraphComputer to execute (e.g. pageRank() and peerPressure()).

JavaScript and .NET hasNext()

There is now greater consistency across Gremlin Language Variants with hasNext() support added to both JavaScript and .NET. Note that in .NET, the proper method name follows C# capitalization semantics and is referred to as HasNext().

Deprecated getSideEffects()

Traversal.getSideEffects() has been deprecated for purposes of external calls by end-users. While the method is still present TinkerPop no longer guarantees its existence in future versions or consistency of its behavior, especially for Gremlin Language Variants and remote traversal execution. If this method is currently in use to gather side-effect results after traversal execution, please change such code to use cap()-step. For example, code like this:

gremlin> t = g.V().hasLabel('person').aggregate('p').out('created')
==>v[3]
==>v[5]
==>v[3]
==>v[3]
gremlin> t.getSideEffects().get('p')
==>v[1]
==>v[2]
==>v[4]
==>v[6]

should be converted to something like:

gremlin> g.V().hasLabel('person').aggregate('p').out('created').union(fold(),cap('p'))
==>[v[3],v[3],v[3],v[5]]
==>[v[1],v[2],v[4],v[6]]

EventStrategy

Prior TinkerPop 3.3.6 EventStrategy did not work with multi-properties. The EventStrategy behavior for single-valued properties has not changed; if a property is added to a multi-valued VertexProperty, then a VertexPropertyChangedEvent will be now be fired. The arguments passed to the event depend on the cardinality type.

Cardinality.list

Since properties will always be added and never be overwritten, the old property passed to the change event will always be an empty property.

Cardinality.set

The old property passed to the change event will be empty if no other property with the same value exists, otherwise, it will be the existing property.

TinkerPop 3.3.7

Release Date: May 28, 2019

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

JavaScript DSL Pattern

Gremlin DSL developers had to rely on monkey patching to build a Domain Specific Language in JavaScript. With this latest version, the process is a bit more elegant and largely handled by extending existing core classes of Gremlin-JavaScript which is a bit more in-line with other language variant patterns for DSL development.

Gremlin Console Interrupt

There are occasions where a traversal (or other evaluation) takes longer than expected to complete. Common examples of these situations typically include:

  • Accidentally executing g.V() (i.e. full graph scan) on a very large graph as an OLTP style traversal.

  • Not terminating a repeat() properly which results in an infinite loop.

  • Bad data might create a cycle in the graph where one wasn’t expected.

  • Failing to properly bound a traversal’s path through one or more supernodes.

In earlier versions, the only option was to kill the Gremlin Console (typically with ctrl+c), but as of this version ctrl+c will be intercepted and attempt to interrupt whatever process is currently executing.

Removed gperfutils Dependency

Gremlin Console included references to:

<dependency>
    <groupId>org.gperfutils</groupId>
    <artifactId>gbench</artifactId>
</dependency>
<dependency>
    <groupId>org.gperfutils</groupId>
    <artifactId>gprof</artifactId>
</dependency

to provide some benchmarking and profiling tools for the Utilities Plugin. Neither project is well maintained at this point and given that TinkerPop has moved past the versions of Groovy that are supported by these tools it doesn’t make sense to retain the dependencies. Users who wish to continue to use these tools can obviously do so still by manually adding the dependencies to the Gremlin Console or with the following command:

gremlin> :install org.gperfutils gbench <version>
gremlin> :install org.gperfutils gprof <version>

and then import the appropriate classes and methods to use.

Upgrading for Providers

Graph Database Providers

Detection of Anti-Patterns

This release adds a strategy named EdgeLabelVerificationStrategy. The strategy will not be added by default to the traversal source, however, providers can add it explicitly to encourage (or enforce) users to always specify at least one edge label. EdgeLabelVerificationStrategy can be configured to either throw an exception if no edge label was specified, log a warning or do both.

gremlin> // throw an exception if edge label was not specified
gremlin> g = TinkerFactory.createModern().traversal().withStrategies(EdgeLabelVerificationStrategy.build().throwException().create())
==>graphtraversalsource[tinkergraph[vertices:6 edges:6], standard]
gremlin> g.V(1).out('knows')
==>v[2]
==>v[4]
gremlin> g.V(1).out()
The provided traversal contains a vertex step without any specified edge label: VertexStep(OUT,vertex)
Type ':help' or ':h' for help.
Display stack trace? [yN]
gremlin> // log a warning if edge label was not specified (Log4j has to be configured properly)
gremlin> g = TinkerFactory.createModern().traversal().withStrategies(EdgeLabelVerificationStrategy.build().logWarning().create())
==>graphtraversalsource[tinkergraph[vertices:6 edges:6], standard]
gremlin> g.V(1).out('knows')
==>v[2]
==>v[4]
gremlin> g.V(1).out()
WARN  org.apache.tinkerpop.gremlin.process.traversal.strategy.verification.EdgeLabelVerificationStrategy  - The provided traversal contains a vertex step without any specified edge label: VertexStep(OUT,vertex)
==>v[3]
==>v[2]
==>v[4]

TinkerPop 3.3.6

Release Date: March 18, 2019

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

Anti-Patterns Documentation

The Gremlin Recipes documentation now has a new section which discusses anti-patterns in Gremlin. Its subsections detail commonly seen approaches to the Gremlin language which can lead to poorly written and/or under-performing traversals. The new Anti-Patterns Section can be found here.

TinkerPop 3.3.5

Release Date: January 2, 2019

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

AnonymousTraversalSource

The AnonymousTraversalSource provides for a more unified syntax for TraversalSource construction by placing greater user emphasis on the creation of the source rather than the Graph it is connected to. It has a number of different static traversal() methods available and when imported as:

import static org.apache.tinkerpop.gremlin.process.traversal.AnonymousTraversalSource.traversal;

allows TraversalSource construction syntax such as:

gremlin> g = traversal().withGraph(TinkerFactory.createModern())
==>graphtraversalsource[tinkergraph[vertices:6 edges:6], standard]
gremlin> g = traversal().withRemote('conf/remote-graph.properties')
==>graphtraversalsource[emptygraph[empty], standard]
gremlin> g = traversal().withRemote(DriverRemoteConnection.using('localhost',8182))
==>graphtraversalsource[emptygraph[empty], standard]

Typically, this syntax is used for "remote" traversal construction for bytecode based requests, but has the option to bind a local Graph instance to it as well. It doesn’t save much typing to do so obviously, so it may not be best used in that situation. Python, Javascript and .NET have similar syntax.

Bytecode Command

The Gremlin Console now has a new :bytecode command to help users work more directly with Gremlin bytecode. The command is more of a debugging tool than something that would be used for every day purposes. It is sometimes helpful to look at Gremlin bytecode directly and the process for viewing it in human readable format is not a single step process. It is also not immediately clear how to convert bytecode to a Gremlin string. The :bytecode command aims to help with both of these issues:

gremlin> g = TinkerFactory.createModern().traversal()
==>graphtraversalsource[tinkergraph[vertices:6 edges:6], standard]
gremlin> :bytecode from g.V().out('knows')  1
==>{"@type":"g:Bytecode","@value":{"step":[["V"],["out","knows"]]}}
gremlin> :bytecode translate g {"@type":"g:Bytecode","@value":{"step":[["V"],["out","knows"]]}} 2
==>g.V().out("knows")

Configurable Class Map Cache

The "class map" cache in Gremlin Server (specifically the GremlinGroovyScriptEngine) that holds compiled scripts is now fully configurable via the GroovyCompilerGremlinPlugin.classMapCacheSpecification.

RangeStep Optimizing Strategy

A new strategy named EarlyLimitStrategy was added. The strategy will try to find a better spot for any RangeStep, which is as early as possible in the traversal. If possible it will also merge multiple RangeStep`s into a single one by recalculating the range for the first step and removing the second. If it turns out that the merge of two steps won’t produce a valid range (an empty result), then the `EarlyLimitStrategy will remove the RangeStep`s and insert a `NoneStep instead.

This strategy is particularly useful when a provider implementation generates the queries to the underlying database. By making sure that the ranges are applied as early as possible, we can ensure that the underlying database is only asked for the least amount of data necessary to continue the traversal evaluation.

Upgrading for Providers

Graph Database Providers

OptOut on GraphProvider

It is not uncommon for those utilizing the TinkerPop test suite to have multiple configurations of their graph under test. The multiple configurations typically manifest as multiple GraphProvider implementations which supply the different configurations to test. It is sometimes the case, that a particular Graph configuration cannot support all of the tests in the suite at which point some less than straightforward approaches to dealing with that present as solutions.

It has always been possible to apply an OptOut annotation to a Graph instance, to avoid a particular test execution. It is now possible to apply that same OptOut to a GraphProvider instance for that same purpose. Hopefully, this feature will make multiple configuration testing easier.

TinkerPop 3.3.4

Release Date: October 15, 2018

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

Introducing Order.asc and Order.desc

The Order enum originally introduced incr for ascending order and decr for descending order. It’s not clear why they were named this way when common querying parlance would call for asc and desc for those respective cases. Note that incr and decr have not been removed - just deprecated and thus marked for future removal. Prefer asc and desc going forward when writing Gremlin and look to update existing code using the deprecated values.

TimedInterrupt

In Gremlin Server, it is best not to use the timedInterrupt option on GroovyCompilerGremlinPlugin because it can compete with the scriptEvaluationTimeout setting and produce a different error path. Simply rely on scriptEvaluationTimeout as it covers both script evaluation time and result iteration time.

TinkerPop 3.3.3

Release Date: May 8, 2018

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

Credential DSL Changes

The Credential DSL has been modified to work as a standard Java-based Gremlin DSL. The now deprecated old approach used a "graph wrapping" style that was developed long before the recommended method for building DSLs was published. Under this new model, the DSL is initialized via traversal as follows:

CredentialTraversalSource credentials = graph.traversal(CredentialTraversalSource.class)
credentials.user("stephen","password").iterate()
credentials.users("stephen").valueMap().next()
credentials.users().count().next()
credentials.users("stephen").drop().iterate()

TinkerPop 3.3.2

Release Date: April 2, 2018

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

Gremlin Python Sets

Graph traversals that return a Set from Java are now coerced to a List in Python. This change ensures that Python results match Java results for the same traversal. It is possible to see this problem in prior versions of gremlin-python where a Set of numbers of different types are returned. In Java, a set of:

[1,1.0d,2,2.0d]

would be deserialized to the following in Python:

[1,2]

Now that the Java Set is coerced to a List in Gremin Python, the Java Set can be fully represented. Users who require a Set will need to manually convert their List to a Set.

TinkerPop 3.3.1

Release Date: December 17, 2017

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

Gremlin Python path()

There was a bug in GraphSON 3.0 serialization that prevented proper handling of results contain Path object. As a result, traversals that used and returned results from the path()-step in Python would return unusable results, but did not actually cause an exception condition. This problem is now resolved.

Added math()-step for Scientific Traversal Computing

GraphTraversal.math(String) was added. This step provides scientific calculator capabilities to a Gremlin traversal.

gremlin> g.V().as('a').out('knows').as('b').math('a + b').by('age')
==>56.0
==>61.0
gremlin> g.V().as('a').out('created').as('b').
......1>   math('b + a').
......2>     by(both().count().math('_ + 100')).
......3>     by('age')
==>132.0
==>133.0
==>135.0
==>138.0
gremlin> g.withSack(1).V(1).repeat(sack(sum).by(constant(1))).times(10).emit().sack().math('sin _')
==>0.9092974268256817
==>0.1411200080598672
==>-0.7568024953079282
==>-0.9589242746631385
==>-0.27941549819892586
==>0.6569865987187891
==>0.9893582466233818
==>0.4121184852417566
==>-0.5440211108893698
==>-0.9999902065507035

Changed Typing on from() and to()

The from() and to()-steps of GraphTraversal have a Traversal<E,Vertex> overload. The E has been changed to ? in order to reduce < >-based coersion in strongly type Gremlin language variants.

addV(traversal) and addE(traversal)

The GraphTraversal and GraphTraversalSource methods of addV() and addE() have been extended to support dynamic label determination upon element creation. Both these methods can take a Traversal<?, String> where the first String returned by the traversal is used as the label of the respective element.

gremlin> g = TinkerFactory.createModern().traversal()
==>graphtraversalsource[tinkergraph[vertices:6 edges:6], standard]
gremlin> g.addV(V().has('name','marko').label()).
           property('name','stephen')
==>v[13]
gremlin> g.V().has('name','stephen').valueMap(true)
==>[name:[stephen],label:person,id:13]
gremlin> g.V().has('name','stephen').
           addE(V().hasLabel('software').inE().label()).
             to(V().has('name','lop'))
==>e[15][13-created->3]
gremlin> g.V().has('name','stephen').outE().valueMap(true)
==>[label:created,id:15]
gremlin>

PageRankVertexProgram

There were two major bugs in the way in which PageRank was being calculated in PageRankVertexProgram. First, teleportation energy was not being distributed correctly amongst the vertices at each round. Second, terminal vertices (i.e. vertices with no outgoing edges) did not have their full gathered energy distributed via teleportation.

For users upgrading, note that while the relative rank orders will remain "the same," the actual PageRank values will differ from prior TinkerPop versions.

VERTEX  iGRAPH    TINKERPOP
marko   0.1119788 0.11375485828040575
vadas   0.1370267 0.14598540145985406
lop     0.2665600 0.30472082661863686
josh    0.1620746 0.14598540145985406
ripple  0.2103812 0.1757986539008437
peter   0.1119788 0.11375485828040575

Normalization preserved through computation:

0.11375485828040575 +
0.14598540145985406 +
0.30472082661863686 +
0.14598540145985406 +
0.1757986539008437 +
0.11375485828040575
==>1.00000000000000018

Two other additions to PageRankVertexProgram were provided as well.

  1. It now calculates the vertex count and thus, no longer requires the user to specify the vertex count.

  2. It now allows the user to leverage an epsilon-based convergence instead of having to specify the number of iterations to execute.

IO Defaults

While 3.3.0 released Gryo 3.0 and GraphSON 3.0 and these versions were defaulted in a number of places, it seems that some key defaults were missed. Specifically, calls to Graph.io(graphson()) and Graph.io(gryo()) were still using the old versions. The defaults have now been changed to ensure 3.0 is properly referenced in those cases.

Upgrade Neo4j

See Neo4j’s 3.2 Upgrade FAQ for a complete guide on how to upgrade from the previous 2.3.3 version. Also note that many of the configuration settings have changed from neo4j 2x to 3x

In particular, these properties referenced in TinkerPop documentation and configuration were renamed:

Neo4j 2.3 (TinkerPop <= 3.3.0) Neo4j 3.2 (TinkerPop 3.3.1)

node_auto_indexing

dbms.auto_index.nodes.enabled

relationship_auto_indexing

dbms.auto_index.relationships.enabled

ha.cluster_server

ha.host.coordination

ha.server

ha.host.data

Upgrading for Providers

Important
It is recommended that providers also review all the upgrade instructions specified for users. Many of the changes there may prove important for the provider’s implementation.

Graph Database Providers

IO Version Check

In the Graph.io() method, providers are to bootstrap the Io instance returned with their own custom serializers typically provided through a custom IoRegistry instance. Prior to this change it was not possible to easily determine the version of Io that was expected (nor was it especially necessary as TinkerPop didn’t have breaking format changes between versions). As of 3.3.0 however, there could be IO test incompatibilities for some providers who need to register a different IoRegistry instance depending on the version the user wants.

To allow for that check, the Io interface now has the following method:

public <V> boolean requiresVersion(final V version);

which allows the graph provider to check if a specific GryoVersion or GraphSONVersion is required. Using that information, the provider could then assign the right IoRegistry to match that.

TinkerPop 3.3.0

Release Date: August 21, 2017

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

Packaged Data Files

TinkerPop has always packaged sample graphs with its zip distributions. As of 3.3.0, the distributions will only include Gryo 3.0, GraphSON 3.0 and GraphML (which is unversioned) files. Other versions are not included, but could obviously be generated using the IO API directly.

GraphTraversal Has-Methods Re-Organized

GraphTraversal.hasXXX(), where XXX is Id, Label, Key, Value, was faulty in that they relied on calling an intermediate method for flattening Object[] arguments and thus, yielding a non 1-to-1 correspondence between GraphTraversal and Bytecode. This has been remedied. Most users will not notice this change. Perhaps only some users that may use Java reflection over GraphTraversal might have a simple problem.

Changes to IO

Gryo 3.0

With Gryo, TinkerPop skips version 2.0 and goes right to 3.0 (to maintain better parity with GraphSON versioning). Gryo 3.0 fixes a number of inconsistencies with Gryo 1.0 and hopefully marks a point where Gryo is better versioned over time. Gryo 3.0 is not compatible with Gryo 1.0 and is now the default version of Gryo exposed by TinkerPop in Gremlin Server and IO.

It isn’t hard to switch back to use of Gryo 1.0 if necessary. Here is the approach for writing an entire graph:

Graph graph = TinkerFactory.createModern();
GryoMapper mapper = graph.io(IoCore.gryo()).mapper().version(GryoVersion.V1_0).create()
try (OutputStream os = new FileOutputStream("tinkerpop-modern.json")) {
    graph.io(IoCore.gryo()).writer().mapper(mapper).create().writeGraph(os, graph)
}

final Graph newGraph = TinkerGraph.open();
try (InputStream stream = new FileInputStream("tinkerpop-modern.json")) {
    newGraph.io(IoCore.gryo()).reader().mapper(mapper).create().readGraph(stream, newGraph);
}

Gremlin Server configurations don’t include Gryo 1.0 by default:

serializers:
  - { className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV3d0, config: { ioRegistries: [org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerIoRegistryV3d0] }}             # application/vnd.gremlin-v3.0+gryo
  - { className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV3d0, config: { serializeResultToString: true }}                                                                       # application/vnd.gremlin-v3.0+gryo-stringd
  - { className: org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerV3d0, config: { ioRegistries: [org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerIoRegistryV3d0] }}         # application/json

but adding an entry as follows will add it back:

serializers:
  - { className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV1d0, config: { ioRegistries: [org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerIoRegistryV1d0] }}             # application/vnd.gremlin-v1.0+gryo
  - { className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV3d0, config: { ioRegistries: [org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerIoRegistryV3d0] }}             # application/vnd.gremlin-v3.0+gryo
  - { className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV3d0, config: { serializeResultToString: true }}                                                                       # application/vnd.gremlin-v3.0+gryo-stringd
  - { className: org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerV3d0, config: { ioRegistries: [org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerIoRegistryV3d0] }}         # application/json

To use Gryo 1.0 with the Java driver, just specify the 1.0 serializer directly:

GryoMapper.Builder builder = GryoMapper.build().
        version(GryoVersion.V1_0).
        addRegistry(TinkerIoRegistryV1d0.instance());
Cluster cluster = Cluster.build().serializer(GryoMessageSerializerV1d0(builder));
GraphSON 3.0

GraphSON 3.0 finishes what GraphSON 2.0 began by taking the extra step to include the following types: g:Map, g:List and g:Set. With these types it is now possible to get expected Gremlin results in GLVs just as one would if using Java. This is especially true of the g:Map type, which allows non-string keys values, something not allowed in regular JSON maps. This allows for common traversals like g.V().groupCount() to work, where the traversal groups on a Vertex or some other complex object.

Note that GraphSON 3.0 does not have an option to be without types. This was a feature of 1.0 and 2.0, but it is no longer supported. There is little point to such a feature as we see more movement toward GLVs, which require types, and less usage of scripts with custom parsing of results.

Both TinkerGraph and Gremlin Server have been defaulted to work with GraphSON 3.0. For TinkerGraph this means that the following commands:

Graph graph = TinkerFactory.createModern();
graph.io(IoCore.graphson()).writeGraph("tinkerpop-modern.json");

final Graph newGraph = TinkerGraph.open();
newGraph.io(IoCore.graphson()).readGraph("tinkerpop-modern.json");

will write and read GraphSON 3.0 format rather than 1.0. To use 1.0 (or 2.0 for that matter) format simply set the version() on the appropriate builder methods:

Graph graph = TinkerFactory.createModern();
GraphSONMapper mapper = graph.io(IoCore.graphson()).mapper().version(GraphSONVersion.V1_0).create()
try (OutputStream os = new FileOutputStream("tinkerpop-modern.json")) {
    graph.io(IoCore.graphson()).writer().mapper(mapper).create().writeGraph(os, graph)
}

final Graph newGraph = TinkerGraph.open();
try (InputStream stream = new FileInputStream("tinkerpop-modern.json")) {
    newGraph.io(IoCore.graphson()).reader().mapper(mapper).create().readGraph(stream, newGraph);
}

For Gremlin Server, this change means that the application/json mime type no longer returns GraphSON 1.0 without type embedding. Instead, Gremlin Server will return GraphSON 3.0 with partial types enabled (i.e. which is equivalent to application/vnd.gremlin-v3.0+json). The serializers section the sample Gremlin Server YAML files now typically look like this:

serializers:
  - { className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV3d0, config: { ioRegistries: [org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerIoRegistryV3d0] }}             # application/vnd.gremlin-v3.0+gryo
  - { className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV3d0, config: { serializeResultToString: true }}                                                                       # application/vnd.gremlin-v3.0+gryo-stringd
  - { className: org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerV3d0, config: { ioRegistries: [org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerIoRegistryV1d0] }}         # application/json

It is possible to bring back the original configuration for application/json by changing the last entry as follows:

  - { className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV3d0, config: { ioRegistries: [org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerIoRegistryV3d0] }}             # application/vnd.gremlin-v3.0+gryo
  - { className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV3d0, config: { serializeResultToString: true }}                                                                       # application/vnd.gremlin-v3.0+gryo-stringd
  - { className: org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerV1d0, config: { ioRegistries: [org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerIoRegistryV1d0]  }}        # application/json

Graphite and Ganglia

Graphite and Ganglia are no longer packaged with the Gremlin Server distribution. They are considered optional dependencies and therefore must be installed manually by the user.

SelectStep Defaults to Pop.last

SelectStep and SelectOneStep (select()) are the only Scoping steps that default to Pop.mixed as their labeled path selection criteria. All other steps, like match(), where() and dedup(), use Pop.last. In order to better enable optimizations around total Pop.last traversals, the select()-steps now default to Pop.last. Most users will not notice a difference as it is rare for repeated labels to be used in practice. However, formal backwards compatibility is possible as outlined below.

Assuming that x is not a Pop argument:

  1. Change all select(x,y,z) calls to selectV3d2(x,y,z) calls.

  2. Change all select(x,y,z)-step calls to select(Pop.mixed,x,y,z).

If an explicit Pop argument is provided, then no changes are required.

OptionalStep and Side-Effects

The optional()-step was previously implemented using ChooseStep. However, if the optional branch contained side-effects, then unexpected behaviors can emerge. Thus, a potential backwards compatibility issue arises if side-effects were being used in optional(). However, the behavior would be unpredictable so this backwards incompatibility is desirable.

Gremlin Console Initialization

It is no longer possible to intialize the Gremlin Console with a script without use of -e. In other words, prior versions allowed:

bin/gremlin.sh gremlin.groovy

Such a command must now be written as:

bin/gremlin.sh -i gremlin.groovy

GraphTraversal valueMap() Signature Updated

GraphTraversal.valueMap(includeTokens,propertyKeys…​) now returns a Map<Object,E> to account for the presence of T.id or T.label if you pass true to it.

HADOOP_GREMLIN_LIBS and Spark

The TinkerPop reference documentation has always mentioned that the gremlin-spark /lib directory needed to be added to HADOOP_GREMLIN_LIBS environment variable. In reality, that was not truly necessary. With Spark 1.x having gremlin-spark in HADOOP_GREMLIN_LIBS hasn’t been a problem, but Spark 2.0 introduces a check for duplicate jars on the path which will cause job initialization to fail. As a result, going forward with TinkerPop 3.3.0, the gremlin-spark lib directory should not be included in HADOOP_GREMLIN_LIBS.

Deprecation Removal

The following deprecated classes, methods or fields have been removed in this version:

  • giraph-gremlin

    • org.apache.tinkerpop.gremlin.giraph.groovy.plugin.GiraphGremlinPlugin

  • gremlin-console

    • org.apache.tinkerpop.gremlin.console.Console(String)

    • org.apache.tinkerpop.gremlin.console.ConsoleImportCustomizerProvider

    • org.apache.tinkerpop.gremlin.console.plugin.*

    • org.apache.tinkerpop.gremlin.console.groovy.plugin.DriverGremlinPlugin

    • org.apache.tinkerpop.gremlin.console.groovy.plugin.DriverRemoteAcceptor

    • org.apache.tinkerpop.gremlin.console.groovy.plugin.GephiGremlinPlugin

    • org.apache.tinkerpop.gremlin.console.groovy.plugin.UtilitiesGremlinPlugin

  • gremlin-core

    • org.apache.tinkerpop.gremlin.jsr223.CoreGremlinModule

    • org.apache.tinkerpop.gremlin.jsr223.CoreGremlinPlugin#INSTANCE

    • org.apache.tinkerpop.gremlin.jsr223.GremlinModule

    • org.apache.tinkerpop.gremlin.jsr223.SingleGremlinScriptEngineManager#getInstance()

    • org.apache.tinkerpop.gremlin.jsr223.GremlinScriptEngineManager#addModule(GremlinModule)

    • org.apache.tinkerpop.gremlin.jsr223.console.PluginAcceptor

    • org.apache.tinkerpop.gremlin.process.traversal.TraversalSource.Builder

    • org.apache.tinkerpop.gremlin.process.traversal.util.ConnectiveP(P…​)

    • org.apache.tinkerpop.gremlin.process.traversal.util.AndP(P…​)

    • org.apache.tinkerpop.gremlin.process.traversal.util.OrP(P…​)

    • org.apache.tinkerpop.gremlin.process.traversal.util.TraversalScriptFunction

    • org.apache.tinkerpop.gremlin.process.traversal.util.TraversalScriptHelper

    • org.apache.tinkerpop.gremlin.process.traversal.Order.keyIncr

    • org.apache.tinkerpop.gremlin.process.traversal.Order.valueIncr

    • org.apache.tinkerpop.gremlin.process.traversal.Order.keyDecr

    • org.apache.tinkerpop.gremlin.process.traversal.Order.valueIncr

    • org.apache.tinkerpop.gremlin.process.traversal.dsl.GraphTraversal.mapKeys()

    • org.apache.tinkerpop.gremlin.process.traversal.dsl.GraphTraversal.mapValues()

    • org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversal#addV(Object…​)

    • org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversal#addE(Direction, String, String, Object…​)

    • org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversal#addOutE(String, String, Object…​)

    • org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversal#addInV(String, String, Object…​)

    • org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversal#selectV3d2()

    • org.apache.tinkerpop.gremlin.process.traversal.Bindings()

    • org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversalSource#withBindings(Bindings)

    • org.apache.tinkerpop.gremlin.structure.Transaction.submit(Function)

    • org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversal#sack(BiFunction,String)

    • org.apache.tinkerpop.gremlin.process.traversal.strategy.finalization.LazyBarrierStrategy

    • org.apache.tinkerpop.gremlin.process.traversal.TraversalSideEffects (various methods)

    • org.apache.tinkerpop.gremlin.process.computer.traversal.step.VertexComputing#generateComputer(Graph)

    • org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversal#groupV3d0(String)

    • org.apache.tinkerpop.gremlin.process.traversal.dsl.graph.GraphTraversal#groupV3d0()

    • org.apache.tinkerpop.gremlin.structure.Graph.Features.VertexPropertyFeatures#supportsAddProperty()

    • org.apache.tinkerpop.gremlin.structure.Graph.Features.VertexPropertyFeatures#FEATURE_ADD_PROPERTY

    • org.apache.tinkerpop.gremlin.structure.Graph.OptIn#SUITE_GROOVY_PROCESS_STANDARD

    • org.apache.tinkerpop.gremlin.structure.Graph.OptIn#SUITE_GROOVY_PROCESS_COMPUTER

    • org.apache.tinkerpop.gremlin.structure.Graph.OptIn#SUITE_GROOVY_ENVIRONMENT

    • org.apache.tinkerpop.gremlin.structure.Graph.OptIn#SUITE_GROOVY_ENVIRONMENT_INTEGRATE

    • org.apache.tinkerpop.gremlin.structure.io.Io.Builder#registry(IoRegistry)

    • org.apache.tinkerpop.gremlin.structure.io.graphson.GraphSONMapper.Builder#embedTypes(boolean)

    • org.apache.tinkerpop.gremlin.structure.Transaction.submit(Function)

    • org.apache.tinkerpop.gremlin.structure.util.detached.DetachedEdge(Object,String,Map,Pair,Pair)

    • org.apache.tinkerpop.gremlin.util.CoreImports

    • org.apache.tinkerpop.gremlin.util.ScriptEngineCache

    • org.apache.tinkerpop.gremlin.process.computer.util.ConfigurationTraversal

  • gremlin-driver

    • org.apache.tinkerpop.gremlin.driver.Cluster$Builder#reconnectIntialDelay(int)

    • org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV1d0(GryoMapper)

    • org.apache.tinkerpop.gremlin.driver.ser.AbstractGraphSONMessageSerializerV2d0#TOKEN_USE_MAPPER_FROM_GRAPH

    • org.apache.tinkerpop.gremlin.driver.ser.AbstractGryoSONMessageSerializerV2d0#TOKEN_USE_MAPPER_FROM_GRAPH

  • gremlin-groovy

    • org.apache.tinkerpop.gremlin.groovy.AbstractImportCustomizerProvider

    • org.apache.tinkerpop.gremlin.groovy.CompilerCustomizerProvider

    • org.apache.tinkerpop.gremlin.groovy.DefaultImportCustomizerProvider

    • org.apache.tinkerpop.gremlin.groovy.EmptyImportCustomizerProvider

    • org.apache.tinkerpop.gremlin.groovy.ImportCustomizerProvider

    • org.apache.tinkerpop.gremlin.groovy.NoImportCustomizerProvider

    • org.apache.tinkerpop.gremlin.groovy.engine.ConcurrentBindings

    • org.apache.tinkerpop.gremlin.groovy.engine.GremlinExecutor#build(String,List,List,List,Map)

    • org.apache.tinkerpop.gremlin.groovy.engine.GremlinExecutor#getScriptEngines()

    • org.apache.tinkerpop.gremlin.groovy.engine.GremlinExecutor#getGlobalBindings()

    • org.apache.tinkerpop.gremlin.groovy.engine.GremlinExecutor.Builder#enabledPlugins(Set)

    • org.apache.tinkerpop.gremlin.groovy.engine.GremlinExecutor.Builder#addEngineSettings(String,List,List,List,Map)

    • org.apache.tinkerpop.gremlin.groovy.engine.GremlinExecutor.Builder#engineSettings(Map)

    • org.apache.tinkerpop.gremlin.groovy.engine.GremlinExecutor.Builder#use(List)

    • org.apache.tinkerpop.gremlin.groovy.engine.ScriptEngines

    • org.apache.tinkerpop.gremlin.groovy.function.*

    • org.apache.tinkerpop.gremlin.groovy.plugin.*

    • org.apache.tinkerpop.gremlin.groovy.plugin.credential.*

    • org.apache.tinkerpop.gremlin.groovy.jsr223.DependencyManager

    • org.apache.tinkerpop.gremlin.groovy.jsr223.GremlinGroovyScriptEngine(ImportCustomizerProvider)

    • org.apache.tinkerpop.gremlin.groovy.jsr223.GremlinGroovyScriptEngine(CompilerCustomizerProvider)

    • org.apache.tinkerpop.gremlin.groovy.jsr223.GremlinGroovyScriptEngine#plugins()

    • org.apache.tinkerpop.gremlin.groovy.jsr223.ScriptExecutor

    • org.apache.tinkerpop.gremlin.groovy.jsr223.ScriptEnginePluginAcceptor

    • org.apache.tinkerpop.gremlin.groovy.jsr223.customizer.SandboxExtension

    • org.apache.tinkerpop.gremlin.groovy.jsr223.customizer.*

    • org.apache.tinkerpop.gremlin.groovy.util.DependencyGrabber#deleteDependenciesFromPath(org.apache.tinkerpop.gremlin.groovy.plugin.Artifact)

    • org.apache.tinkerpop.gremlin.groovy.util.DependencyGrabber#copyDependenciesToPath(org.apache.tinkerpop.gremlin.groovy.plugin.Artifact)

  • gremlin-python

    • org.apache.tinkerpop.gremlin.python.jsr223.GremlinJythonScriptEngine#()

  • gremlin-server

    • org.apache.tinkerpop.gremlin.server.GremlinServer(ServerGremlinExecutor)

    • org.apache.tinkerpop.gremlin.server.Settings#plugins

    • org.apache.tinkerpop.gremlin.server.auth.AllowAllAuthenticator.newSaslNegotiator()

    • org.apache.tinkerpop.gremlin.server.auth.Authenticator.newSaslNegotiator()

    • org.apache.tinkerpop.gremlin.server.auth.Krb5Authenticator.newSaslNegotiator()

    • org.apache.tinkerpop.gremlin.server.auth.SimpleAuthenticator.newSaslNegotiator()

    • org.apache.tinkerpop.gremlin.server.handler.IteratorHandler

    • org.apache.tinkerpop.gremlin.server.handler.NioGremlinResponseEncoder

    • org.apache.tinkerpop.gremlin.server.handler.WsGremlinResponseEncoder

    • org.apache.tinkerpop.gremlin.server.handler.OpSelectorHandler.errorMeter

    • org.apache.tinkerpop.gremlin.server.op.control.*

    • org.apache.tinkerpop.gremlin.server.op.AbstractEvalOpProcessor.errorMeter

    • org.apache.tinkerpop.gremlin.server.op.AbstractEvalOpProcessor.validBindingName

    • org.apache.tinkerpop.gremlin.server.op.session.Session.kill()

    • org.apache.tinkerpop.gremlin.server.op.session.Session.manualkill()

  • hadoop-gremlin

    • org.apache.tinkerpop.gremlin.hadoop.Constants#GREMLIN_HADOOP_GRAPH_INPUT_FORMAT

    • org.apache.tinkerpop.gremlin.hadoop.Constants#GREMLIN_HADOOP_GRAPH_OUTPUT_FORMAT

    • org.apache.tinkerpop.gremlin.hadoop.Constants#GREMLIN_HADOOP_GRAPH_INPUT_FORMAT_HAS_EDGES

    • org.apache.tinkerpop.gremlin.hadoop.Constants#GREMLIN_HADOOP_GRAPH_OUTPUT_FORMAT_HAS_EDGES

    • org.apache.tinkerpop.gremlin.hadoop.Constants#GREMLIN_SPARK_GRAPH_INPUT_RDD

    • org.apache.tinkerpop.gremlin.hadoop.Constants#GREMLIN_SPARK_GRAPH_OUTPUT_RDD

  • spark-gremlin

    • org.apache.tinkerpop.gremlin.spark.groovy.plugin.SparkGremlinPlugin

  • tinkergraph-gremlin

    • org.apache.tinkerpop.gremlin.tinkergraph.groovy.plugin.TinkerGraphGremlinPlugin

    • org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerGraph#CONFIG_*

    • org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerIoRegistry

    • org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerIoRegistryV1d0#getInstance()

    • org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerIoRegistryV2d0#getInstance()

Please see the javadoc deprecation notes or upgrade documentation specific to when the deprecation took place to understand how to resolve this breaking change.

Gremlin-server.sh and Init Scripts

gremlin-server.sh is now also an init script and can no longer be started without parameters. To start it in the foreground with defaults like previous usage, please use the console parameter. Also, gremlin-server.sh will continue to start in the foreground when provided a yaml configuration file.

How to install as a service has been added to the Reference Documentation - As A Service.

The switch name has changed for installing dependencies. -i has been deprecated and replaced by install.

Removal of useMapperFromGraph

The userMapperFromGraph serialization configuration option was used to allow the IO configurations of a specific graph to be assigned to a specific serializer. This feature has been removed completely now. Please use the ioRegistries configuration option to add one or more specific Graph serialization capabilities to a serializer.

serializers:
  - { className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV1d0, config: { ioRegistries: [org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerIoRegistryV1d0] }}            # application/vnd.gremlin-v1.0+gryo

Gremlin-server.bat

The switch name has changed for installing dependencies. -i has been deprecated and replaced by install.

SparkGraphComputer GryoRegistrator

Historically, SparkGraphComputer has used GryoSerializer to handle the serialization of objects in Spark. The reason this exists is because TinkerPop uses a shaded version of Kryo and thus, couldn’t use the standard KryoSerializer-model provided by Spark. However, a "shim model" was created which allows for the shaded and unshaded versions of Kryo to interact with one another. To this end, KryoSerializer can now be used with a GryoRegistrator. The properties file for a SparkGraphComputer now looks as follows:

spark.serializer=org.apache.spark.serializer.KryoSerializer
spark.kryo.registrator=org.apache.tinkerpop.gremlin.spark.structure.io.gryo.GryoRegistrator

If the old GryoSerializer model is desired, then the properties file should simply look as before:

spark.serializer=org.apache.tinkerpop.gremlin.spark.structure.io.gryo.GryoSerializer

ScriptInputFormat

The API for the script provided to a ScriptInputFormat has changed slightly. The signature for parse(line, factory) is now simply parse(line). The inclusion of factory was deprecated in 3.1.2. Instead of using the {{factory}} to get the {{StarGraph}} there is a {{graph}} variable in the glocal context of the script. Simply use that directly in the script.

Upgrading for Providers

Important
It is recommended that providers also review all the upgrade instructions specified for users. Many of the changes there may prove important for the provider’s implementation.

Graph System Providers

GremlinPlugin

The previously deprecated GremlinPlugin system has been removed. The old GremlinPlugin interface formerly resided in the org.apache.tinkerpop.gremlin.groovy.plugin package of gremlin-groovy. This interface was replaced by an interface of the same name in 3.2.4, which now resides in the org.apache.tinkerpop.gremlin.jsr223 package in gremlin-core. Obviously, existing plugins will need to be updated to use this new interface.

The plugin model has changed slightly to be more generic and not specifically bound to Groovy based script engines. Under the new model, the plugin simply returns Customizer instances that can be applied generically to any ScriptEngine or specifically to a particular ScriptEngine. More details can be found in the Provider Documentation

Graph Database Providers

Test Suite Removal

A number of test suites that were previously deprecated have been removed which should reduce the burden on graph providers who are implementing TinkerPop. Test suites related to perfrmance based on junit-benchmarks have been removed as have the suites in gremlin-groovy-test (in fact, this entire module has been removed). Specifically, providers should be concerned with breaking changes related to the removal of:

  • StructurePerformanceSuite

  • ProcessPerformanceSuite

  • GroovyEnvironmentPerformanceSuite

  • GroovyProcessStandardSuite

  • GroovyProcessComputerSuite

  • GroovyEnvironmentSuite

  • GroovyEnvironmentIntegrateSuite

Those graph providers who relied on these tests should simply remove them from their respective test suites. Beware of OptOut annotations that reference tests in these suites as test failure will occur if those references are not removed.

TransactionException

The AbstractTransaction.TransactionException class is now just TransactionException which extends RuntimeExcetpion rather than Exception. Providers should consider using this exception to wrap their own on calls to Transaction.commit() or Transaction.rollback(). By throwing this exception, the TinkerPop stack can better respond to transaction problems and it allows for more common, generalized error handling for users.

Driver Providers

SASL Byte Array

Gremlin Server no longer supports accepting a byte array for the value passed to the "sasl" parameter in authentication messages. It only accepts a Base64 encoded string.

TinkerPop 3.2.0

nine inch gremlins

Nine Inch Gremlins

TinkerPop 3.2.11

Release Date: January 2, 2019

Please see the changelog for a complete list of all the modifications that are part of this release.

TinkerPop 3.2.10

Release Date: October 15, 2018

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

SASL in Gremlin.Net

The Gremlin Javascript Driver now supports SASL Plain Text authentication against a Gremlin Server.

SSL Security

TinkerPop improves its security posture by removing insecure defaults and adding forward-looking standards support.

Gremlin Server no longer supports automatically creating self-signed certificates. Self-signed certificates can still be created manually outside of Gremlin Server. If ssl is enabled, a key store must be configured.

Cluster client no longer trusts all certs by default as this is an insecure configuration. Instead, if no trust store is configured, Cluster will use the default CA certs. To revert to the previous behavior and accept all certs, it must be explicitly configured.

This release introduces JKS and PKCS12 support. JKS is the legacy Java Key Store. PKCS12 has better cross-platform support and is gaining in adoption. Be aware that JKS is the default on Java 8. Java 9 and higher use PKCS12 as the default. Both Java keytool and OpenSSL tools can create, read, update PKCS12 files.

Other new features include specifying SSL protocols and cipher suites. The packaged *-secure.yaml files now restrict the protocol to TLSv1.2 by default.

PEM-based configurations are deprecated and may be removed in a future release.

Bulk Import and Export

TinkerPop has provided some general methods for importing and exporting data, but more and more graph providers are producing their own bulk import/export facilities and they are more efficient and easier to use than TinkerPop’s methods. As a result, TinkerPop will now refer users to the bulk import/export features of individual graph providers and as such, has deprecated BulkLoaderVertexProgram as of this release.

As part of this change, the BulkDumperVertexProgram has been renamed to CloneVertexProgram with the former being deprecated. CloneVertexProgram is more aptly named, as it essentially copies a graph from a graph InputFormat to a graph OutputFormat.

Docker Images

Docker images are now available on Docker Hub for Gremlin Console and Gremlin Server.

$ docker run -it tinkerpop/gremlin-console:3.5.0-SNAPSHOT
$ docker run tinkerpop/gremlin-server:3.5.0-SNAPSHOT

TimedInterruptCustomizerProvider

In Gremlin Server, it is best not to use 'TimedInterruptCustomizerProvider' because it can compete with the 'scriptEvaluationTimeout' setting and produce a different error path. Simply rely on 'scriptEvaluationTimeout' as it covers both script evaluation time and result iteration time.

TinkerFactory.createGratefulDead()

The Grateful Dead dataset has been with TinkerPop since the early days of 1.x. It has always been available as a packaged dataset that needed to be loaded through the various IO options available, while other toy graphs had the benefit of TinkerFactory to help get them bootstrapped. For 3.2.10, Grateful Dead is now more conveniently loaded via that same method as the other toy graphs with TinkerFactory.createGratefulDead().

Gremlin Javascript Script Submission

Gremlin Javascript can now submit script, with optional bindings, using the Client class:

const gremlin = require('gremlin');
const client = new gremlin.driver.Client('ws://localhost:8182/gremlin', { traversalSource: 'g' });

client.submit('g.V().tail()')
    .then(result => {
        console.log(result.length);
        console.log(result.toArray()[0]);
    });

client.submit('g.V(vid)', { vid: 1 })
    .then(result => {
        console.log(result.length);
        // Get the first item
        console.log(result.first());
    });

and also allows translation of bytecode steps into script:

const gremlin = require('gremlin');
const graph = new gremlin.process.Graph();
const client = new gremlin.driver.Client('ws://localhost:8182/gremlin', { traversalSource: 'g' });
const translator = new gremlin.process.Translator('g');

const g = graph.traversal();
const script = translator.translate(g.V().tail().getBytecode());

client.submit(script)
    .then(result => {
        console.log(result.length);
        console.log(result.first());
    });

Upgrading for Providers

Graph Database Providers

Bulk Import and Export

As noted in the user section, TinkerPop has deprecated its bulk loading feature in BulkLoaderVertexProgram and will refer TinkerPop users who need bulk import/export capabilities to the native tools of the graph database they have chosen. If a graph database provider does not have any bulk loading tools it can choose to build graph InputFormat and OutputFormat implementations which can be used by CloneVertexProgram (formerly BulkDumperVertexProgram) as a easy way to get such a feature.

TinkerPop 3.2.9

Release Date: May 8, 2018

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

Lambda Construction

It was realized quite shortly after release of 3.2.8 that there was a bug in construction of Lambda instances:

gremlin> org.apache.tinkerpop.gremlin.util.function.Lambda.function("{ it.get() }")
(class: org/apache/tinkerpop/gremlin/util/function/Lambda$function, method: callStatic signature: (Ljava/lang/Class;[Ljava/lang/Object;)Ljava/lang/Object;) Illegal type in constant pool
Type ':help' or ':h' for help.
Display stack trace? [yN]n

The problem was related to a bug in Groovy 2.4.14 and was fixed in 2.4.15.

TinkerPop 3.2.8

Release Date: April 2, 2018

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

Improved Connection Monitoring

Gremlin Server now has two new settings: idleConnectionTimeout and keepAliveInterval. The keepAliveInterval tells Gremlin Server how long it should wait between writes to a client before it issues a "ping" to that client to see if it is still present. The idleConnectionTimeout represents how long Gremlin Server should wait between requests from a client before it closes the connection on the server side. By default, these two configurations are set to zero, meaning that they are both disabled.

This change should help to alleviate issues where connections are left open on the server longer than they should be by clients that might mysteriously disappear without properly closing their connections.

Gremlin.Net Lambdas

Gremlin.Net now has a Lambda class that can be used to construct Groovy or Java lambdas which will be evaluated on the server.

Gremlin.Net Tokens Improved

The various Gremlin tokens (e.g. T, Order, Operator, etc.) that were implemented as Enums before in Gremlin.Net are now implemented as classes. This mainly allows them to implement interfaces which their Java counterparts already did. T for example now implements the new interface IFunction which simply mirrors its Java counterpart Function. Steps that expect objects for those interfaces as arguments now explicitly use the interface. Before, they used just object as the type for these arguments which made it hard for users to know what kind of object they can use. However, usage of these tokens themselves shouldn’t change at all (e.g. T.Id is still T.Id).

Gremlin.Net: Traversal Predicate Classes Merged

Gremlin.Net used two classes for traversal predicates: P and TraversalPredicate. Steps that worked with traversal predicates expected objects of type TraversalPredicate, but they were constructed from the P class (e.g. P.Gt(1) returned a TraversalPredicate). Merging these two classes into the P class should avoid unnecessary confusion. Most users should not notice this change as predicates can still be constructed exactly as before, e.g., P.Gt(1).And(P.Lt(3)) still works without any modifications. Only users that implemented their own predicates and used TraversalPredicate as the base class need to change their implementation to now use P as the new base class.

Upgrading for Providers

Graph System Providers

Kitchen Sink Test Graph

The "Kitchen Sink" test graph has been added to the gremlin-test module. It contains (or will contain) various disconnected subgraphs of that offer unique structures (e.g. a self-loop) for specific test cases. Graph systems that use the test suite should not have to make any changes to account for this new graph unless that system performs some form or special pre-initialization of their system in preparation for loading (e.g. requires a schema) or does the loading of the graph test data outside of the standard method in which TinkerPop provides.

TinkerPop 3.2.7

Release Date: December 17, 2017

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

Gremlin-Python Core Types

With the addition of UUID, Date, and Timestamp, Gremlin-Python now implements serializers for all core GraphSON types. Users that were using other types to represent this data can now use the Python classes datetime.datetime and`uuid.UUID` in GLV traversals. Since Python does not support a native Timestamp object, Gremlin-Python now offers a dummy class Timestamp, which allows users to wrap a float and submit it to the Gremlin Server as a Timestamp GraphSON type. Timestamp can be found in gremlin_python.statics.

EventStrategy Detachment

EventStrategy forced detachment of mutated elements prior to raising them in events. While this was a desired outcome, it may not have always fit every use case. For example, a user may have wanted a reference element or the actual element itself. As a result, EventStrategy has changed to allow it to be constructed with a detach() option, where it is possible to specify any of the following: null for no detachment, DetachedFactory for the original behavior, and ReferenceFactory for detachment that returns reference elements.

Embedded Remote Connection

As Gremlin Language Variants (GLVs) expand their usage and use of withRemote() becomes more common, the need to mock the "remote" in unit tests increases. To simplify mocking in Java, the new EmbeddedRemoteConnection provides a simple way to provide a "remote" that is actually local to the same JVM.

DSL Type Specification

Prior to this version, the Java annotation processor for Gremlin DSLs has tried to infer the appropriate type specifications when generating anonymous methods. It largely performed this inference on simple conventions in the DSL method’s template specification and there were times where it would fail. For example, a method like this:

public default GraphTraversal<S, E> person() {
    return hasLabel("person");
}

would generate an anonymous method like:

public static <S> SocialGraphTraversal<S, E> person() {
    return hasLabel("person");
}

and, of course, generate a compile error and E was not recognized as a symbol. The preferred generation would likely be:

public static <S> SocialGraphTraversal<S, S> person() {
    return hasLabel("person");
}

To remedy this situation, a new annotation has been added which allows the user to control the type specifications more directly providing a way to avoid/override the inference system:

@GremlinDsl.AnonymousMethod(returnTypeParameters = {"A", "A"}, methodTypeParameters = {"A"})
public default GraphTraversal<S, E> person() {
    return hasLabel("person");
}

which will then generate:

public static <A> SocialGraphTraversal<A, A> person() {
    return hasLabel("person");
}

Specify a Cluster Object

The :remote connect command can now take a pre-defined Cluster object as its argument as opposed to a YAML configuration file.

gremlin> cluster = Cluster.open()
==>localhost/127.0.0.1:8182
gremlin> :remote connect tinkerpop.server cluster
==>Configured localhost/127.0.0.1:8182

Remote Traversal Timeout

There was limited support for "timeouts" with remote traversals (i.e. those traversals executed using the withRemote() option) prior to 3.2.7. Remote traversals will now interrupt on the server using the scriptEvaluationTimeout setting in the same way that normal script evaluations would. As a reminder, interruptions for traversals are always considered "attempts to interrupt" and may not always succeed (a graph database implementation might not respect the interruption, for example).

Modifications to match()

The match()-step has been generalized to support the local scoping of all barrier steps, not just reducing barrier steps. Previously, the order().limit() clause would have worked globally yielding:

gremlin> g.V().match(
......1>   __.as('a').outE('created').order().by('weight',decr).limit(1).inV().as('b'),
......2>   __.as('b').has('lang','java')
......3> ).select('a','b').by('name')
==>[a:marko,b:lop]

However, now, order() (and all other barriers) are treated as local computations to the pattern and thus, the result set is:

gremlin> g.V().match(
......1>   __.as('a').outE('created').order().by('weight',decr).limit(1).inV().as('b'),
......2>   __.as('b').has('lang','java')
......3> ).select('a','b').by('name')
==>[a:marko,b:lop]
==>[a:josh,b:ripple]
==>[a:peter,b:lop]

Note that this is not that intense of a breaking change as all of the reducing barriers behaved in this manner previously. This includes steps like count(), min(), max(), sum(), group(), groupCount(), etc. This update has now generalized this behavior to all barriers and thus, adds aggregate(), dedup(), range(), limit(), tail(), and order() to the list of locally computed clauses.

Clone a Graph

In gremlin-test there is a new GraphHelper class that has a cloneElements() method. It will clone elements from the first graph to the second - GraphHelper.cloneElements(Graph original, Graph clone). This helper method is primarily intended for use in tests.

MutationListener Changes

The MutationListener has a method called vertexPropertyChanged which gathered callbacks when a property on a vertex was modified. The method had an incorrect signature though using Property instead of VertexProperty. The old method that used Property has now been deprecated and a new method added that uses VertexProperty. This new method has a default implementation that calls the old method, so this change should not cause breaks in compilation on upgrade. Internally, TinkerPop no longer calls the old method except by way of that proxy. Users who have MutationListener implementations can simply add the new method and override its behavior. The old method can thus be ignored completely.

Upgrading for Providers

Direction.BOTH Requires Duplication of Self-Edges

Prior to this release, there was no semantic check to determine whether a self-edge (e.g. e[1][2-self→2]) would be returned twice on a BOTH. The semantics have been specified now in the test suite where the edge should be returned twice as it is both an incoming edge and an outgoing edge.

TinkerPop 3.2.6

Release Date: August 21, 2017

Upgrading for Users

Please see the changelog for a complete list of all the modifications that are part of this release.

Deprecated useMapperFromGraph

The userMapperFromGraph configuration option for the Gremlin Server serializers has been deprecated. Change configuration files to use the ioRegistries option instead. The ioRegistries option is not a new feature, but it has not been promoted as the primary way to add IoRegistry instances to serializers.

WsAndHttpChannelizer

The WsAndHttpChannelizer has been added to allow for processing both WebSocket and HTTP requests on the same port and gremlin server. The SaslAndHttpBasicAuthenticationHandler has also been added to service authentication for both protocols in conjunction with the SimpleAuthenticator.

Upgrading for Providers

ReferenceVertex Label

ReferenceVertex.label() was hard coded to return EMPTY_STRING. At some point, ReferenceElements were suppose to return labels and ReferenceVertex was never updated as such. Note that ReferenceEdge and ReferenceVertexProperty work as expected. However, given a general change at ReferenceElement, the Gryo serialization of ReferenceXXX is different. If the vertex does not have a label Vertex.DEFAULT_LABEL is assumed.

TinkerPop 3.2.5

Release Date: June 12, 2017

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

DSL Support

It has always been possible to construct Domain Specific Languages (DSLs) with Gremlin, but the approach has required a somewhat deep understanding of the TinkerPop code base and it is not something that has had a recommended method for implementation. With this release, TinkerPop simplifies DSL development and provides the best practices for their implementation.

// standard Gremlin
g.V().hasLabel('person').
  where(outE("created").count().is(P.gte(2))).count()

// the same traversal as above written as a DSL
social.persons().where(createdAtLeast(2)).count()

GraphSON Path Serialization

Serialization of Path with GraphSON was inconsistent with Gryo in that all the properties on any elements of the Path were being included. With Gryo that, correctly, was not happening as that could be extraordinarily expensive. GraphSON serialization has now been modified to properly not include properties. That change can cause breaks in application code if that application code tries to access properties on elements in a Path as they will no longer be there. Applications that require the properties will need to alter their Gremlin to better restrict the data they want to retrieve.

Authentication Configuration

The server settings previously used authentication.className to set an authenticator for the the two provided authentication handler and channelizer classes to use. This has been deprecated in favor of authentication.authenticator. A class that extends AbstractAuthenticationHandler may also now be provided as authentication.authenticationHandler to be used in either of the provided channelizer classes to handle the provided authenticator

Default Maximum Parameters

It was learned that compilation for scripts with large numbers of parameters is more expensive than those with less parameters. It therefore becomes possible to make some mistakes with how Gremlin Server is used. A new setting on the StandardOpProcessor and SessionOpProcessor called maxParameters controls the number of parameters that can be passed in on a request. This setting is defaulted to sixteen.

Users upgrading to this version may notice errors in their applications if they use more than sixteen parameters. To fix this problem simply reconfigure Gremlin Server with a configuration as follows:

processors:
  - { className: org.apache.tinkerpop.gremlin.server.op.session.SessionOpProcessor, config: { maxParameters: 64 }}
  - { className: org.apache.tinkerpop.gremlin.server.op.standard.StandardOpProcessor, config: { maxParameters: 64 }}

The above configuration allows sixty-four parameters to be passed on each request.

GremlinScriptEngine Metrics

The GremlinScriptEngine has a number of new metrics about its cache size and script compilation times which should be helpful in understanding usage problems. As GremlinScriptEngine instances are used in Gremlin Server these metrics are naturally exposed as part of the standard metrics set. Note that metrics are captured for both sessionless requests as well as for each individual session that is opened.

Additional Error Information

Additional information on error responses from Gremlin Server should help make debugging errors easier. Error responses now have both the exception hierarchy and the stack trace that was generated on the server. In this way, receiving an error on a client doesn’t mean having to rifle through Gremlin Server logs to try to find the associated error.

This change has been applied to all Gremlin Server protocols. For the binary protocol and the Java driver this change means that the ResponseException thrown from calls to submit() requests to the server now have the following methods:

public Optional<String> getRemoteStackTrace()

public Optional<List<String>> getRemoteExceptionHierarchy()

The HTTP protocol has also been updated and returns both exceptions and stackTrace fields in the response:

{
        "message": "Division by zero",
        "Exception-Class": "java.lang.ArithmeticException",
        "exceptions": ["java.lang.ArithmeticException"],
        "stackTrace": "java.lang.ArithmeticException: Division by zero\n\tat java.math.BigDecimal.divide(BigDecimal.java:1742)\n\tat org.codehaus.groovy.runtime.typehandling.BigDecimalMath.divideImpl(BigDecimalMath.java:68)\n\tat org.codehaus.groovy.runtime.typehandling.IntegerMath.divideImpl(IntegerMath.java:49)\n\tat org.codehaus.groovy.runtime.dgmimpl.NumberNumberDiv$NumberNumber.invoke(NumberNumberDiv.java:323)\n\tat org.codehaus.groovy.runtime.callsite.PojoMetaMethodSite.call(PojoMetaMethodSite.java:56)\n\tat org.codehaus.groovy.runtime.callsite.CallSiteArray.defaultCall(CallSiteArray.java:48)\n\tat org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:113)\n\tat org.codehaus.groovy.runtime.callsite.AbstractCallSite.call(AbstractCallSite.java:125)\n\tat Script4.run(Script4.groovy:1)\n\tat org.apache.tinkerpop.gremlin.groovy.jsr223.GremlinGroovyScriptEngine.eval(GremlinGroovyScriptEngine.java:834)\n\tat org.apache.tinkerpop.gremlin.groovy.jsr223.GremlinGroovyScriptEngine.eval(GremlinGroovyScriptEngine.java:547)\n\tat javax.script.AbstractScriptEngine.eval(AbstractScriptEngine.java:233)\n\tat org.apache.tinkerpop.gremlin.groovy.engine.ScriptEngines.eval(ScriptEngines.java:120)\n\tat org.apache.tinkerpop.gremlin.groovy.engine.GremlinExecutor.lambda$eval$2(GremlinExecutor.java:314)\n\tat java.util.concurrent.FutureTask.run(FutureTask.java:266)\n\tat java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)\n\tat java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)\n\tat java.lang.Thread.run(Thread.java:745)\n"
}

Note that the Exception-Class which was added in a previous version has been deprecated and replaced by these new fields.

Gremlin Console Scripting

The gremlin.sh command has two flags, -i and -e, which are used to pass a script and arguments into the Gremlin Console for execution. Those flags now allow for passing multiple scripts and related arguments to be supplied which can yield greater flexibility in automation tasks.

$ bin/gremlin.sh -i y.groovy 1 2 3 -i x.groovy
$ bin/gremlin.sh -e y.groovy 1 2 3 -e x.groovy

Path support for by()-, from()-, to()-modulation

It is now possible to extract analyze sub-paths using from() and to() modulations with respective, path-based steps. Likewise, simplePath() and cyclicPath() now support, along with from() and to(), by()-modulation so the cyclicity is determined by projections of the path data. This extension is fully backwards compatible.

GraphManager versus DefaultGraphManager

Gremlin Server previously implemented its own final GraphManager class. Now, the GraphManager has been changed to an interface, and users can supply their own GraphManager implementations in their YAML. The previous GraphManager class was meant be used by classes internal to Gremlin Server, but it was public so if it was used for some reason by users then then a compile error can be expected. To correct this problem, which will likely manifest as a compile error when trying to create a new GraphManager() instance, simply change the code to new DefaultGraphManager(Settings).

In addition to the change mentioned above, several methods on GraphManager were deprecated:

  • getGraphs() should be replaced by the combination of getGraphNames() and then getGraph(String)

  • getTraversalSources() is similarly replaced and should instead use a combination of getTraversalSourceNames() and getTraversalSource(String)

Gremlin-Python Driver

Gremlin-Python now offers a more complete driver implementation that uses connection pooling and the Python concurrent.futures module to provide asynchronous I/0 using threading. The default underlying WebSocket client implementation is still provided by Tornado, but it is trivial to plug in another client by defining the Transport interface.

Using the DriverRemoteConnection class is the exact same as in previous versions; however, DriverRemoteConnection now uses the new Client class to submit messages to the server.

The Client class implementation/interface is based on the Java Driver, with some restrictions. Most notably, Gremlin-Python does not yet implement the Cluster class. Instead, Client is instantiated directly. Usage is as follows:

from gremlin_python.driver import client

client = client.Client('ws://localhost:8182/gremlin', 'g')
result_set = client.submit('1 + 1')
future_results = result_set.all()  # returns a concurrent.futures.Future
results = future_results.result()  # returns a list
assert results == [2]
client.close()  # don't forget to close underlying connections

Upgrading for Providers

Important
It is recommended that providers also review all the upgrade instructions specified for users. Many of the changes there may prove important for the provider’s implementation.

Graph Database Providers

SimplePathStep and CyclicPathStep now PathFilterStep

The Gremlin traversal machine use to support two step instructions: SimplePathStep and CyclicPathStep. These have been replaced by a high-level instruction called PathFilterStep which is boolean configured for simple or cyclic paths. Furthermore, PathFilterStep also support from()-, to()-, and by()-modulation.

LazyBarrierStrategy No Longer End Appends Barriers

LazyBarrierStrategy was trying to do to much by considering Traverser effects on network I/O by appending an NoOpBarrierStrategy to the end of the root traversal. This should not be accomplished by LazyBarrierStrategy, but instead by RemoteStrategy. RemoteStrategy now tries to barrier-append. This may effect the reasoning logic in some ProviderStrategies. Most likely not, but just be aware.

TinkerPop 3.2.4

Release Date: February 8, 2017

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

TinkerGraph Deserialization

A TinkerGraph deserialized from Gryo or GraphSON is now configured with multi-properties enabled. This change allows TinkerGraphs returned from Gremlin Server to properly return multi-properties, which was a problem seen when subgraphing a graph that contained properties with a setting other than Cardinality.single.

This change could be considered breaking in the odd chance that a TinkerGraph returned from Gremlin Server was later mutated, because calls to property(k,v) would default to Cardinality.list instead of Cardinality.single. In the event that this is a problem, simple change calls to property(k,v) to property(Cardinality.single,k,v) and explicitly set the Cardinality.

Traversal Promises

The Traversal API now has a new promise() method. These methods return a promise in the form of a CompleteableFuture. Usage is as follows:

gremlin> promise = g.V().out().promise{it.next()}
==>java.util.concurrent.CompletableFuture@4aa3d36[Completed normally]
gremlin> promise.join()
==>v[3]
gremlin> promise.isDone()
==>true
gremlin> g.V().out().promise{it.toList()}.thenApply{it.size()}.get()
==>6

At this time, this method is only used for traversals that are configured using withRemote().

If/Then-Semantics with Choose Step

Gremlin’s choose()-step supports if/then/else-semantics. Thus, to effect if/then-semantics, identity() was required. Thus, the following two traversals below are equivalent with the later being possible in this release.

g.V().choose(hasLabel('person'),out('created'),identity())
g.V().choose(hasLabel('person'),out('created'))

FastNoSuchElementException converted to regular NoSuchElementException

Previously, a call to Traversal.next() that did not have a result would throw a FastNoSuchElementException. This has been changed to a regular NoSuchElementException that includes the stack trace. Code that explicitly catches FastNoSuchElementException should be converted to check for the more general class of NoSuchElementException.

ScriptEngine support in gremlin-core

ScriptEngine and GremlinPlugin infrastructure has been moved from gremlin-groovy to gremlin-core to allow for better re-use across different Gremlin Language Variants. At this point, this change is non-breaking as it was implemented through deprecation.

The basic concept of a ScriptEngine has been replaced by the notion of a GremlinScriptEngine (i.e. a "ScriptEngine" that is specifically tuned for executing Gremlin-related scripts). "ScriptEngine" infrastructure has been developed to help support this new interface, specifically GremlinScriptEngineFactory and GremlinScriptEngineManager. Prefer use of this infrastructure when instantiating a GremlinScriptEngine rather than trying to instantiate directly.

For example, rather than instantiate a GremlinGroovyScriptEngine with the constructor:

GremlinScriptEngine engine = new GremlinGroovyScriptEngine();

prefer to instantiate it as follows:

GremlinScriptEngineManager manager = new CachedGremlinScriptEngineManager();
GremlinScriptEngine engine = manager.getEngineByName("gremlin-groovy");

Related to the addition of GremlinScriptEngine, org.apache.tinkerpop.gremlin.groovy.plugin.GremlinPlugin in gremlin-groovy has been deprecated and then replaced by org.apache.tinkerpop.gremlin.jsr223.GremlinPlugin. The new version of GremlinPlugin is similar but does carry some new methods to implement that involves the new Customizer interface. The Customizer interface is the way in which GremlinScriptEngine instance can be configured with imports, initialization scripts, compiler options, etc.

Note that a GremlinPlugin can be applied to a GremlinScriptEngine by adding it to the GremlinScriptEngineManager that creates it.

GremlinScriptEngineManager manager = new CachedGremlinScriptEngineManager();
manager.addPlugin(ImportGremlinPlugin.build().classImports(java.awt.Color.class).create());
GremlinScriptEngine engine = manager.getEngineByName("gremlin-groovy");

All of this new infrastructure is currently optional on the 3.2.x line of code. More detailed documentation will for these changes will be supplied as part of 3.3.0 when these features become mandatory and the deprecated code is removed.

SSL Client Authentication

Added new server configuration option ssl.needClientAuth.

Upgrading for Providers

Important
It is recommended that providers also review all the upgrade instructions specified for users. Many of the changes there may prove important for the provider’s implementation.

Graph Database Providers

CloseableIterator

Prior to TinkerPop 3.x, Blueprints had the notion of a CloseableIterable which exposed a way for Graph Providers to offer a way to release resources that might have been opened when returning vertices and edges. That interface was never exposed in TinkerPop 3.x, but has now been made available via the new CloseableIterator. Providers may choose to use this interface or not when returning values from Graph.vertices() and Graph.edges().

It will be up to users to know whether or not they need to call close(). Of course, users should typically not be operating with the Graph Structure API, so it’s unlikely that they would be calling these methods directly in the first place. It is more likely that users will be calling Traversal.close(). This method will essentially iterate the steps of the Traversal and simply call close() on any steps that implement AutoCloseable. By default, GraphStep now implements AutoCloseable which most Graph Providers will extend upon (as was done with TinkerGraph’s TinkerGraphStep), so the integration should largely come for free if the provider simply returns a CloseableIterator from Graph.vertices() and Graph.edges().

HasContainer AndP Splitting

Previously, GraphTraversal made it easy for providers to analyze P-predicates in HasContainers, but always splitting AndP predicates into their component parts. This helper behavior is no longer provided because, 1.) AndP can be inserted into a XXXStep in other ways, 2.) the providers XXXStep should process AndP regardless of GraphTraversal helper, and 3.) the GraphTraversal helper did not recursively split. A simple way to split AndP in any custom XXXStep that implements HasContainerHolder is to use the following method:

@Override
public void addHasContainer(final HasContainer hasContainer) {
  if (hasContainer.getPredicate() instanceof AndP) {
    for (final P<?> predicate : ((AndP<?>) hasContainer.getPredicate()).getPredicates()) {
      this.addHasContainer(new HasContainer(hasContainer.getKey(), predicate));
    }
  } else
    this.hasContainers.add(hasContainer);
}
Duplicate Multi-Properties

Added supportsDuplicateMultiProperties to VertexFeatures so that graph provider who only support unique values as multi-properties have more flexibility in describing their graph capabilities.

Deprecated OptIn

In 3.2.1, all junit-benchmark performance tests were deprecated. At that time, the OptIn representations of these tests should have been deprecated as well, but they were not. That omission has been remedied now. Specifically, the following fields were deprecated:

  • OptIn.SUITE_GROOVY_ENVIRONMENT_PERFORMANCE

  • OptIn.SUITE_PROCESS_PERFORMANCE

  • OptIn.SUITE_STRUCTURE_PERFORMANCE

As of 3.2.4, the following test suites were also deprecated:

  • OptIn.SUITE_GROOVY_PROCESS_STANDARD

  • OptIn.SUITE_GROOVY_PROCESS_COMPUTER

  • OptIn.SUITE_GROOVY_ENVIRONMENT

  • OptIn.SUITE_GROOVY_ENVIRONMENT_INTEGRATE

Future testing of gremlin-groovy (and language variants in general) will be handled differently and will not require a Graph Provider to validate its operations with it. Graph Providers may now choose to remove these tests from their test suites, which should reduce the testing burden.

Deprecated getInstance()

TinkerPop has generally preferred static instance() methods over getInstance(), but getInstance() was used in some cases nonetheless. As of this release, getInstance() methods have been deprecated in favor of instance(). Of specific note, custom IoRegistry (as related to IO in general) and Supplier<ClassResolver> (as related to Gryo serialization in general) now both prefer instance() over getInstance() given this deprecation.

Drivers Providers

Force Close

Closing a session will first attempt a proper close of any open transactions. A problem can occur, however, if there is a long run job (e.g. an OLAP-based traversal) executing, as that job will block the calls to close the transactions. By exercising the option to a do a "forced close" the session will skip trying to close the transactions and just attempt to interrupt the long run job. By not closing transactions, the session leaves it up to the underlying graph database to sort out how it will deal with those orphaned transactions. On the positive side though (for those graphs which do that well) , long run jobs have the opportunity to be cancelled without waiting for a timeout of the job itself which will allow resources to be released earlier.

The "force" argument is passed on the "close" message and is a boolean value. This is an optional argument to "close" and defaults to false.

SASL Authentication

Gremlin Supports SASL based authentication. The server accepts either a byte array or Base64 encoded String as the in the sasl argument on the RequestMessage, however it sends back a byte array only. Some serializers or serializer configurations don’t work well with that approach (specifically the "toString" configuration on the Gryo serializer) as the byte array is returned in the ResponseMessage result. In the case of the "toString" serializer the byte array gets "toString’d" and the can’t be read by the client.

In 3.2.4, the byte array is still returned in the ResponseMessage result, but is also returned in the status attributes under a sasl key as a Base64 encoded string. In this way, the client has options on how it chooses to process the authentication response and the change remains backward compatible. Drivers should upgrade to using the Base64 encoded string however as the old approach will likely be removed in the future.

TinkerPop 3.2.3

Release Date: October 17, 2016

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

Renamed Null Result Preference

In 3.2.2, the Gremlin Console introduced a setting called empty.result.indicator, which controlled the output that was presented when no result was returned. For consistency, this setting has been renamed to result.indicator.null and can be set as follows:

gremlin> graph = TinkerGraph.open()
==>tinkergraph[vertices:0 edges:0]
gremlin> graph.close()
==>null
gremlin> :set result.indicator.null nil
gremlin> graph = TinkerGraph.open()
==>tinkergraph[vertices:0 edges:0]
gremlin> graph.close()
==>nil
gremlin> :set result.indicator.null ""
gremlin> graph = TinkerGraph.open()
==>tinkergraph[vertices:0 edges:0]
gremlin> graph.close()
gremlin>

Java Driver Keep-Alive

The Java Driver now has a keepAliveInterval setting, which controls the amount of time in milliseconds it should wait on an inactive connection before it sends a message to the server to keep the connection maintained. This should help environments that use a load balancer in front of Gremlin Server by ensuring connections are actively maintained even during periods of inactivity.

Where Step Supports By-Modulation

It is now possible to use by() with where() predicate-based steps. Previously, without using match(), if you wanted to know who was older than their friend, the following traversal would be used.

gremlin> g.V().as('a').out('knows').as('b').
......1>   filter(select('a','b').by('age').where('a', lt('b')))
==>v[4]

Now, with where().by() support, the above traversal can be expressed more succinctly and more naturally as follows.

gremlin> g.V().as('a').out('knows').as('b').
......1>   where('a', lt('b')).by('age')
==>v[4]

Change In has() Method Signatures

The TinkerPop 3.2.2 release unintentionally introduced a breaking change for some has() method overloads. In particular the behavior for single item array arguments was changed:

gremlin> g.V().hasLabel(["software"] as String[]).count()
==>0

Prior this change single item arrays were treated like there was only that single item:

gremlin> g.V().hasLabel(["software"] as String[]).count()
==>2
gremlin> g.V().hasLabel("software").count()
==>2

TinkerPop 3.2.3 fixes this misbehavior and all has() method overloads behave like before, except that they no longer support no arguments.

Deprecated reconnectInitialDelay

The reconnectInitialDelay setting on the Cluster builder has been deprecated. It no longer serves any purpose. The value for the "initial delay" now comes from reconnectInterval (there are no longer two separate settings to control).

TraversalSource.close()

TraversalSource now implements AutoCloseable, which means that the close() method is now available. This new method is important in cases where withRemote() is used, as withRemote() can open "expensive" resources that need to be released.

In the case of TinkerPop’s DriverRemoteConnection, close() will destroy the Client instance that is created internally by withRemote() as shown below:

gremlin> graph = EmptyGraph.instance()
==>emptygraph[empty]
gremlin> g = graph.traversal().withRemote('conf/remote-graph.properties')
==>graphtraversalsource[emptygraph[empty], standard]
gremlin> g.close()
gremlin>

Note that the withRemote() method will call close() on a RemoteConnection passed directly to it as well, so there is no need to do that manually.

IO Reference Documentation

There is new reference documentation for the various IO formats. The documentation provides more details and samples that should be helpful to users and providers who intend to work directly with the TinkerPop supported serialization formats: GraphML, GraphSON and Gryo.

Upgrading for Providers

Important
It is recommended that providers also review all the upgrade instructions specified for users. Many of the changes there may prove important for the provider’s implementation.

Graph System Providers

Default LazyBarrierStrategy

LazyBarrierStrategy has been included as a default strategy. LazyBarrierStrategy walks a traversal and looks for "flatMaps" (out(), in(), both(), values(), V(), etc.) and adds "lazy barriers" to dam up the stream so to increase the probability of bulking the traversers. One of the side-effects is that:

g.V().out().V().has(a)

is compiled to:

g.V().out().barrier().V().barrier().has(a)

Given that LazyBarrierStrategy is an OptimizationStrategy, it comes before ProviderOptimizationStrategies. Thus, if the provider’s XXXGraphStepStrategy simply walks from the second V() looking for has()-only, it will not be able to pull in the has() cause the barrier() blocks it. Please see the updates to TinkerGraphStepStrategy and how it acknowledges NoOpBarrierSteps (i.e. barrier()) skipping over them and “left”-propagating labels to the previous step.

Configurable Strategies

If the provider has non-configurable TraversalStrategy classes, those classes should expose a static instance()-method. This is typical and thus, backwards compatible. However, if the provider has a TraversalStrategy that can be configured (e.g. via a Builder), then it should expose a static create(Configuration)-method, where the keys of the configuration are the method names of the Builder and the values are the method arguments. For instance, for Gremlin-Python to create a SubgraphStrategy, it does the following:

g = Graph().traversal().withRemote(connection).
        withStrategies(SubgraphStrategy(vertices=__.hasLabel('person'),edges=__.has('weight',gt(0.5))))

The SubgraphStrategy.create(Configuration)-method is defined as:

public static SubgraphStrategy create(final Configuration configuration) {
    final Builder builder = SubgraphStrategy.build();
    if (configuration.containsKey(VERTICES))
        builder.vertices((Traversal) configuration.getProperty(VERTICES));
    if (configuration.containsKey(EDGES))
        builder.edges((Traversal) configuration.getProperty(EDGES));
    if (configuration.containsKey(VERTEX_PROPERTIES))
        builder.vertexProperties((Traversal) configuration.getProperty(VERTEX_PROPERTIES));
    return builder.create();
}

Finally, in order to make serialization possible from JVM-based Gremlin language variants, all strategies have a TraverserStrategy.getConfiguration() method which returns a Configuration that can be used to create() the TraversalStrategy.

The SubgraphStrategy.getConfiguration()-method is defined as:

@Override
public Configuration getConfiguration() {
    final Map<String, Object> map = new HashMap<>();
    map.put(STRATEGY, SubgraphStrategy.class.getCanonicalName());
    if (null != this.vertexCriterion)
        map.put(VERTICES, this.vertexCriterion);
    if (null != this.edgeCriterion)
            map.put(EDGES, this.edgeCriterion);
    if (null != this.vertexPropertyCriterion)
        map.put(VERTEX_PROPERTIES, this.vertexPropertyCriterion);
    return new MapConfiguration(map);
}

The default implementation of TraversalStrategy.getConfiguration() is defined as:

public default Configuration getConfiguration() {
    return new BaseConfiguration();
}

Thus, if the provider does not have any "builder"-based strategies, then no updates to their strategies are required.

Deprecated elementNotFound

Both Graph.Exceptions.elementNotFound() methods have been deprecated. These exceptions were being asserted in the test suite but were not being used anywhere in gremlin-core itself. The assertions have been modified to simply assert that NoSuchElementException was thrown, which is precisely the behavior that was being indirectly asserted when Graph.Exceptions.elementNotFound() were being used.

Providers should not need to take any action in this case for their tests to pass, however, it would be wise to remove uses of these exception builders as they will be removed in the future.

Hidden Step Labels for Compilation Only

In order for SubgraphStrategy to work, it was necessary to have multi-level children communicate with one another via hidden step labels. It was decided that hidden step labels are for compilation purposes only and will be removed prior to traversal evaluation. This is a valid decision given that hidden labels for graph system providers are not allowed to be used by users. Likewise, hidden labels for steps should not be allowed be used by users as well.

PropertyMapStep with Selection Traversal

PropertyMapStep now supports selection of properties via child property traversal. If a provider was relying solely on the provided property keys in a ProviderOptimizationStrategy, they will need to check if there is a child traversal and if so, use that in their introspection for respective strategies. This model was created to support SubgraphStrategy.vertexProperties() filtering.

ConnectiveP Nesting Inlined

There was a bug in ConnectiveP (AndP/OrP), where eq(1).and(eq(2).and(eq(3))) was AndP(eq(1),AndP(eq(2),eq(3))) instead of unnested/inlined as AndP(eq(1),eq(2),eq(3)). Likewise, for OrP. If a provider was leveraging ConnectiveP predicates for their custom steps (e.g. graph- or vertex-centric index lookups), then they should be aware of the inlining and can simplify any and/or-tree walking code in their respective ProviderOptimizationStrategy.

TinkerPop 3.2.2

Release Date: September 6, 2016

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

GraphSON 2.0

GraphSON 2.0 has been introduced to improve and normalize the format of types embedded in GraphSON.

Log4j Dependencies

There were a number of changes to the Log4j dependencies in the various modules. Log4j was formerly included as part of the slf4j-log4j12 in gremlin-core, however that "forced" use of Log4j as a logger implementation when that really wasn’t necessary or desired. If a project depended on gremlin-core or other TinkerPop project to get its Log4j implementation then those applications will need to now include the dependency themselves directly.

Note that Gremlin Server and Gremlin Console explicitly package Log4j in their respective binary distributions.

Default for gremlinPool

The gremlinPool setting in Gremlin Server is now defaulted to zero. When set to zero, Gremlin Server will use the value provided by Runtime.availableProcessors() to set the pool size. Note that the packaged YAML files no longer contain the thread pool settings as all are now driven by sensible defaults. Obviously these values can be added and overridden as needed.

New Console Features

The Gremlin Console can now have its text colorized. For example, you can set the color of the Gremlin ascii art to the more natural color of green by using the :set command:

gremlin> :set gremlin.color green

It is also possible to colorize results, like vertices, edges, and other common returns. Please see the reference documentation for more details on all the settings.

The console also now includes better multi-line support:

gremlin> g.V().out().
......1>       has('name','josh').
......2>       out('created')
==>v[5]
==>v[3]

This is a nice feature in that it can help you understand if a line is incomplete and unevaluated.

REST API Renamed to HTTP API

This is only a rename to clarify the design of the API. There is no change to the API itself.

Upgrading for Providers

Important
It is recommended that providers also review all the upgrade instructions specified for users. Many of the changes there may prove important for the provider’s implementation.

Graph System Providers

Deprecated Io.Builder.registry()

The Io.Builder.registry() has been deprecated in favor of Io.Builder.onMapper(Consumer<Mapper>). This change gives the Graph implementation greater flexibility over how to modify the Mapper implementation. In most cases, the implementation will simply add its IoRegistry to allow the Mapper access to custom serialization classes, but this approach makes it possible to also set other specific settings that aren’t generalized across all IO implementations. A good example of this type of usage would be to provide a custom ClassRessolver implementation to a GryoMapper.

Log4j Dependencies

There were a number of changes to the Log4j dependencies in the various modules. Log4j was formerly included as part of the slf4j-log4j12 in gremlin-core, however that "forced" use of log4j as a logger implementation when that really wasn’t necessary or desired. The slf4j-log4j12 dependency is now in "test" scope for most of the modules. The exception to that rule is gremlin-test which prescribes it as "optional". That change means that developers dependending on gremlin-test (or gremlin-groovy-test) will need to explicitly specify it as a dependency in their pom.xml (or a different slf4j implementation if that better suits them).

Drivers Providers

GraphSON 2.0

Drivers providers can exploit the new format of typed values JSON serialization offered by GraphSON 2.0. This format has been created to allow easy and agnostic parsing of a GraphSON payload without type loss. Drivers of non-Java languages can then implement their own mapping of the GraphSON’s language agnostic type IDs (e.g. UUID, LocalDate) to the appropriate representation for the driver’s language.

Traversal Serialization

There was an "internal" serialization format in place for Traversal which allowed one to be submitted to Gremlin Server directly over RemoteGraph. That format has been removed completely and is wholly replaced by the non-JVM specific approach of serializing Bytecode.

TinkerPop 3.2.1

Release Date: July 18, 2016

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

Gephi Plugin

The Gephi Plugin has been updated to support Gephi 0.9.x. Please upgrade to this latest version to use the Gephi Plugin for Gremlin Console.

GryoMapper Construction

It is now possible to override existing serializers with calls to addCustom on the GryoMapper builder. This option allows complete control over the serializers used by Gryo. Of course, this also makes it possible to produce completely non-compliant Gryo files. This feature should be used with caution.

TraversalVertexProgram

TraversalVertexProgram always maintained a HALTED_TRAVERSERS TraverserSet for each vertex throughout the life of the OLAP computation. However, if there are no halted traversers in the set, then there is no point in keeping that compute property around as without it, time and space can be saved. Users that have VertexPrograms that are chained off of TraversalVertexProgram and have previously assumed that HALTED_TRAVERSERS always exists at each vertex, should no longer assume that.

TraverserSet haltedTraversers = vertex.value(TraversalVertexProgram.HALTED_TRAVERSERS);
// good code
TraverserSet haltedTraversers = vertex.property(TraversalVertexProgram.HALTED_TRAVERSERS).orElse(new TraverserSet());

Interrupting Traversals

Traversals now better respect calls to Thread.interrupt(), which mean that a running Traversal can now be cancelled. There are some limitations that remain, but most OLTP-based traversals should cancel without issue. OLAP-based traversals for Spark will also cancel and clean up running jobs in Spark itself. Mileage may vary on other process implementations and it is possible that graph providers could potentially write custom step implementations that prevent interruption. If it is found that there are configurations or specific traversals that do not respect interruption, please mention them on the mailing list.

Gremlin Console Flags

Gremlin Console had several methods for executing scripts from file at the start-up of bin/gremlin.sh. There were two options:

bin/gremlin.sh script.groovy    1
bin/gremlin.sh -e script.groovy 2
  1. The script.groovy would be executed as a console initialization script setting the console up for use and leaving it open when the script completed successfully or closing it if the script failed.

  2. The script.groovy would be executed by the ScriptExecutor which meant that commands for the Gremlin Console, such as :remote and :> would not be respected.

Changes in this version of TinkerPop have added much more flexibility here and only a minor breaking change should be considered when using this version. First of all, recognize that hese two lines are currently equivalent:

bin/gremlin.sh script.groovy
bin/gremlin.sh -i script.groovy

but users should start to explicitly specify the -i flag as TinkerPop will eventually remove the old syntax. Despite the one used beware of the fact that neither will close the console on script failure anymore. In that sense, this behavior represents a breaking change to consider. To ensure the console closes on failure or success, a script will have to use the -e option.

The console also has a number of new features in addition to -e and -i:

  • View the available flags for the console with -h.

  • Control console output with -D, -Q and -V

  • Get line numbers on script failures passed to -i and -e.

Upgrading for Providers

Important
It is recommended that providers also review all the upgrade instructions specified for users. Many of the changes there may prove important for the provider’s implementation.

Graph System Providers

VertexComputing API Change

The VertexComputing API is used by steps that wrap a VertexProgram. There is a method called VertexComputing.generateProgram() that has changed which now takes a second argument of Memory. To upgrade, simply fix the method signature of your VertexComputing implementations. The Memory argument can be safely ignored to effect the exact same semantics as prior. However, now previous OLAP job Memory can be leveraged when constructing the next VertexProgram in an OLAP traversal chain.

Interrupting Traversals

Several tests have been added to the TinkerPop test suite to validate that a Traversal can be cancelled with Thread.interrupt(). The test suite does not cover all possible traversal scenarios. When implementing custom steps, providers should take care to not ignore an InterruptionException that might be thrown in their code and to be sure to check Thread.isInterrupted() as needed to ensure that the step remains cancellation compliant.

Performance Tests

All "performance" tests have been deprecated. In the previous 3.2.0-incubating release, the ProcessPerformanceSuite and TraversalPerformanceTest were deprecated, but some other tests remained. It is the remaining tests that have been deprecated on this release:

  • `StructurePerformanceSuite

    • GraphReadPerformanceTest

    • GraphWriterPerformanceTest

  • GroovyEnvironmentPerformanceSuite

    • SugarLoaderPerformanceTest

    • GremlinExecutorPerformanceTest

  • Gremlin Server related performance tests

  • TinkerGraph related performance tests

Providers should implement their own performance tests and not rely on these deprecated tests as they will be removed in a future release along with the "JUnit Benchmarks" dependency.

Graph Database Providers

Transaction Tests

Tests and assertions were added to the structure test suite to validate that transaction status was in the appropriate state following calls to close the transaction with commit() or rollback(). It is unlikely that this change would cause test breaks for providers, unless the transaction status was inherently disconnected from calls to close the transaction somehow.

In addition, other tests were added to enforce the expected semantics for threaded transactions. Threaded transactions are expected to behave like manual transactions. They should be open automatically when they are created and once closed should no longer be used. This behavior is not new and is the typical expected method for working with these types of transactions. The test suite just requires that the provider implementation conform to these semantics.

GraphFilter and GraphFilterStrategy

GraphFilter has been significantly advanced where the determination of an edge direction/label legality is more stringent. Along with this, GraphFilter.getLegallyPositiveEdgeLabels() has been added as a helper method to make it easier for GraphComputer providers to know the space of labels being accessed by the traversal and thus, better enable provider-specific push-down predicates.

Note that GraphFilterStrategy is now a default TraversalStrategy registered with GraphComputer. If GraphFilter is expensive for the underlying GraphComputer implementation, it can be deactivated as is done for TinkerGraphComputer.

static {
  TraversalStrategies.GlobalCache.registerStrategies(TinkerGraphComputer.class,
    TraversalStrategies.GlobalCache.getStrategies(GraphComputer.class).clone().removeStrategies(GraphFilterStrategy.class));
}

Graph Language Providers

VertexTest Signatures

The method signatures of get_g_VXlistXv1_v2_v3XX_name and get_g_VXlistX1_2_3XX_name of VertexTest were changed to take arguments for the Traversal to be constructed by extending classes.

TinkerPop 3.2.0

Release Date: Release Date: April 8, 2016

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

Hadoop FileSystem Variable

The HadoopGremlinPlugin defines two variables: hdfs and fs. The first is a reference to the HDFS FileSystemStorage and the latter is a reference to the local FileSystemStorage. Prior to 3.2.x, fs was called local. However, there was a variable name conflict with Scope.local. As such local is now fs. This issue existed prior to 3.2.x, but was not realized until this release. Finally, this only effects Gremlin Console users.

Hadoop Configurations

Note that gremlin.hadoop.graphInputFormat, gremlin.hadoop.graphOutputFormat, gremlin.spark.graphInputRDD, and gremlin.spark.graphOuputRDD have all been deprecated. Using them still works, but moving forward, users only need to leverage gremlin.hadoop.graphReader and gremlin.hadoop.graphWriter. An example properties file snippet is provided below.

gremlin.graph=org.apache.tinkerpop.gremlin.hadoop.structure.HadoopGraph
gremlin.hadoop.graphReader=org.apache.tinkerpop.gremlin.hadoop.structure.io.gryo.GryoInputFormat
gremlin.hadoop.graphWriter=org.apache.tinkerpop.gremlin.hadoop.structure.io.gryo.GryoOutputFormat
gremlin.hadoop.jarsInDistributedCache=true
gremlin.hadoop.defaultGraphComputer=org.apache.tinkerpop.gremlin.spark.process.computer.SparkGraphComputer

TraversalSideEffects Update

There were changes to TraversalSideEffect both at the semantic level and at the API level. Users that have traversals of the form sideEffect{…​} that leverage global side-effects should read the following carefully. If the user’s traversals do not use lambda-based side-effect steps (e.g. groupCount("m")), then the changes below will not effect them. Moreover, if user’s traversal only uses sideEffect{…​} with closure (non-TraversalSideEffect) data references, then the changes below will not effect them. If the user’s traversal uses sideEffects in OLTP only, the changes below will not effect them. Finally, providers should not be effected by the changes save any tests cases.

TraversalSideEffects Get API Change

TraversalSideEffects can now logically operate within a distributed OLAP environment. In order to make this possible, it is necessary that each side-effect be registered with a reducing BinaryOperator. This binary operator will combine distributed updates into a single global side-effect at the master traversal. Many of the methods in TraversalSideEffect have been Deprecated, but they are backwards compatible save that TraversalSideEffects.get() no longer returns an Optional, but instead throws an IllegalArgumentException. While the Optional semantics could have remained, it was deemed best to directly return the side-effect value to reduce object creation costs and because all side-effects must be registered apriori, there is never a reason why an unknown side-effect key would be used. In short:

// change
traversal.getSideEffects().get("m").get()
// to
traversal.getSideEffects().get("m")
TraversalSideEffects Registration Requirement

All TraversalSideEffects must be registered upfront. This is because, in OLAP, side-effects map to Memory compute keys and as such, must be declared prior to the execution of the TraversalVertexProgram. If a user’s traversal creates a side-effect mid-traversal, it will fail. The traversal must use GraphTraversalSource.withSideEffect() to declare the side-effects it will use during its execution lifetime. If the user’s traversals use standard side-effect Gremlin steps (e.g. group("m")), then no changes are required.

TraversalSideEffects Add Requirement

In a distributed environment, a side-effect can not be mutated and be expected to exist in the mutated form at the final, aggregated, master traversal. For instance, if the side-effect "myCount" references a Long, the Long can not be updated directly via sideEffects.set("myCount", sideEffects.get("myCount") + 1). Instead, it must rely on the registered reducer to do the merging and thus, the Step must do sideEffect.add("mySet",1), where the registered reducer is Operator.sum. Thus, the below will increment "a". If no operator was provided, then the operator is assumed Operator.assign and the final result of "a" would be 1. Note that Traverser.sideEffects(key,value) uses TraversalSideEffect.add().

gremlin> traversal = g.withSideEffect('a',0,sum).V().out().sideEffect{it.sideEffects('a',1)}
==>v[3]
==>v[2]
==>v[4]
==>v[5]
==>v[3]
==>v[3]
gremlin> traversal.getSideEffects().get('a')
==>6
gremlin> traversal = g.withSideEffect('a',0).V().out().sideEffect{it.sideEffects('a',1)}
==>v[3]
==>v[2]
==>v[4]
==>v[5]
==>v[3]
==>v[3]
gremlin> traversal.getSideEffects().get('a')
==>1

ProfileStep Update and GraphTraversal API Change

The profile()-step has been refactored into 2 steps — ProfileStep and ProfileSideEffectStep. Users who previously used the profile() in conjunction with cap(TraversalMetrics.METRICS_KEY) can now simply omit the cap step. Users who retrieved TraversalMetrics from the side-effects after iteration can still do so, but will need to specify a side-effect key when using the profile(). For example, profile("myMetrics").

BranchStep Bug Fix

There was a bug in BranchStep that also rears itself in subclass steps such as UnionStep and ChooseStep. For traversals with branches that have barriers (e.g. count(), max(), groupCount(), etc.), the traversal needs to be updated. For instance, if a traversal is of the form g.V().union(out().count(),both().count()), the result is now different (the bug fix yields a different output). In order to yield the same result, the traversal should be rewritten as g.V().local(union(out().count(),both().count())). Note that if a branch does not have a barrier, then no changes are required. For instance, g.V().union(out(),both()) does not need to be updated. Moreover, if the user’s traversal already used the local()-form, then no change are required either.

MemoryComputeKey and VertexComputeKey

Users that have custom VertexProgram implementations will need to change their implementations to support the new VertexComputeKey and MemoryComputeKey classes. In the VertexPrograms provided by TinkerPop, these changes were trivial, taking less than 5 minutes to make all the requisite updates.

  • VertexProgram.getVertexComputeKeys() returns a Set<VertexComputeKey>. No longer a Set<String>. Use VertexComputeKey.of(String key,boolean transient) to generate a VertexComputeKey. Transient keys were not supported in the past, so to make the implementation semantically equivalent, the boolean transient should be false.

  • VertexProgram.getMemoryComputeKeys() returns a Set<MemoryComputeKey>. No longer a Set<String>. Use MemoryComputeKey.of(String key, BinaryOperator reducer, boolean broadcast, boolean transient) to generate a MemoryComputeKey. Broadcasting and transients were not supported in the past so to make the implementation semantically equivalent, the boolean broadcast should be true and the boolean transient should be false.

An example migration looks as follows. What might currently look like:

public Set<String> getMemoryComputeKeys() {
   return new HashSet<>(Arrays.asList("a","b","c"))
}

Should now look like:

public Set<MemoryComputeKey> getMemoryComputeKeys() {
  return new HashSet<>(Arrays.asList(
    MemoryComputeKey.of("a", Operator.and, true, false),
    MemoryComputeKey.of("b", Operator.sum, true, false),
    MemoryComputeKey.of("c", Operator.or, true, false)))
}

A similar patterns should also be used for VertexProgram.getVertexComputeKeys().

SparkGraphComputer and GiraphGraphComputer Persistence

The MapReduce-based steps in TraversalVertexProgram have been removed and replaced using a new Memory-reduction model. MapReduce jobs always created a persistence footprint, e.g. in HDFS. Memory data was never persisted to HDFS. As such, there will be no data on the disk that is accessible. For instance, there is no more ~reducing, ~traversers, and specially named side-effects such as m from a groupCount('m'). The data is still accessible via ComputerResult.memory(), it simply does not have a corresponding on-disk representation.

RemoteGraph

RemoteGraph is a lightweight Graph implementation that acts as a proxy for sending traversals to Gremlin Server for remote execution. It is an interesting alternative to the other methods for connecting to Gremlin Server in that all other methods involved construction of a String representation of the Traversal which is then submitted as a script to Gremlin Server (via driver or HTTP).

gremlin> graph = RemoteGraph.open('conf/remote-graph.properties')
==>remotegraph[DriverServerConnection-localhost/127.0.0.1:8182 [graph='graph]]
gremlin> g = graph.traversal()
==>graphtraversalsource[remotegraph[DriverServerConnection-localhost/127.0.0.1:8182 [graph='graph]], standard]
gremlin> g.V().valueMap(true)
==>[name:[marko], label:person, id:1, age:[29]]
==>[name:[vadas], label:person, id:2, age:[27]]
==>[name:[lop], label:software, id:3, lang:[java]]
==>[name:[josh], label:person, id:4, age:[32]]
==>[name:[ripple], label:software, id:5, lang:[java]]
==>[name:[peter], label:person, id:6, age:[35]]

Note that g.V().valueMap(true) is executing in Gremlin Server and not locally in the console.

Upgrading for Providers

Important
It is recommended that providers also review all the upgrade instructions specified for users. Many of the changes there may prove important for the provider’s implementation.

Graph System Providers

GraphStep Compilation Requirement

OLTP graph providers that have a custom GraphStep implementation should ensure that g.V().hasId(x) and g.V(x) compile to the same representation. This ensures a consistent user experience around random access of elements based on ids (as opposed to potentially the former doing a linear scan). A static helper method called GraphStep.processHasContainerIds() has been added. TinkerGraphStepStrategy was updated as such:

((HasContainerHolder) currentStep).getHasContainers().forEach(tinkerGraphStep::addHasContainer);

is now

((HasContainerHolder) currentStep).getHasContainers().forEach(hasContainer -> {
  if (!GraphStep.processHasContainerIds(tinkerGraphStep, hasContainer))
    tinkerGraphStep.addHasContainer(hasContainer);
});
Step API Update

The Step interface is fundamental to Gremlin. Step.processNextStart() and Step.next() both returned Traverser<E>. We had so many Traverser.asAdmin() and direct typecast calls throughout (especially in TraversalVertexProgram) that it was deemed prudent to have Step.processNextStart() and Step.next() return Traverser.Admin<E>. Moreover it makes sense as this is internal logic where Admins are always needed. Providers with their own step definitions will simply need to change the method signatures of Step.processNextStart() and Step.next(). No logic update is required — save that asAdmin() can be safely removed if used. Also, Step.addStart() and Step.addStarts() take Traverser.Admin<S> and Iterator<Traverser.Admin<S>>, respectively.

Traversal API Update

The way in which TraverserRequirements are calculated has been changed (for the better). The ramification is that post compilation requirement additions no longer make sense and should not be allowed. To enforce this, Traversal.addTraverserRequirement() method has been removed from the interface. Moreover, providers/users should never be able to add requirements manually (this should all be inferred from the end compilation). However, if need be, there is always RequirementStrategy which will allow the provider to add a requirement at strategy application time (though again, there should not be a reason to do so).

ComparatorHolder API Change

Providers that either have their own ComparatorHolder implementation or reason on OrderXXXStep will need to update their code. ComparatorHolder now returns List<Pair<Traversal,Comparator>>. This has greatly reduced the complexity of comparison-based steps like OrderXXXStep. However, its a breaking API change that is trivial to update to, just some awareness is required.

GraphComputer Semantics and API

Providers that have a custom GraphComputer implementation will have a lot to handle. Note that if the graph system simply uses SparkGraphComputer or GiraphGraphComputer provided by TinkerPop, then no updates are required. This only effects providers that have their own custom GraphComputer implementations.

Memory updates:

  • Any BinaryOperator can be used for reduction and is made explicit in the MemoryComputeKey.

  • MemoryComputeKeys can be marked transient and must be removed from the resultant ComputerResult.memory().

  • MemoryComputeKeys can be specified to not broadcast and thus, must not be available to workers to read in VertexProgram.execute().

  • The Memory API has been changed. No more incr(), and(), etc. Now its just set() (setup/terminate) and add() (execute).

VertexProgram updates:

  • VertexComputeKeys can be marked transient and must be removed from the resultant ComputerResult.graph().

Operational semantic test cases have been added to GraphComputerTest to ensure that all the above are implemented correctly.

Barrier Step Updates

The Barrier interface use to simply be a marker interface. Now it has methods and it is the primary means by which distributed steps across an OLAP job are aggregated and distributed. It is unlikely that Barrier was ever used directly by a provider’s custom step. Instead, a provider most likely extended SupplyingBarrierStep, CollectingBarrierStep, and/or ReducingBarrierStep.

Providers that have custom extensions to these steps or that use Barrier directly will need to adjust their implementation slightly to accommodate a new API that reflects the Memory updates above. This should be a simple change. Note that FinalGet no longer exists and such post-reduction processing is handled by the reducing step (via the new Generating interface).

Performance Tests

The ProcessPerformanceSuite and TraversalPerformanceTest have been deprecated. They are still available, but going forward, providers should implement their own performance tests and not rely on the built-in JUnit benchmark-based performance test suite.

Graph Processor Providers

GraphFilter and GraphComputer

The GraphComputer API has changed with the addition of GraphComputer.vertices(Traversal) and GraphComputer.edges(Traversal). These methods construct a GraphFilter object which is also new to TinkerPop 3.2.0. GraphFilter is a "push-down predicate" used to selectively retrieve subgraphs of the underlying graph to be OLAP processed.

  • If the graph system provider relies on an existing GraphComputer implementations such as SparkGraphComputer and/or GiraphGraphComputer, then there is no immediate action required on their part to remain TinkerPop-compliant. However, they may wish to update their InputFormat or InputRDD implementation to be GraphFilterAware and handle the GraphFilter filtering at the disk/database level. It is advisable to do so in order to reduce OLAP load times and memory/GC usage.

  • If the graph system provider has their own GraphComputer implementation, then they should implement the two new methods and ensure that GraphFilter is processed correctly. There is a new test case called GraphComputerTest.shouldSupportGraphFilter() which ensures the semantics of GraphFilter are handled correctly. For a "quick and easy" way to move forward, look to GraphFilterInputFormat as a way of wrapping an existing InputFormat to do filtering prior to VertexProgram or MapReduce execution.

Note
To quickly move forward, the GraphComputer implementation can simply set GraphComputer.Features.supportsGraphFilter() to false and ensure that GraphComputer.vertices() and GraphComputer.edges() throws GraphComputer.Exceptions.graphFilterNotSupported(). This is not recommended as its best to support GraphFilter.
Job Chaining and GraphComputer

TinkerPop 3.2.0 has integrated VertexPrograms into GraphTraversal. This means, that a single traversal can compile to multiple GraphComputer OLAP jobs. This requires that ComputeResults be chainable. There was never any explicit tests to verify if a provider’s GraphComputer could be chained, but now there are. Given a reasonable implementation, it is likely that no changes are required of the provider. However, to ensure the implementation is "reasonable" GraphComputerTests have been added.

  • For providers that support their own GraphComputer implementation, note that there is a new GraphComputerTest.shouldSupportJobChaining(). This tests verifies that the ComputerResult output of one job can be fed into the input of a subsequent job. Only linear chains are tested/required currently. In the future, branching DAGs may be required.

  • For providers that support their own GraphComputer implementation, note that there is a new GraphComputerTest.shouldSupportPreExistingComputeKeys(). When chaining OLAP jobs together, if an OLAP job requires the compute keys of a previous OLAP job, then the existing compute keys must be accessible. A simple 2 line change to SparkGraphComputer and TinkerGraphComputer solved this for TinkerPop. GiraphGraphComputer did not need an update as this feature was already naturally supported.

Graph Language Providers

ScriptTraversal

Providers that have custom Gremlin language implementations (e.g. Gremlin-Scala), there is a new class called ScriptTraversal which will handle script-based processing of traversals. The entire GroovyXXXTest-suite was updated to use this new class. The previous TraversalScriptHelper class has been deprecated so immediate upgrading is not required, but do look into ScriptTraversal as TinkerPop will be using it as a way to serialize "String-based traversals" over the network moving forward.

ByModulating and Custom Steps

If the provider has custom steps that leverage by()-modulation, those will now need to implement ByModulating. Most of the methods in ByModulating are default and, for most situations, only ByModulating.modulateBy(Traversal) needs to be implemented. Note that this method’s body will most like be identical the custom step’s already existing TraversalParent.addLocalChild(). It is recommended that the custom step not use TraversalParent.addLocalChild() as this method may be deprecated in a future release. Instead, barring any complex usages, simply rename the CustomStep.addLocalChild(Traversal) to CustomStep.modulateBy(Traversal).

TraversalEngine Deprecation and GraphProvider

The TraversalSource infrastructure has been completely rewritten. Fortunately for users, their code is backwards compatible. Unfortunately for graph system providers, a few tweaks to their implementation are in order.

  • If the graph system supports more than Graph.compute(), then implement GraphProvider.getGraphComputer().

  • For custom TraversalStrategy implementations, change traverser.getEngine().isGraphComputer() to TraversalHelper.onGraphComputer(Traversal).

  • For custom Steps, change implements EngineDependent to implements GraphComputing.

TinkerPop 3.1.0

gremlin gangster

A 187 On The Undercover Gremlinz

TinkerPop 3.1.8

Release Date: August 21, 2017

Please see the changelog for a complete list of all the modifications that are part of this release.

TinkerPop 3.1.7

Release Date: June 12, 2017

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

GraphML XSLT

There were some inconsistencies in the GraphML format supported in TinkerPop 2.x. These issues were corrected on the initial release of TinkerPop 3.0.0, but as a result, attempting to read GraphML from 2.x will end with an error. A newly added XSLT file in gremlin-core, called tp2-to-tp3-graphml.xslt, transforms 2.x GraphML into 3.x GraphML, making it possible easily read in legacy GraphML through a 3.x GraphMLReader.

TinkerPop 3.1.6

Release Date: February 3, 2017

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Providers

Driver Providers

Session Close Confirmation

When a session is closed, it now returns a confirmation in the form of a single NO CONTENT message. When the message arrives, it means that the server has already destroyed the session. Prior to this change, the request was somewhat one-way, in that the client could send the request and the server would silently honor it. The confirmation makes it a bit easier to ensure from the client perspective that the close did what it was supposed to do, allowing the client to proceed only when the server was fully complete with its work.

TinkerPop 3.1.5

Release Date: October 17, 2016

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

Java Driver and close()

There were a few problems noted around the close() of Cluster and Client instances, including issues that presented as system hangs. These issues have been resolved, however, it is worth noting that an unchecked exception that was thrown under a certain situation has changed as part of the bug fixes. When submitting an in-session request on a Client that was closed (or closing) an IllegalStateException is thrown. This replaces older functionality that threw a ConnectionException and relied logic far deeper in the driver to produce that error and had the potential to open additional resources despite the intention of the user to "close".

TinkerPop 3.1.4

Release Date: September 6, 2016

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

Gremlin Server Workers

In release 3.1.3, a recommendation was made to ensure that the threadPoolWorker setting for Gremlin Server was no less than 2 in cases where Gremlin Server was being used with sessions that accept parallel requests. In 3.1.4, that is no longer the case and a size of 1 remains acceptable even in that specific case.

TinkerPop 3.1.3

Release Date: July 18, 2016

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

Reserved Gremlin Server Keys

Gremlin Server has always considered certain binding keys (request parameters) as reserved, but that list has now expanded to be more inclusive all the static enums that are imported to the script engine. It is possible that those using Gremlin Server may have to rename their keys if they somehow successfully were using some of the now reserved terms in previous versions.

Remote Timeout

Disabling the timeout for a :remote to Gremlin Server was previously accomplished by setting the timeout to max as in:

:remote config timeout max

where max would set the timeout to be Integer.MAX_VALUE. While this feature is still supported, it has been deprecated in favor of the new configuration option of none, as in:

:remote config timeout none

The use of none completely disables the timeout rather than just setting an arbitrarily high one. Note that it is still possible to get a timeout on a request if the server timeout limits are reached. The console timeout value only refers to how long the console will wait for a response from the server before giving up. By default, the timeout is set to none.

Gremlin Server Workers

Past configuration recommendations for the threadPoolWorker setting on Gremlin Server stated this value could be safely set to 1 at the low end. A size of 1 is still valid for most cases, however, if Gremlin Server is being used with sessions that accept parallel requests, then this value should be no less than 2 or else certain scripts (i.e. those that block for an extended period of time) may cause Gremlin Server to lock up the session.

Upgrading for Providers

Important
It is recommended that providers also review all the upgrade instructions specified for users. Many of the changes there may prove important for the provider’s implementation.

Graph Database Providers

Property Keys and Hyphens

Graph providers should no longer rely on the test suite to validate that hyphens work for labels and property keys.

Vertex and Edge Counts

A large number of asserts for vertex and edge counts in the test suite were not being applied. This problem has been rectified, but could manifest as test errors for different implementations. The chances of the new assertions identifying previously unrecognized bugs seems slim however, as there are many other tests that validate these counts in other ways. If those were passing previously, then these new asserts should likely not pose a problem.

Test Feature Annotations

A large number of gremlin-test feature annotations were incorrect which caused test cases to run against graphs that did not support those features. The annotations have been fixed, but this opened the possibility that more test cases will run against the graph implementation. Providers should ensure that their graph features() are consistent with the capabilities of the graph implementation.

Graph Language Providers

AndTest Renaming

The get_g_V_andXhasXage_gt_27XoutE_count_gt_2X_name test in AndTest was improperly named and did not match the nature of the traversal it was providing. It has been renamed to: get_g_V_andXhasXage_gt_27XoutE_count_gte_2X_name.

Driver Providers

SASL Mechanism

Note that the Gremlin Driver for Java now passes a new parameter for SASL authentication called saslMechanism. This is an optional argument and does not represent a breaking change, but it does make the overall implementation more complete. While the default authentication implementations packaged with Gremlin Server don’t utilize this argument other implementations might, so the drivers should be able to pass it as per the SASL specification.

TinkerPop 3.1.2

Release Date: April 8, 2016

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

Aliasing Sessions

Calls to SessionedClient.alias() used to throw UnsupportedOperationException and it was therefore not possible to use that capability with a session. That method is now properly implemented and aliasing is allowed.

Remote Console

The :remote console command provides a way to avoid having to prefix the :> command to scripts when remoting. This mode of console usage can be convenient when working exclusively with a remote like Gremlin Server and there is only a desire to view the returned data and not to actually work with it locally in any way.

Console Remote Sessions

The :remote tinkerpop.server command now allows for a "session" argument to be passed to connect. This argument, tells the remote to configure it with a Gremlin Server session. In this way, the console can act as a window to script exception on the server and behave more like a standard "local" console when it comes to script execution.

TinkerPop Archetypes

TinkerPop now offers Maven archetypes, which provide example project templates to quickly get started with TinkerPop. The available archetypes are as follows:

  • gremlin-archetype-server - An example project that demonstrates the basic structure of a Gremlin Server project, how to connect with the Gremlin Driver, and how to embed Gremlin Server in a testing framework.

  • gremlin-archetype-tinkergraph - A basic example of how to structure a TinkerPop project with Maven.

Session Transaction Management

When connecting to a session with gremlin-driver, it is now possible to configure the Client instance so as to request that the server manage the transaction for each requests.

Cluster cluster = Cluster.open();
Client client = cluster.connect("sessionName", true);

Specifying true to the connect() method signifies that the client should make each request as one encapsulated in a transaction. With this configuration of client there is no need to close a transaction manually.

Session Timeout Setting

The gremlin-driver now has a setting called maxWaitForSessionClose that allows control of how long it will wait for an in-session connection to respond to a close request before it simply times-out and moves on. When that happens, the server will either eventually close the connection via at session expiration or at the time of shutdown.

Upgrading for Providers

Important
It is recommended that providers also review all the upgrade instructions specified for users. Many of the changes there may prove important for the provider’s implementation.

All Providers

Provider Documentation

Documentation related to the lower-level APIs used by a provider, that was formerly in the reference documentation, has been moved to its own documentation set that is now referred to as the Provider Documentation.

Graph System Providers

GraphProvider.clear() Semantics

The semantics of the various clear() methods on GraphProvider didn’t really change, but it would be worth reviewing their implementations to ensure that implementations can be called successfully in an idempotent fashion. Multiple calls to clear() may occur for a single test on the same Graph instance, as 3.1.1-incubating introduced an automated method for clearing graphs at the end of a test and some tests call clear() manually.

Driver Providers

Session Transaction Management

Up until now transaction management has been a feature of sessionless requests only, but the new manageTransaction request argument for the Session OpProcessor changes that. Session-based requests can now pass this boolean value on each request to signal to Gremlin Server that it should attempt to commit (or rollback) the transaction at the end of the request. By default, this value as false, so there is no change to the protocol for this feature.

scriptEvalTimeout Override

The Gremlin Server protocol now allows the passing of scriptEvaluationTimeout as an argument to the SessionOpProcessor and the StandardOpProcessor. This value will override the setting of the same name provided in the Gremlin Server configuration file on a per request basis.

Plugin Providers

RemoteAcceptor allowRemoteConsole

The RemoteAcceptor now has a new method called allowRemoteConsole(). It has a default implementation that returns false and should thus be a non-breaking change for current implementations. This value should only be set to true if the implementation expects the user to always use :> to interact with it. For example, the tinkerpop.server plugin expects all user interaction through :>, where the line is sent to Gremlin Server. In that case, that RemoteAcceptor implementation can return true. On the other hand, the tinkerpop.gephi plugin, expects that the user sometimes call :> and sometimes work with local evaluation as well. It interacts with the local variable bindings in the console itself. For tinkerpop.gephi, this method returns false.

TinkerPop 3.1.1

Release Date: February 8, 2016

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

Storage I/O

The gremlin-core io-package now has a Storage interface. The methods that were available via hdfs (e.g. rm(), ls(), head(), etc.) are now part of Storage. Both HDFS and Spark implement Storage via FileSystemStorage and SparkContextStorage, respectively. SparkContextStorage adds support for interacting with persisted RDDs in the Spark cache.

This update changed a few of the file handling methods. As it stands, these changes only effect manual Gremlin Console usage as HDFS support was previously provided via Groovy meta-programing. Thus, these are not "code-based" breaking changes.

  • hdfs.rmr() no longer exists. hdfs.rm() is now recursive. Simply change all references to rmr() to rm() for identical behavior.

  • hdfs.head(location,lines,writableClass) no longer exists.

    • For graph locations, use hdfs.head(location,writableClass,lines).

    • For memory locations, use hdfs.head(location,memoryKey,writableClass,lines).

  • hdfs.head(…​,ObjectWritable) no longer exists. Use SequenceFileInputFormat as an input format is the parsing class.

Given that HDFS (and now Spark) interactions are possible via Storage and no longer via Groovy meta-programming, developers can use these Storage implementations in their Java code. In fact, Storage has greatly simplified complex file/RDD operations in both GiraphGraphComputer and SparkGraphComputer.

Finally, note that the following low-level/internal classes have been removed: HadoopLoader and HDFSTools.

Gremlin Server Transaction Management

Gremlin Server now has a setting called strictTransactionManagement, which forces the user to pass aliases for all requests. The aliases are then used to determine which graphs will have their transactions closed for that request. The alternative is to continue with default operations where the transactions of all configured graphs will be closed. It is likely that strictTransactionManagement (which is false by default so as to be backward compatible with previous versions) will become the future standard mode of operation for Gremlin Server as it provides a more efficient method for transaction management.

Deprecated credentialsDbLocation

The credentialsDbLocation setting was a TinkerGraph only configuration option to the SimpleAuthenticator for Gremlin Server. It provided the file system location to a "credentials graph" that TinkerGraph would read from a Gryo file at that spot. This setting was only required because TinkerGraph did not support file persistence at the time that SimpleAuthenticator was created.

As of 3.1.0-incubating, TinkerGraph received a limited persistence feature that allowed the "credentials graph" location to be specified in the TinkerGraph properties file via gremlin.tinkergraph.graphLocation and as such the need for credentialsDbLocation was eliminated.

This deprecation is not a breaking change, however users should be encouraged to convert their configurations to use the gremlin.tinkergraph.graphLocation as soon as possible, as the deprecated setting will be removed in a future release.

TinkerGraph Supports Any I/O

TinkerGraph’s 'gremlin.tinkergraph.graphLocation' configuration setting can now take a fully qualified class name of a Io.Builder implementation, which means that custom IO implementations can be used to read and write TinkerGraph instances.

Authenticator Method Deprecation

For users who have a custom Authenticator implementation for Gremlin Server, there will be a new method present:

public default SaslNegotiator newSaslNegotiator(final InetAddress remoteAddress)

Implementation of this method is now preferred over the old method with the same name that has no arguments. The old method has been deprecated. This is a non-breaking change as the new method has a default implementation that simply calls the old deprecated method. In this way, existing Authenticator implementations will still work.

Spark Persistence Updates

Spark RDD persistence is now much safer with a "job server" system that ensures that persisted RDDs are not garbage collected by Spark. With this, the user is provider a spark object that enables them to manage persisted RDDs much like the hdfs object is used for managing files in HDFS.

Finally, InputRDD instance no longer need a reduceByKey() postfix as view merges happen prior to writing the graphRDD. Note that a reduceByKey() postfix will not cause problems if continued, it is simply inefficient and no longer required.

Logging

Logging to Gremlin Server and Gremlin Console can now be consistently controlled by the log4j-server.properties and log4j-console.properties which are in the respective conf/ directories of the packaged distributions.

Gremlin Server Sandboxing

A number of improvements were made to the sandboxing feature of Gremlin Server (more specifically the GremlinGroovyScriptEngine). A new base class for sandboxing was introduce with the AbstractSandboxExtension, which makes it a bit easier to build white list style sandboxes. A usable implementation of this was also supplied with the FileSandboxExtension, which takes a configuration file containing a white list of accessible methods and variables that can be used in scripts. Note that the original SandboxExtension has been deprecated in favor of the AbsstractSandboxExtension or extending directly from Groovy’s TypeCheckingDSL.

Deprecated supportsAddProperty()

It was realized that VertexPropertyFeatures.supportsAddProperty() was effectively a duplicate of VertexFeatures.supportsMetaProperties(). As a result, supportsAddProperty() was deprecated in favor of the other. If using supportsAddProperty(), simply modify that code to instead utilize supportsMetaProperties().

Upgrading for Providers

Important
It is recommended that providers also review all the upgrade instructions specified for users. Many of the changes there may prove important for the provider’s implementation.

Graph System Providers

Data Types in Tests

There were a number of fixes related to usage of appropriate types in the test suite. There were cases where tests were mixing types, such that a single property key might have two different values. This mixed typing caused problems for some graphs and wasn’t really something TinkerPop was looking to explicitly enforce as a rule of implementing the interfaces.

While the changes should not have been breaking, providers should be aware that improved consistencies in the tests may present opportunities for test failures.

Graph Database Providers

Custom ClassResolver

For providers who have built custom serializers in Gryo, there is a new feature open that can be considered. A GryoMapper can now take a custom Kryo ClassResolver, which means that custom types can be coerced to other types during serialization (e.g. a custom identifier could be serialized as a HashMap). The advantage to taking this approach is that users will not need to have the provider’s serializers on the client side. They will only need to exist on the server (presuming that the a type is coerced to a type available on the client, of course). The downside is that serialization is then no longer a two way street. For example, a custom ClassResolver that coerced a custom identifier to HashMap would let the client work with the identifier as a HashMap, but the client would then have to send that identifier back to the server as a HashMap where it would be recognized as a HashMap (not an identifier).

Feature Consistency

There were a number of corrections made around the consistency of Features and how they were applied in tests. Corrections fell into two groups of changes:

  1. Bugs in the how Features were applied to certain tests.

  2. Refactoring around the realization that VertexFeatures.supportsMetaProperties() is really just a duplicate of features already exposed as VertexPropertyFeatures.supportsAddProperty(). VertexPropertyFeatures.supportsAddProperty() has been deprecated.

These changes related to "Feature Consistency" open up a number of previously non-executing tests for graphs that did not support meta-properties, so providers should be wary of potential test failure on previously non-executing tests.

Graph Processor Providers

InputRDD and OutputRDD Updates

There are two new methods on the Spark-Gremlin RDD interfaces.

  • InputRDD.readMemoryRDD(): get a ComputerResult.memory() from an RDD.

  • OutputRDD.writeMemoryRDD(): write a ComputerResult.memory() to an RDD.

Note that both these methods have default implementations which simply work with empty RDDs. Most providers will never need to implement these methods as they are specific to file/RDD management for GraphComputer. The four classes that implement these methods are PersistedOutputRDD, PersistedInputRDD, InputFormatRDD, and OutputFormatRDD. For the interested provider, study the implementations therein to see the purpose of these two new methods.

TinkerPop 3.1.0

Release Date: November 16, 2015

Please see the changelog for a complete list of all the modifications that are part of this release.

Additional upgrade information can be found here:

Upgrading for Users

Shading Jackson

The Jackson library is now shaded to gremlin-shaded, which will allow Jackson to version independently without breaking compatibility with dependent libraries or with those who depend on TinkerPop. The downside is that if a library depends on TinkerPop and uses the Jackson classes, those classes will no longer exist with the standard Jackson package naming. They will have to shifted as follows:

  • org.objenesis becomes org.apache.tinkerpop.shaded.objenesis

  • com.esotericsoftware.minlog becomes org.apache.tinkerpop.shaded.minlog

  • com.fasterxml.jackson becomes org.apache.tinkerpop.shaded.jackson

PartitionStrategy and VertexProperty

PartitionStrategy now supports partitioning within VertexProperty. The Graph needs to be able to support meta-properties for this feature to work.

Gremlin Server and Epoll

Gremlin Server provides a configuration option to turn on support for Netty native transport on Linux, which has been shown to help improve performance.

Rebindings Deprecated

The notion of "rebindings" has been deprecated in favor of the term "aliases". Alias is a better and more intuitive term than rebindings which should make it easier for newcomers to understand what they are for.

Configurable Driver Channelizer

The Gremlin Driver now allows the Channerlizer to be supplied as a configuration, which means that custom implementations may be supplied.

GraphSON and Strict Option

The GraphMLReader now has a strict option on the Builder so that if a data type for a value is invalid in some way, GraphMLReader will simply skip that problem value. In that way, it is a bit more forgiving than before especially with empty data.

Transaction.close() Default Behavior

The default behavior of Transaction.close() is to rollback the transaction. This is in contrast to previous versions where the default behavior was commit. Using rollback as the default should be thought of as a like a safer approach to closing where a user must now explicitly call commit() to persist their mutations.

See TINKERPOP-805 for more information.

ThreadLocal Transaction Settings

The Transaction.onReadWrite() and Transaction.onClose() settings now need to be set for each thread (if another behavior than the default is desired). For gremlin-server users that may be changing these settings via scripts. If the settings are changed for a sessionless request they will now only apply to that one request. If the settings are changed for an in-session request they will now only apply to all future requests made in the scope of that session.

Hadoop-Gremlin

  • Hadoop1 is no longer supported. Hadoop2 is now the only supported Hadoop version in TinkerPop.

  • Spark and Giraph have been split out of Hadoop-Gremlin into their own respective packages (Spark-Gremlin and Giraph-Gremlin).

  • The directory where application jars are stored in HDFS is now hadoop-gremlin-3.5.0-SNAPSHOT-libs.

    • This versioning is important so that cross-version TinkerPop use does not cause jar conflicts.

See link:https://issues.apache.org/jira/browse/TINKERPOP-616

Spark-Gremlin

  • Providers that wish to reuse a graphRDD can leverage the new PersistedInputRDD and PersistedOutputRDD.

    • This allows the graphRDD to avoid serialization into HDFS for reuse. Be sure to enabled persisted SparkContext (see documentation).

See link:https://issues.apache.org/jira/browse/TINKERPOP-868, link:https://issues.apache.org/jira/browse/TINKERPOP-925

TinkerGraph Serialization

TinkerGraph is serializable over Gryo, which means that it can shipped over the wire from Gremlin Server. This feature can be useful when working with remote subgraphs.

Deprecation in TinkerGraph

The public static String configurations have been renamed. The old public static variables have been deprecated. If the deprecated variables were being used, then convert to the replacements as soon as possible.

Deprecation in Gremlin-Groovy

The closure wrappers classes GFunction, GSupplier, GConsumer have been deprecated. In Groovy, a closure can be specified using as Function and thus, these wrappers are not needed. Also, the GremlinExecutor.promoteBindings() method which was previously deprecated has been removed.

Gephi Traversal Visualization

The process for visualizing a traversal has been simplified. There is no longer a need to "name" steps that will represent visualization points for Gephi. It is possible to just "configure" a visualTraversal in the console:

gremlin> :remote config visualTraversal graph vg

which creates a special TraversalSource from graph called vg. The traversals created from vg can be used to :submit to Gephi.

Alterations to GraphTraversal

There were a number of changes to GraphTraversal. Many of the changes came by way of deprecation, but some semantics have changed as well:

  • ConjunctionStrategy has been renamed to ConnectiveStrategy (no other behaviors changed).

  • ConjunctionP has been renamed to ConnectiveP (no other behaviors changed).

  • DedupBijectionStrategy has been renamed (and made more effective) as FilterRankingStrategy.

  • The GraphTraversal mutation API has change significantly with all previous methods being supported but deprecated.

    • The general pattern used now is addE('knows').from(select('a')).to(select('b')).property('weight',1.0).

  • The GraphTraversal sack API has changed with all previous methods being supported but deprecated.

    • The old sack(mult,'weight') is now sack(mult).by('weight').

  • GroupStep has been redesigned such that there is now only a key- and value-traversal. No more reduce-traversal.

    • The previous group()-methods have been renamed to groupV3d0(). To immediately upgrade, rename all your group()-calls to groupV3d0().

    • To migrate to the new group()-methods, what was group().by('age').by(outE()).by(sum(local)) is now group().by('age').by(outE().sum()).

  • There was a bug in fold(), where if a bulked traverser was provided, the traverser was only represented once.

    • This bug fix might cause a breaking change to a user query if the non-bulk behavior was being counted on. If so, used dedup() prior to fold().

  • Both GraphTraversal().mapKeys() and GraphTraversal.mapValues() has been deprecated.

    • Use select(keys) and select(columns). However, note that select() will not unroll the keys/values. Thus, mapKeys()select(keys).unfold().

  • The data type of Operator enums will now always be the highest common data type of the two given numbers, rather than the data type of the first number, as it’s been before.

Aliasing Remotes in the Console

The :remote command in Gremlin Console has a new alias configuration option. This alias option allows specification of a set of key/value alias/binding pairs to apply to the remote. In this way, it becomes possible to refer to a variable on the server as something other than what it is referred to for purpose of the submitted script. For example once a :remote is created, this command:

:remote alias x g

would allow "g" on the server to be referred to as "x".

:> x.E().label().groupCount()

Upgrading for Providers

Important
It is recommended that providers also review all the upgrade instructions specified for users. Many of the changes there may prove important for the provider’s implementation.

All providers should be aware that Jackson is now shaded to gremlin-shaded and could represent breaking change if there was usage of the dependency by way of TinkerPop, a direct dependency to Jackson may be required on the provider’s side.

Graph System Providers

GraphStep Alterations
  • GraphStep is no longer in sideEffect-package, but now in map-package as traversals support mid-traversal V().

  • Traversals now support mid-traversal V()-steps. Graph system providers should ensure that a mid-traversal V() can leverage any suitable index.

See link:https://issues.apache.org/jira/browse/TINKERPOP-762

Decomposition of AbstractTransaction

The AbstractTransaction class has been abstracted into two different classes supporting two different modes of operation: AbstractThreadLocalTransaction and AbstractThreadedTransaction, where the former should be used when supporting ThreadLocal transactions and the latter for threaded transactions. Of course, providers may still choose to build their own implementation on AbstractTransaction itself or simply implement the Transaction interface.

The AbstractTransaction gains the following methods to potentially implement (though default implementations are supplied in AbstractThreadLocalTransaction and AbstractThreadedTransaction):

  • doReadWrite that should execute the read-write consumer.

  • doClose that should execute the close consumer.

Transaction.close() Default Behavior

The default behavior for Transaction.close() is to rollback the transaction and is enforced by tests, which previously asserted the opposite (i.e. commit on close). These tests have been renamed to suite the new semantics:

  • shouldCommitOnCloseByDefault became shouldCommitOnCloseWhenConfigured

  • shouldRollbackOnCloseWhenConfigured became shouldRollbackOnCloseByDefault

If these tests were referenced in an OptOut, then their names should be updated.

Graph Traversal Updates

There were numerous changes to the GraphTraversal API. Nearly all changes are backwards compatible with respective "deprecated" annotations. Please review the respective updates specified in the "Graph System Users" section.

  • GraphStep is no longer in sideEffect package. Now in map package.

  • Make sure mid-traversal GraphStep calls are folding HasContainers in for index-lookups.

  • Think about copying TinkerGraphStepStrategyTest for your implementation so you know folding is happening correctly.

Element Removal

Element.Exceptions.elementAlreadyRemoved has been deprecated and test enforcement for consistency have been removed. Providers are free to deal with deleted elements as they see fit.

VendorOptimizationStrategy Rename

The VendorOptimizationStrategy has been renamed to ProviderOptimizationStrategy. This renaming is consistent with revised terminology for what were formerly referred to as "vendors".

GraphComputer Updates

GraphComputer.configure(String key, Object value) is now a method (with default implementation). This allows the user to specify engine-specific parameters to the underlying OLAP system. These parameters are not intended to be cross engine supported. Moreover, if there are not parameters that can be altered (beyond the standard GraphComputer methods), then the provider’s GraphComputer implementation should simply return and do nothing.

Driver Providers

Aliases Parameter

The "rebindings" argument to the "standard" OpProcessor has been renamed to "aliases". While "rebindings" is still supported it is recommended that the upgrade to "aliases" be made as soon as possible as support will be removed in the future. Gremlin Server will not accept both parameters at the same time - a request must contain either one parameter or the other if either is supplied.

ThreadLocal Transaction Settings

If a driver configures the Transaction.onReadWrite() or Transaction.onClose() settings, note that these settings no longer apply to all future requests. If the settings are changed for a sessionless request they will only apply to that one request. If the settings are changed from an in-session request they will only apply to all future requests made in the scope of that session.

TinkerPop 3.0.0

gremlin hindu

A Gremlin Rāga in 7/16 Time

TinkerPop 3.0.2

Release Date: October 19, 2015

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

BulkLoaderVertexProgram (BLVP)

BulkLoaderVertexProgram now supports arbitrary inputs (i addition to HadoopGraph, which was already supported in version 3.0.1-incubating). It can now also read from any TP3 enabled graph, like TinkerGraph or Neo4jGraph.

TinkerGraph

TinkerGraph can now be configured to support persistence, where TinkerGraph will try to load a graph from a specified location and calls to close() will save the graph data to that location.

Gremlin Driver and Server

There were a number of fixes to gremlin-driver that prevent protocol desynchronization when talking to Gremlin Server.

On the Gremlin Server side, Websocket sub-protocol introduces a new "close" operation to explicitly close sessions. Prior to this change, sessions were closed in a more passive fashion (i.e. session timeout). There were also so bug fixes around the protocol as it pertained to third-party drivers (e.g. python) using JSON for authentication.

Upgrading for Providers

Graph Driver Providers

Gremlin Server close Operation

It is important to note that this feature of the sub-protocol applies to the SessionOpProcessor (i.e. for session-based requests). Prior to this change, there was no way to explicitly close a session. Sessions would get closed by the server after timeout of activity. This new "op" gives drivers the ability to close the session explicitly and as needed.

TinkerPop 3.0.1

Release Date: September 2, 2015

Please see the changelog for a complete list of all the modifications that are part of this release.

Upgrading for Users

Gremlin Server

Gremlin Server now supports a SASL-based (Simple Authentication and Security Layer) authentication model and a default SimpleAuthenticator which implements the PLAIN SASL mechanism (i.e. plain text) to authenticate requests. This gives Gremlin Server some basic security capabilities, especially when combined with its built-in SSL feature.

There have also been changes in how global variable bindings in Gremlin Server are established via initialization scripts. The initialization scripts now allow for a Map of values that can be returned from those scripts. That Map will be used to set global bindings for the server. See this sample script for an example.

Neo4j

Problems related to using :install to get the Neo4j plugin operating in Gremlin Console on Windows have been resolved.

Upgrading for Providers

Graph System Providers

GraphFactoryClass Annotation

Providers can consider the use of the new GraphFactoryClass annotation to specify the factory class that GraphFactory will use to open a new Graph instance. This is an optional feature and will generally help implementations that have an interface extending Graph. If that is the case, then this annotation can be used in the following fashion:

@GraphFactory(MyGraphFactory.class)
public interface MyGraph extends Graph{
}

MyGraphFactory must contain the static open method that is normally expected by GraphFactory.

GraphProvider.Descriptor Annotation

There was a change that affected providers who implemented GraphComputer related tests such as the ProcessComputerSuite. If the provider runs those tests, then edit the GraphProvider implementation for those suites to include the GraphProvider.Descriptor annotation as follows:

@GraphProvider.Descriptor(computer = GiraphGraphComputer.class)
public final class HadoopGiraphGraphProvider extends HadoopGraphProvider {

    public GraphTraversalSource traversal(final Graph graph) {
        return GraphTraversalSource.build().engine(ComputerTraversalEngine.build().computer(GiraphGraphComputer.class)).create(graph);
    }
}

See: TINKERPOP-690 for more information.

Semantics of Transaction.close()

There were some adjustments to the test suite with respect to how Transaction.close() was being validated. For most providers, this will generally mean checking OptOut annotations for test renaming problems. The error that occurs when running the test suite should make it apparent that a test name is incorrect in an OptOut if there are issues there.

See: TINKERPOP-764 for more information.

Graph Driver Providers

Authentication

Gremlin Server now supports SASL-based authentication. By default, Gremlin Server is not configured with authentication turned on and authentication is not required, so existing drivers should still work without any additional change. Drivers should however consider implementing this feature as it is likely that many users will want the security capabilities that it provides.

Appendix

TinkerPop 2.x

This section contains a few notes that reference differences between TinkerPop 2.x and 3.x.

One of the major differences between TinkerPop 2.x and TinkerPop 3.x is that in TinkerPop 3.x, the Java convention of using setters and getters was abandoned in favor of a syntax that is more aligned with the syntax of Gremlin-Groovy in TinkerPop2. Given that Gremlin-Java8 and Gremlin-Groovy are nearly identical due to the inclusion of Java 8 lambdas, a big effort was made to ensure that both languages were as similar as possible.

In addition, TinkerPop2 and below made a sharp distinction between the various TinkerPop projects: Blueprints, Pipes, Gremlin, Frames, Furnace, and Rexster. With TinkerPop 3.x, all of these projects have been merged and are generally known as Gremlin. Blueprints → Gremlin Structure API : PipesGraphTraversal : FramesTraversal : FurnaceGraphComputer and VertexProgram : Rexster → GremlinServer.

GraphML Format

GraphML was a supported format in TinkerPop 2.x, but there were several issues that made it inconsistent with the specification that were corrected for 3.x. As a result, attempting to read a GraphML file generated by 2.x with the 3.x GraphMLReader will result in error. To help with this problem, an XSLT file is provided as a resource in gremlin-core which will transform 2.x GraphML to 3.x GraphML. It can be used as follows:

import javax.xml.parsers.DocumentBuilderFactory;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamSource;
import javax.xml.transform.stream.StreamResult;

InputStream stylesheet = Thread.currentThread().getContextClassLoader().getResourceAsStream("tp2-to-tp3-graphml.xslt");
File datafile = new File('/tmp/tp2-graphml.xml');
File outfile = new File('/tmp/tp3-graphml.xml');

TransformerFactory tFactory = TransformerFactory.newInstance();
StreamSource stylesource = new StreamSource(stylesheet);
Transformer transformer = tFactory.newTransformer(stylesource);

StreamSource source = new StreamSource(datafile);
StreamResult result = new StreamResult(new FileWriter(outfile));
transformer.transform(source, result);

TinkerPop2 Data Migration

data migration For those using TinkerPop 2.x, migrating to TinkerPop 3.x will mean a number of programming changes, but may also require a migration of the data depending on the graph implementation. For example, trying to open TinkerGraph data from TinkerPop 2.x with TinkerPop 3.x code will not work, however opening a TinkerPop2 Neo4jGraph with a TinkerPop 3.x Neo4jGraph should work provided there aren’t Neo4j version compatibility mismatches preventing the read.

If such a situation arises that a particular TinkerPop 2.x Graph can not be read by TinkerPop 3.x, a "legacy" data migration approach exists. The migration involves writing the TinkerPop2 Graph to GraphSON, then reading it to TinkerPop 3.x with the LegacyGraphSONReader (a limited implementation of the GraphReader interface).

The following represents an example migration of the "classic" toy graph. In this example, the "classic" graph is saved to GraphSON using TinkerPop 2.x.

gremlin> Gremlin.version()
==>2.5.z
gremlin> graph = TinkerGraphFactory.createTinkerGraph()
==>tinkergraph[vertices:6 edges:6]
gremlin> GraphSONWriter.outputGraph(graph,'/tmp/tp2.json',GraphSONMode.EXTENDED)
==>null

The above console session uses the gremlin-groovy distribution from TinkerPop2. It is important to generate the tp2.json file using the EXTENDED mode as it will include data types when necessary which will help limit "lossiness" on the TinkerPop 3.x side when imported. Once tp2.json is created, it can then be imported to a TinkerPop 3.x Graph.

gremlin> Gremlin.version()
==>3.5.0-SNAPSHOT
gremlin> graph = TinkerGraph.open()
==>tinkergraph[vertices:0 edges:0]
gremlin> r = LegacyGraphSONReader.build().create()
==>org.apache.tinkerpop.gremlin.structure.io.graphson.LegacyGraphSONReader@64337702
gremlin> r.readGraph(new FileInputStream('/tmp/tp2.json'), graph)
==>null
gremlin> g = graph.traversal()
==>graphtraversalsource[tinkergraph[vertices:6 edges:6], standard]
gremlin> g.E()
==>e[11][4-created->3]
==>e[12][6-created->3]
==>e[7][1-knows->2]
==>e[8][1-knows->4]
==>e[9][1-created->3]
==>e[10][4-created->5]