Serializing a JanusGraph subgraph in Gremlin-Java

[John Ripley]

I am connecting to a remote JanusGraph 0.20 instance from Java.  My client is using Tinkerpop 3.2.6.  I can do all the standard stuff, return vertices, edges, etc.

When I try to build a 2 generation subgraph in starting from a known seed

   Object o = g.V().has("id", 1).repeat(__.bothE().subgraph("subGraph").outV()).times(2).cap("subGraph").next();

I get the following exception:

org.apache.tinkerpop.gremlin.driver.exception.ResponseException: Error during serialization: Class is not registered: org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerGraph

Note: To register this class use: kryo.register(org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerGraph.class);

at org.apache.tinkerpop.gremlin.driver.Handler$GremlinResponseHandler.channelRead0(Handler.java:246) ~[gremlin-driver-3.3.1.jar:3.3.1]

        ...

This same line works fine in the gremlin console.  

gremlin> sg = g.V().has('id', 1).repeat(bothE().subgraph('subGraph').bothV()).times(3).cap('subGraph').next()

==>tinkergraph[vertices:4 edges:4]

I am using the out of the box JanusGraph 0.20 gremlin-server.yaml and remote-objects.yaml

[Stephen Mallette]

Seems like you driver isn't configured to use the TinkerIoRegistry which will allow it to deserialize TinkerGraph instances:

https://github.com/apache/tinkerpop/blob/master/gremlin-console/conf/remote-objects.yaml#L36

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[John Ripley]

I add the serializer to my client side remote-objects.yaml and got a little further.

hosts: [127.0.0.1]

port: 8182

serializer: {

    className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV1d0,

    config: {

        ioRegistries: [org.janusgraph.graphdb.tinkerpop.JanusGraphIoRegistry]

    },

    className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV3d0,

    config: { ioRegistries: [org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerIoRegistryV3d0] 

    }

}

Do I need to pair this with a gremin-server.yaml entry?  This is the Janus 0.2.0 version that I am using

host: 0.0.0.0

port: 8182

scriptEvaluationTimeout: 30000

channelizer: org.apache.tinkerpop.gremlin.server.channel.WebSocketChannelizer

graphs: {

  graph: conf/gremlin-server/janusgraph-cassandra-es-server.properties

}

plugins:

  - janusgraph.imports

scriptEngines: {

  gremlin-groovy: {

    imports: [java.lang.Math],

    staticImports: [java.lang.Math.PI],

    scripts: [scripts/empty-sample.groovy]}}

serializers:

  - { className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV1d0, config: { ioRegistries: [org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerIoRegistry] }}   

  - { className: org.apache.tinkerpop.gremlin.driver.ser.GryoLiteMessageSerializerV1d0, config: {ioRegistries: [org.janusgraph.graphdb.tinkerpop.JanusGraphIoRegistry] }}

  - { className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV1d0, config: { serializeResultToString: true }}

  - { className: org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerGremlinV1d0, config: { ioRegistries: [org.janusgraph.graphdb.tinkerpop.JanusGraphIoRegistryV1d0] }}

  - { className: org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerGremlinV2d0, config: { ioRegistries: [org.janusgraph.graphdb.tinkerpop.JanusGraphIoRegistry] }}

  - { className: org.apache.tinkerpop.gremlin.driver.ser.GraphSONMessageSerializerV1d0, config: { ioRegistries: [org.janusgraph.graphdb.tinkerpop.JanusGraphIoRegistryV1d0] }}

processors:

  - { className: org.apache.tinkerpop.gremlin.server.op.session.SessionOpProcessor, config: { sessionTimeout: 28800000 }}

  - { className: org.apache.tinkerpop.gremlin.server.op.traversal.TraversalOpProcessor, config: { cacheExpirationTime: 600000, cacheMaxSize: 1000 }}

metrics: {

  consoleReporter: {enabled: true, interval: 180000},

  csvReporter: {enabled: true, interval: 180000, fileName: /tmp/gremlin-server-metrics.csv},

  jmxReporter: {enabled: true},

  slf4jReporter: {enabled: true, interval: 180000},

  gangliaReporter: {enabled: false, interval: 180000, addressingMode: MULTICAST},

  graphiteReporter: {enabled: false, interval: 180000}}

maxInitialLineLength: 4096

maxHeaderSize: 8192

maxChunkSize: 8192

maxContentLength: 65536

maxAccumulationBufferComponents: 1024

resultIterationBatchSize: 64

writeBufferLowWaterMark: 32768

writeBufferHighWaterMark: 65536

Also, it seems that JanusGraph is on tp 3.2.6 and my client needs to import tp 3.3.x for it to correctly find your above mentioned serializer.  Will JanusGraph need to upgrade to tp 3.3.x for the server side serializer to work?

[John Ripley]

I was able to get it to work by including both JanusGraph and TinkerPop IoRegistries on both server and client

Tinkerpop 3.2.6 on (Janus 0.2.0) gremlin server and client

gremlin-server.yaml

...

serializers:

  - { className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV1d0, config: { ioRegistries: [org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerIoRegistry,org.janusgraph.graphdb.tinkerpop.JanusGraphIoRegistry] }}

...

remote-objects.yaml

hosts: [127.0.0.1]

port: 8182

serializer: {

    className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV1d0,

    config: {

        ioRegistries: [org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerIoRegistry,org.janusgraph.graphdb.tinkerpop.JanusGraphIoRegistry]

    }   

}

If I include only TinkIoRegistry, it complains about not being able to handle certain JanusGraph classes.  If I just include JanusGraphIoRegistry, it complains about not being able to handle certain Tinkerpop classes.

Thanks for your help, Stephen

On Thursday, April 5, 2018 at 5:01:12 PM UTC-5, John Ripley wrote:

[Fred Eisele]

I am getting the same errors you got but the fix is not doing it for me.

```yaml
hosts: [localhost]
port: 8182
serializer:
   className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV3d0
   config:
     ioRegistries:
       - org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerIoRegistryV3d0
       - org.janusgraph.graphdb.tinkerpop.JanusGraphIoRegistry

```

```text

Exception in thread "main" java.util.concurrent.CompletionException:

org.apache.tinkerpop.gremlin.driver.exception.ResponseException:

Error during serialization:

Class is not registered: org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerGraph
Note: To register this class use:

kryo.register(org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerGraph.class);
    at java.base/java.util.concurrent.CompletableFuture.reportJoin(CompletableFuture.java:412)

```

Meanwhile the groovy-gremlin-client works fine and it makes no mention of the TinkerIoRegistryV3d0.