gremlin - 具有远程 JanusGraph 的突变监听器事件策略抛出序列化异常

Question

我想监听远程 JanusGraph 上的突变，但我无法找出使其工作的正确设置。

JanusGraph 堆栈:
JanusGraph docker 镜像 **0.5.2(使用 Apache TinkerPop Gremlin 3.4.6)和 cql-es 配置
Cassandra docker 镜像 3.11.6
ElasticSearch docker 镜像 7.3.1
gremlin-server-cql-es.yaml 的序列化器部分已更新为以下行:

- { className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV3d0, config: { ioRegistries: [org.janusgraph.graphdb.tinkerpop.JanusGraphIoRegistry, org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerIoRegistryV3d0] }}
- { className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV3d0, config: { serializeResultToString: true }}

Java 客户端堆栈: 基于pluradj/janusgraph-java-example
Java8
janusgraph-core 0.5.2
gremlin-driver 3.4.6
remote-objects.yaml 如下所示:

hosts: [127.0.0.1]
port: 8182
serializer: {
  className: org.apache.tinkerpop.gremlin.driver.ser.GryoMessageSerializerV3d0,
  config: {
    ioRegistries: [org.janusgraph.graphdb.tinkerpop.JanusGraphIoRegistry, org.apache.tinkerpop.gremlin.tinkergraph.structure.TinkerIoRegistryV3d0]
  }
}

完整代码(没有ConsoleMutationListener)如下所示:

public static void main(String[] args) {

    MutationListener mutationListener = new ConsoleMutationListener("Test");
    EventStrategy eventStrategy = EventStrategy.build().addListener(mutationListener).create();

    try (GraphTraversalSource g = AnonymousTraversalSource.traversal()
        .withRemote("conf/remote-graph.properties")
        .withStrategies(eventStrategy)) {

        g.addV("person").property("name", "Test").next();
    } catch (Exception e) {
        e.printStackTrace();
    }
}

ConsoleMutationListener 是 TinkerPop 示例 ConsoleMutationListener 的副本使用修改后的构造函数来接受图形名称而不是完整图形，因为 toString() 是唯一使用的方法。

堆栈跟踪:

io.netty.handler.codec.EncoderException: org.apache.tinkerpop.gremlin.driver.exception.ResponseException: An error occurred during serialization of this request [RequestMessage{, requestId=9436b08c-7e31-4fc0-b480-40904055f491, op='bytecode', processor='traversal', args={gremlin=[[withStrategies(EventStrategy)], [addV(person), property(name, Test)]], aliases={g=g}}}] - it could not be sent to the server - Reason: org.apache.tinkerpop.gremlin.driver.ser.SerializationException: java.lang.IllegalArgumentException: Class is not registered: org.apache.tinkerpop.gremlin.process.traversal.strategy.decoration.EventStrategy
Note: To register this class use: kryo.register(org.apache.tinkerpop.gremlin.process.traversal.strategy.decoration.EventStrategy.class);
    at io.netty.handler.codec.MessageToMessageEncoder.write(MessageToMessageEncoder.java:107)
    at io.netty.channel.AbstractChannelHandlerContext.invokeWrite0(AbstractChannelHandlerContext.java:716)
    at io.netty.channel.AbstractChannelHandlerContext.invokeWrite(AbstractChannelHandlerContext.java:708)
    at io.netty.channel.AbstractChannelHandlerContext.access$1700(AbstractChannelHandlerContext.java:56)
    at io.netty.channel.AbstractChannelHandlerContext$AbstractWriteTask.write(AbstractChannelHandlerContext.java:1102)
    at io.netty.channel.AbstractChannelHandlerContext$WriteAndFlushTask.write(AbstractChannelHandlerContext.java:1149)
    at io.netty.channel.AbstractChannelHandlerContext$AbstractWriteTask.run(AbstractChannelHandlerContext.java:1073)
    at io.netty.util.concurrent.AbstractEventExecutor.safeExecute(AbstractEventExecutor.java:163)
    at io.netty.util.concurrent.SingleThreadEventExecutor.runAllTasks(SingleThreadEventExecutor.java:510)
    at io.netty.channel.nio.NioEventLoop.run(NioEventLoop.java:518)
    at io.netty.util.concurrent.SingleThreadEventExecutor$6.run(SingleThreadEventExecutor.java:1044)
    at io.netty.util.internal.ThreadExecutorMap$2.run(ThreadExecutorMap.java:74)
    at java.lang.Thread.run(Thread.java:748)
Caused by: org.apache.tinkerpop.gremlin.driver.exception.ResponseException: An error occurred during serialization of this request [RequestMessage{, requestId=9436b08c-7e31-4fc0-b480-40904055f491, op='bytecode', processor='traversal', args={gremlin=[[withStrategies(EventStrategy)], [addV(person), property(name, Test)]], aliases={g=g}}}] - it could not be sent to the server - Reason: org.apache.tinkerpop.gremlin.driver.ser.SerializationException: java.lang.IllegalArgumentException: Class is not registered: org.apache.tinkerpop.gremlin.process.traversal.strategy.decoration.EventStrategy
Note: To register this class use: kryo.register(org.apache.tinkerpop.gremlin.process.traversal.strategy.decoration.EventStrategy.class);
    at org.apache.tinkerpop.gremlin.driver.handler.WebSocketGremlinRequestEncoder.encode(WebSocketGremlinRequestEncoder.java:60)
    at org.apache.tinkerpop.gremlin.driver.handler.WebSocketGremlinRequestEncoder.encode(WebSocketGremlinRequestEncoder.java:38)
    at io.netty.handler.codec.MessageToMessageEncoder.write(MessageToMessageEncoder.java:89)
    ... 12 more

如果我删除 withStrategies(eventStrategy)，顶点将添加到图表中，并且我也可以正常查询图表。但是，我无法使用 EventStrategy 配置 GraphTraversalSource。

Q1:我的想法是，具有已定义事件策略的消息无法使用 GryoMessageSerializerV3d0 进行序列化，或者应该以某种方式在服务器端注册突变监听器/事件策略，但我找不到任何关于如何做到这一点的引用。有此类配置的示例吗？

问题2:我做错了什么？是否可以将 TinkerPop 的 EventStrategy 与 JanusGraph 结合使用？

Q3:是否有其他方法来监听远程 JanusGraph 突变？

将序列化器更改为 GraphSONMessageSerializerV3d0 给出:

java.util.concurrent.CompletionException: org.apache.tinkerpop.gremlin.driver.exception.ResponseException: EventStrategy does can only be constructed with instance() or create(Configuration)
    at java.util.concurrent.CompletableFuture.reportJoin(CompletableFuture.java:375)
    at java.util.concurrent.CompletableFuture.join(CompletableFuture.java:1947)
...
Caused by: org.apache.tinkerpop.gremlin.driver.exception.ResponseException: EventStrategy does can only be constructed with instance() or create(Configuration)

将序列化器更改为 GraphBinaryMessageSerializerV1 会给出:

java.util.concurrent.CompletionException: io.netty.handler.codec.DecoderException: org.apache.tinkerpop.gremlin.driver.ser.SerializationException: The most significant bit should be set according to the format
    at java.util.concurrent.CompletableFuture.reportJoin(CompletableFuture.java:375)
    at java.util.concurrent.CompletableFuture.join(CompletableFuture.java:1947)
...
Caused by: io.netty.handler.codec.DecoderException: org.apache.tinkerpop.gremlin.driver.ser.SerializationException: The most significant bit should be set according to the format

Answer 1

Q1: What I'm thinking is that message with defined Event Strategy cannot be serialized with GryoMessageSerializerV3d0 or Mutation Listener/Event Strategy should somehow be registered on the server side, but I can't find any references on how to do that.

这是正确的。 EventStrategy 无法跨远程连接工作。

Q2: What am I doing wrong? Is it even possible to use TinkerPop's EventStrategy with JanusGraph?

可以将其与 JanusGraph 一起使用，但只能在嵌入模式下使用，因为 MutationListener 实现不知道如何将事件发送回客户端。驱动程序可能需要一些重大更改来引入支持机制，因此这是一个不小的更改。如果解决了这一点，那么仍然存在序列化问题需要为提供自定义 MutationListeners 的用户解决(尽管也许这只是不允许的)。

Q3: Is there any other approach to listen to remote JanusGraph mutations?

这里的关键词是“远程”，我认为目前不存在任何允许这样做的东西。您需要构建自己的某种类型。一种方法可能是在服务器上使用 EventStrategy 配置“g”，然后添加一个 MutationListener，将这些事件发送到您可以远程使用的单独队列。您也可以考虑查看JanusGraph Bus并设计一个类似的方案。