将所有事件从CommandGateway路由到单个事件处理程序

Question

我正在使用AxonFramework实现JGroups，我指的是this链接。我在代码中进行了一些更改，并在没有Docker的情况下运行项目。以下是我的代码 -

主要类别

public class ClusterRunner {

   public static void main(String[] args) {

      Thread t1 = new Thread(new PrimaryNode());
      Thread t2 = new Thread(new SecondaryNode());

      t1.start();
      t2.start();
   }
}

主节点 -

import org.axonframework.commandhandling.AggregateAnnotationCommandHandler;
import org.axonframework.commandhandling.CommandBus;
import org.axonframework.commandhandling.SimpleCommandBus;
import org.axonframework.commandhandling.distributed.AnnotationRoutingStrategy;
import org.axonframework.commandhandling.distributed.DistributedCommandBus;
import org.axonframework.commandhandling.distributed.commandfilter.AcceptAll;
import org.axonframework.commandhandling.gateway.CommandGateway;
import org.axonframework.commandhandling.gateway.DefaultCommandGateway;
import org.axonframework.commandhandling.model.Repository;
import org.axonframework.eventsourcing.EventSourcingRepository;
import org.axonframework.eventsourcing.eventstore.EmbeddedEventStore;
import org.axonframework.eventsourcing.eventstore.EventStore;
import org.axonframework.eventsourcing.eventstore.inmemory.InMemoryEventStorageEngine;
import org.axonframework.jgroups.commandhandling.JGroupsConnector;
import org.axonframework.serialization.xml.XStreamSerializer;
import org.jgroups.JChannel;

public class PrimaryNode implements Runnable {

    private JGroupsConnector connector;

    private CommandGateway commandGateway;

    private EventStore eventStore;

    private CommandBus commandBus;

    public PrimaryNode() {

        eventStore = new EmbeddedEventStore(new InMemoryEventStorageEngine());

        try {

            commandBus = configureDistributedCommandBus();

        } catch (Exception e) {

            e.printStackTrace();
        }

        Repository<Item> repository = new EventSourcingRepository<>(Item.class, eventStore);

        new AggregateAnnotationCommandHandler<>(Item.class, repository).subscribe(commandBus);

        commandGateway = new DefaultCommandGateway(commandBus);
    }

    public void run() {

        for (int a = 0; a < 5; a++) {

            System.out.println("Primary Node Created item " + a + " id: " + System.currentTimeMillis());
            commandGateway.sendAndWait(new CreateItem(Long.toString(a), Long.toString(System.currentTimeMillis())));
        }
    }

    private CommandBus configureDistributedCommandBus() throws Exception {

        CommandBus commandBus = new SimpleCommandBus();

        JChannel channel = new JChannel(getClass().getClassLoader().getResourceAsStream("tcp.xml"));

        connector = new JGroupsConnector(commandBus, channel, "axon-jgroups-demo", new XStreamSerializer(),
            new AnnotationRoutingStrategy());
        connector.updateMembership(100, AcceptAll.INSTANCE);

        connector.connect();
        connector.awaitJoined();

        return new DistributedCommandBus(connector, connector);
    }
}

第二节点 -

import org.axonframework.commandhandling.AggregateAnnotationCommandHandler;
import org.axonframework.commandhandling.CommandBus;
import org.axonframework.commandhandling.SimpleCommandBus;
import org.axonframework.commandhandling.distributed.AnnotationRoutingStrategy;
import org.axonframework.commandhandling.distributed.DistributedCommandBus;
import org.axonframework.commandhandling.distributed.commandfilter.AcceptAll;
import org.axonframework.commandhandling.gateway.CommandGateway;
import org.axonframework.commandhandling.gateway.DefaultCommandGateway;
import org.axonframework.commandhandling.model.Repository;
import org.axonframework.eventhandling.EventListener;
import org.axonframework.eventhandling.SimpleEventHandlerInvoker;
import org.axonframework.eventhandling.SubscribingEventProcessor;
import org.axonframework.eventsourcing.EventSourcingRepository;
import org.axonframework.eventsourcing.eventstore.EmbeddedEventStore;
import org.axonframework.eventsourcing.eventstore.EventStore;
import org.axonframework.eventsourcing.eventstore.inmemory.InMemoryEventStorageEngine;
import org.axonframework.jgroups.commandhandling.JGroupsConnector;
import org.axonframework.serialization.xml.XStreamSerializer;
import org.jgroups.JChannel;

public class SecondaryNode implements Runnable {

    private JGroupsConnector connector;

    private EventStore eventStore;

    public SecondaryNode() {

        eventStore = new EmbeddedEventStore(new InMemoryEventStorageEngine());

        CommandBus commandBus = null;

        try {
            commandBus = configureDistributedCommandBus();
        } catch (Exception e) {
            e.printStackTrace();
        }

        Repository<Item> repository = new EventSourcingRepository<>(Item.class, eventStore);

        new AggregateAnnotationCommandHandler<>(Item.class, repository).subscribe(commandBus);

        @SuppressWarnings("unused")
        CommandGateway commandGateway = new DefaultCommandGateway(commandBus);
    }

    public void run() {

        new SubscribingEventProcessor("processor", new SimpleEventHandlerInvoker((EventListener) event -> {

            System.out.println("Secondary Node -- " + event.getPayload());
        }), eventStore).start();
    }

    private CommandBus configureDistributedCommandBus() throws Exception {

        CommandBus commandBus = new SimpleCommandBus();

        JChannel channel = new JChannel(getClass().getClassLoader().getResourceAsStream("tcp_test.xml"));

        connector = new JGroupsConnector(commandBus, channel, "axon-jgroups-demo", new XStreamSerializer(),
                new AnnotationRoutingStrategy());
        connector.updateMembership(100, AcceptAll.INSTANCE);

        connector.connect();
        connector.awaitJoined();

        return new DistributedCommandBus(connector, connector);
    }
}

项目

import org.axonframework.commandhandling.CommandHandler;
import org.axonframework.commandhandling.TargetAggregateIdentifier;
import org.axonframework.commandhandling.model.AggregateIdentifier;
import org.axonframework.eventhandling.EventHandler;

import static org.axonframework.commandhandling.model.AggregateLifecycle.apply;

class CreateItem {

    @TargetAggregateIdentifier
    private final String itemId;
    private final String name;

    public CreateItem(String itemId, String naam) {
        this.itemId = itemId;
        this.name = naam;
    }

    public String getItemId() {
        return itemId;
    }

    public String getName() {
        return name;
    }
}

class ItemCreated {
    private final String itemId;
    private final String name;

    public ItemCreated(String itemId, String naam) {
        this.itemId = itemId;
        this.name = naam;
    }

    public String getItemId() {
        return itemId;
    }

    public String getName() {
        return name;
    }

    @Override
    public String toString() {

        return itemId + "    " + name;
    }
}

class Item {
    @AggregateIdentifier
    private String itemId;
    private String name;

    public Item() {

    }

    @CommandHandler
    public Item(CreateItem createItem) {
        apply(new ItemCreated(createItem.getItemId(), createItem.getName()));
    }

    @EventHandler
    public void itemCreated(ItemCreated itemCreated) {
        itemId = itemCreated.getItemId();
        name = itemCreated.getName();
    }
}

现在我的问题是，当我运行主类时，主节点产生5个事件但是辅助节点没有获得所有事件。它可能会获得2或3或4个事件但不是全部。我希望将所有事件传递到辅助节点。我是AxonFramework和JGroups的新手。请帮我理解这里的问题。

Answer 1

默认情况下，Axon会将每个事件处理程序订阅到事件总线（在您的情况下为EmbeddedEventStore）。这意味着当该特定本地实例发布Event时，将调用该处理程序。并且在处理命令时发布该事件。基本上，在处理命令的节点上调用事件处理程序。

或者，您可以将事件处理程序配置为以“跟踪”模式运行。在这种情况下，他们将打开与事件存储的连接。在这种情况下，根据确切的配置，每个节点都可以获取自己的事件副本，无论它在何处发布。

Answer 2

所以在尝试了一切后，我决定尝试路由策略。我决定使用AbstractRoutingStrategy，它基本上有助于决策制定没有决定性目的地的命令消息。以下是JGroup的主节点（发送方）中的工作代码。将PrimaryDode类中的configureDistributedCommandBus（）方法修改为 -

private CommandBus configureDistributedCommandBus() throws Exception {

    CommandBus commandBus = new SimpleCommandBus();

    channel = new JChannel(getClass().getClassLoader().getResourceAsStream("tcp.xml"));

    RoutingStrategy rs = new AbstractRoutingStrategy(UnresolvedRoutingKeyPolicy.STATIC_KEY) {

        @Override
        protected String doResolveRoutingKey(CommandMessage<?> cmdMsg) {

            View view = channel.getView();

            if (view.getMembers().size() == 2) {

                return "secondary";

            } else if (view.getMembers().size() == 1) {

            }

            return cmdMsg.getIdentifier();
        }
    };

    connector = new JGroupsConnector(commandBus, channel, "axon-jgroups-demo", new XStreamSerializer(), rs);
    connector.updateMembership(100, AcceptAll.INSTANCE);

    connector.connect();
    connector.awaitJoined();

    return new DistributedCommandBus(connector, connector);
}

由于我正在使用JGroups，我可以获得集群的视图，即有多少个节点。在此基础上，我将决定命令消息路由。