iframe-proxy

014-code · 2026-07-25T14:42:02Z

Summary

Expose synchronized, idempotent MainEventBusProcessor.start() for CDI and manual wiring.
Start the supplied processor from DefaultRequestHandler construction so manual setups process and persist events.
Keep startup safe when CDI @PostConstruct and explicit wiring both call start().
Cover builder-based manual wiring with a regression test.
Document the CDI constructor and add a manual wiring example using separate agent and event-consumer executors.

Related Issue

This fixes #995.

Verification

mvn -pl server-common -am -Dtest=DefaultRequestHandlerTest#testBuilderStartsManuallyConstructedMainEventBusProcessor -Dsurefire.failIfNoSpecifiedTests=false test — passed (1 test).
mvn -pl server-common -am -DskipTests test-compile — passed.

guofengzh · 2026-07-26T13:02:19Z

Based on the summary in #997, I adjusted the way Spring beans are constructed in ServerConfig, then, the expected response was received.

The change are:

Use the constructor of DefaultRequestHandler to construct an instance of DefaultRequestHandler.
Construct a separate MainEventBusProcessor bean, and then inject it into the DefaultRequestHandler bean.

In other words, the following construct

	@Bean
	public RequestHandler requestHandler(AgentExecutor agentExecutor, TaskStore taskStore, QueueManager queueManager,
	                                     PushNotificationConfigStore pushConfigStore,
										 MainEventBus mainEventBus,
										 PushNotificationSender pushSender,
	                                     @Qualifier("a2aInternal") Executor executor) {
		ExecutorService eventConsumerExecutor = Executors.newFixedThreadPool(3);
		return new DefaultRequestHandler(agentExecutor, taskStore, queueManager, pushConfigStore,
				new MainEventBusProcessor(mainEventBus, taskStore, pushSender, queueManager),
				executor,
				eventConsumerExecutor);
	}

is transformed into

	@Bean
	public MainEventBusProcessor mainEventBusProcessor(MainEventBus mainEventBus,TaskStore taskStore,
													   PushNotificationSender pushSender,
													   QueueManager queueManager) {
		return new MainEventBusProcessor(mainEventBus, taskStore, pushSender, queueManager);
	}
	

	@Bean
	public RequestHandler requestHandler(AgentExecutor agentExecutor, TaskStore taskStore, QueueManager queueManager,
	                                     PushNotificationConfigStore pushConfigStore,
	                                     MainEventBusProcessor mainEventBusProcessor,
	                                     @Qualifier("a2aInternal") Executor executor) {
		return new DefaultRequestHandler(agentExecutor, taskStore, queueManager,
				pushConfigStore, mainEventBusProcessor,
				executor, executor);
	}

Spring Boot recognizes @PostConstruct (and @Inject), so DefaultRequestHandler.initConfig() and MainEventBusProcessor.start() will be executed in this case.

Then, test using the following request:

{
  "jsonrpc": "2.0",
  "id": "6e7bf51a-f364-42d7-a060-343da3cc4f43",
  "method": "SendMessage",
  "params": {
    "message": {
      "messageId": "messageId-1",
      "role": "ROLE_USER",
      "parts": [
        {
          "text": "Can you check systems?"
        }
      ]
    }
  }
}

Response 200 OK

Response Body:

{
  "error": null,
  "id": "6e7bf51a-f364-42d7-a060-343da3cc4f43",
  "jsonrpc": "2.0",
  "result": {
    "role": "ROLE_AGENT",
    "parts": [
      {
        "text": "Hello World",
        "metadata": null
      }
    ],
    "messageId": "d062faba-39e6-4ac6-b891-9e0ba1363a69",
    "contextId": "c2c16e07-dfad-40f1-958c-41d336d4363e",
    "taskId": "d38c2bc5-7491-4920-a290-93582d21a9e0",
    "referenceTaskIds": null,
    "metadata": null,
    "extensions": null
  }
}

That is, a success result was returned.

Hopefully, these new improvements will be helpful to your revisions.

Thanks for what you did.

ehsavoie · 2026-08-05T12:18:33Z

Can you please rebase ? Also an example on how you are using this would be great since it is in SpringBoot runtime

kabir

Thanks @014-code! Overall it looks good, but I think exposing the start() method directly will be simpler.

kabir · 2026-08-05T13:49:00Z

    @SuppressWarnings("NullAway.Init")
    @PostConstruct
-    void start() {
+    synchronized void start() {


I think you can just make this public synchronized

kabir · 2026-08-05T13:49:12Z

     */
    public void ensureStarted() {
-        // Method intentionally empty - just forces proxy resolution
+        start();


Please undo this change

kabir · 2026-08-05T13:49:50Z

        //  I am unsure about the correct scope.
        //  Also reworked to make a Supplier since otherwise the builder gets polluted with wrong tasks
        this.requestContextBuilder = () -> new SimpleRequestContextBuilder(taskStore, false);
+        this.mainEventBusProcessor.ensureStarted();


Just call mainEventBusProcessor.start() if we have to.
But I wonder, since this comes in as a constructor parameter, if you could just not call start() on it before calling the constructor? So this line doesn't seem essential to me.

kabir · 2026-08-05T13:50:39Z

        }
-        eventQueue.enqueueEvent(message);
+        Message messageToSend = message;
+        if (message.taskId() == null || message.contextId() == null) {


Claude thinks:

The null-ID backfill in AgentEmitter (lines 522-528 of the diff) is unrelated to the event bus processor startup fix.
The PR's own test doesn't exercise this path — the test executor calls sendMessage(String), not sendMessage(Message).
This should be a separate PR with its own issue reference.

kabir

@014-code do you plan on looking into this?

Ensure MainEventBusProcessor.ensureStarted() starts manually constructed processors, and call it from DefaultRequestHandler.create(...). This prevents manually wired integrations from leaving events stuck on the main event bus. Add a regression test for the manual wiring path that returns a Message response. This fixes a2aproject#995

Start the main event bus processor from the public request handler constructor and verify the direct manual wiring path.\n\nThis fixes a2aproject#995

kabir · 2026-09-25T13:22:13Z

guofengzh mentioned this pull request Jul 26, 2026

[Help]: Could not find a Task/Message for 84ced8e6-3705-41c6-9158-f2b880463a32 #995

Closed

1 task done

ehsavoie requested a review from kabir August 5, 2026 12:12

kabir reviewed Aug 5, 2026

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kabir requested changes Aug 26, 2026

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014-code and others added 3 commits September 25, 2026 13:47

fix(server): cover direct request handler wiring

e2d6011

Start the main event bus processor from the public request handler constructor and verify the direct manual wiring path.\n\nThis fixes a2aproject#995

fix(server): expose event processor startup

4b6eac7

kabir force-pushed the fix/995-main-event-bus-processor-startup branch from 6a59823 to 4b6eac7 Compare September 25, 2026 12:50

fix(server): cover builder-based manual processor startup

088bc77

ehsavoie merged commit 7e73cab into a2aproject:main Sep 25, 2026
17 checks passed

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fix(server): start event bus processor for manual wiring - #997

fix(server): start event bus processor for manual wiring#997
ehsavoie merged 4 commits into
a2aproject:mainfrom
014-code:fix/995-main-event-bus-processor-startup

014-code commented Jul 25, 2026 •

edited by kabir

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Summary

Related Issue

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014-code commented Jul 25, 2026 •

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