Introduce quarkus-signals experimental extension by mkouba · Pull Request #53788 · quarkusio/quarkus

mkouba · 2026-04-24T08:21:21Z

that allows application components to interact in a loosely coupled fashion, by emitting and receiving signals
see also WG Proposal - Unified Events: Working Group Proposal - Unified Event Bus #53202
this commit includes the extension itself, the docs and integration tests

Definition of Done (taken from the WG proposal)

Note

The extension does not even require the Vert.x dependency unless the NON_BLOCKING execution model is used by a receiver.

Missing pieces

Context propagation

The plan is to suppot propagation of security identity and OTel tracing stuff. It should be implemented with the io.quarkus.signals.spi.ReceiverInterceptor and io.quarkus.signals.spi.SignalMetadataEnricher SPI in relevant extensions. However, we believe that a receiver notification should always run on a new CDI request context -- a new CDI request is activated for each receiver notification. There is no plan to propagate some other contexts.

Relationship between the new API, CDI events, and in-memory Reactive Messaging

So far the documentation clearly express that receiver resolution is inspired by CDI, emission modes are inspired by the Vert.x EventBus, and the execution model is following Quarkus conventions.

Migration guide from `@ConsumeEvent` and Vert.x event bus

This is out of scope while in an experimental phase.

Unfinished parts

The extension should be feature-complete. However, there are parts where we need some feedback. More specifically, the following topics are not considered a "solved problem".

Signal emission methods

Currently, common-case methods have the short names, and the Uni suffix marks the reactive variants. For example, void Signal#publish(T) and Uni<Void> Signal#publishUni(T) (note that Async suffix makes no sense because signals are always send asynchronously). It's not perfect but we want to keep the reactive variants and we think that short names for reactive variants are not convenient for users, i.e. Uni<Void> Signal#publish(T) and void Signal#publishAndForget(T).

Resolution - the only difference from the CDI specification

In CDI, an observer method that declares no qualifiers receives an empty set of observed qualifiers, and as a result, is notified of any event that matches the observed type, i.e. void onAnyFoo(@Observes Foo) {} is notified even for @Inject @SomeQualified Event<Foo>. In Signals, a receiver which declares no qualifier has exactly one qualifier -- @Default, as a result, you need to use something like void onAnyFoo(@Receives @Any Foo) {} to be notified even for @Inject @SomeQualified Signal<Foo>. My personal opinion is that the Signals approach is more aligned with CDI injection rules (@Inject Foo also results in @Inject @Default Foo) and also reads more naturally ("notify on any Foo"). @manovotn correctly points out that it is not compatible with CDI and users might get confused. It's important to note that Signals have a completely different execution model anyway (compared to CDI). So I personally think that users will be more confused by other differences, e.g. where are transactional observers, where is ordering, why is the receiver executed on a different request context, etc. And that's fine because Signal != CDI events.

API history and evolution

The original POC can be found in this repository: https://github.com/mkouba/quarkus-signals

github-actions · 2026-04-24T08:56:05Z

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- that allows application components to interact in a loosely coupled fashion, by emitting and receiving _signals_ - see also WG Proposal - Unified Events: quarkusio#53202 - this commit includes the extension itself, the docs and integration tests

quarkus-bot · 2026-04-24T18:58:09Z

Status for workflow `Quarkus Documentation CI`

This is the status report for running Quarkus Documentation CI on commit 6ee37fb.

✅ The latest workflow run for the pull request has completed successfully.

It should be safe to merge provided you have a look at the other checks in the summary.

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quarkus-bot · 2026-04-25T00:06:54Z

Status for workflow `Quarkus CI`

This is the status report for running Quarkus CI on commit 6ee37fb.

Failing Jobs

Status	Name	Step	Failures	Logs	Raw logs	Build scan
✔️	JVM Tests - JDK 17			Logs	Raw logs	🔍
✔️	JVM Tests - JDK 21			Logs	Raw logs	🔍
✔️	JVM Tests - JDK 25			Logs	Raw logs	🔍
✔️	JVM Tests - JDK 25 Semeru			Logs	Raw logs	🔍
❌	JVM Tests - JDK 17 Windows	`Cache Develocity local cache`	⚠️ Check →	Logs	Raw logs	🚧
✔️	Kubernetes Tests - JDK 25			Logs	Raw logs	🔍
❌	Kubernetes Tests - JDK 25 Semeru	`Build`	Failures	Logs	Raw logs	🔍
✔️	Kubernetes Tests - JDK 17 Windows			Logs	Raw logs	🔍
❌	Native Tests - Misc1	`Build`	⚠️ Check →	Logs	Raw logs	🚧

You can consult the Develocity build scans.

Failures

⚙️ Kubernetes Tests - JDK 25 Semeru #

- Failing: integration-tests/kubernetes/maven-invoker-way

📦 integration-tests/kubernetes/maven-invoker-way

❌ Failed to execute goal org.apache.maven.plugins:maven-invoker-plugin:3.9.1:run (integration-tests) on project quarkus-integration-test-kubernetes-invoker: 1 build failed. See console output above for details.

Flaky tests - Develocity

⚙️ JVM Tests - JDK 25

📦 extensions/vertx-http/deployment

❌ io.quarkus.vertx.http.filters.GracefulShutdownFilterTest.test - History

Timeout waiting for response - java.lang.RuntimeException

Details

java.lang.RuntimeException: Timeout waiting for response
	at io.quarkus.vertx.http.filters.GracefulShutdownFilterTest.testWithVertxHttpClientAndHttp2AfterShutdown(GracefulShutdownFilterTest.java:85)
	at io.quarkus.vertx.http.filters.GracefulShutdownFilterTest.test(GracefulShutdownFilterTest.java:59)

⚙️ JVM Tests - JDK 25 Semeru

📦 extensions/quartz/deployment

❌ io.quarkus.quartz.test.PausedSchedulerTest.testSchedulerPauseResume - History

expected: <false> but was: <true> - org.opentest4j.AssertionFailedError

Details

org.opentest4j.AssertionFailedError: expected: <false> but was: <true>
	at org.junit.jupiter.api.AssertionFailureBuilder.build(AssertionFailureBuilder.java:158)
	at org.junit.jupiter.api.AssertionFailureBuilder.buildAndThrow(AssertionFailureBuilder.java:139)
	at org.junit.jupiter.api.AssertFalse.failNotFalse(AssertFalse.java:69)
	at org.junit.jupiter.api.AssertFalse.assertFalse(AssertFalse.java:41)
	at org.junit.jupiter.api.AssertFalse.assertFalse(AssertFalse.java:35)
	at org.junit.jupiter.api.Assertions.assertFalse(Assertions.java:246)
	at io.quarkus.quartz.test.PausedSchedulerTest.testSchedulerPauseResume(PausedSchedulerTest.java:47)

📦 extensions/vertx-http/deployment

❌ io.quarkus.vertx.http.filters.GracefulShutdownFilterTest.test - History

Timeout waiting for response - java.lang.RuntimeException

Details

java.lang.RuntimeException: Timeout waiting for response
	at io.quarkus.vertx.http.filters.GracefulShutdownFilterTest.testWithVertxHttpClientAndHttp2AfterShutdown(GracefulShutdownFilterTest.java:85)
	at io.quarkus.vertx.http.filters.GracefulShutdownFilterTest.test(GracefulShutdownFilterTest.java:59)

⚙️ Native Tests - Messaging1

📦 integration-tests/reactive-messaging-kafka

❌ io.quarkus.it.kafka.KafkaConnectorIT.testPets - History

Assertion condition defined as a Lambda expression in io.quarkus.it.kafka.KafkaConnectorTest expected: <6> but was: <3> within 10 seconds. - org.awaitility.core.ConditionTimeoutException

Details

org.awaitility.core.ConditionTimeoutException: Assertion condition defined as a Lambda expression in io.quarkus.it.kafka.KafkaConnectorTest expected: <6> but was: <3> within 10 seconds.
	at org.awaitility.core.ConditionAwaiter.await(ConditionAwaiter.java:167)
	at org.awaitility.core.AssertionCondition.await(AssertionCondition.java:119)
	at org.awaitility.core.AssertionCondition.await(AssertionCondition.java:31)
	at org.awaitility.core.ConditionFactory.until(ConditionFactory.java:1160)
	at org.awaitility.core.ConditionFactory.untilAsserted(ConditionFactory.java:790)
	at io.quarkus.it.kafka.KafkaConnectorTest.testPets(KafkaConnectorTest.java:62)
	at java.base/java.lang.reflect.Method.invoke(Method.java:565)

⚙️ JVM Integration Tests - JDK 17

📦 integration-tests/reactive-messaging-kafka

❌ io.quarkus.it.kafka.KafkaConnectorTest.testPets - History

Assertion condition defined as a Lambda expression in io.quarkus.it.kafka.KafkaConnectorTest expected: <4> but was: <3> within 10 seconds. - org.awaitility.core.ConditionTimeoutException

Details

org.awaitility.core.ConditionTimeoutException: Assertion condition defined as a Lambda expression in io.quarkus.it.kafka.KafkaConnectorTest expected: <4> but was: <3> within 10 seconds.
	at org.awaitility.core.ConditionAwaiter.await(ConditionAwaiter.java:167)
	at org.awaitility.core.AssertionCondition.await(AssertionCondition.java:119)
	at org.awaitility.core.AssertionCondition.await(AssertionCondition.java:31)
	at org.awaitility.core.ConditionFactory.until(ConditionFactory.java:1160)
	at org.awaitility.core.ConditionFactory.untilAsserted(ConditionFactory.java:790)
	at io.quarkus.it.kafka.KafkaConnectorTest.testPets(KafkaConnectorTest.java:62)
Caused by: org.opentest4j.AssertionFailedError: expected: <4> but was: <3>

Assertion condition defined as a Lambda expression in io.quarkus.it.kafka.KafkaConnectorTest expected: <6> but was: <3> within 10 seconds. - org.awaitility.core.ConditionTimeoutException

Details

org.awaitility.core.ConditionTimeoutException: Assertion condition defined as a Lambda expression in io.quarkus.it.kafka.KafkaConnectorTest expected: <6> but was: <3> within 10 seconds.
	at org.awaitility.core.ConditionAwaiter.await(ConditionAwaiter.java:167)
	at org.awaitility.core.AssertionCondition.await(AssertionCondition.java:119)
	at org.awaitility.core.AssertionCondition.await(AssertionCondition.java:31)
	at org.awaitility.core.ConditionFactory.until(ConditionFactory.java:1160)
	at org.awaitility.core.ConditionFactory.untilAsserted(ConditionFactory.java:790)
	at io.quarkus.it.kafka.KafkaConnectorTest.testPets(KafkaConnectorTest.java:62)
Caused by: org.opentest4j.AssertionFailedError: expected: <6> but was: <3>

⚙️ JVM Integration Tests - JDK 25

📦 integration-tests/reactive-messaging-kafka

❌ io.quarkus.it.kafka.KafkaConnectorTest.testDataForKeyed - History

Assertion condition defined as a Lambda expression in io.quarkus.it.kafka.KafkaConnectorTest expected: <3> but was: <4> within 10 seconds. - org.awaitility.core.ConditionTimeoutException

Details

org.awaitility.core.ConditionTimeoutException: Assertion condition defined as a Lambda expression in io.quarkus.it.kafka.KafkaConnectorTest expected: <3> but was: <4> within 10 seconds.
	at org.awaitility.core.ConditionAwaiter.await(ConditionAwaiter.java:167)
	at org.awaitility.core.AssertionCondition.await(AssertionCondition.java:119)
	at org.awaitility.core.AssertionCondition.await(AssertionCondition.java:31)
	at org.awaitility.core.ConditionFactory.until(ConditionFactory.java:1160)
	at org.awaitility.core.ConditionFactory.untilAsserted(ConditionFactory.java:790)
	at io.quarkus.it.kafka.KafkaConnectorTest.testDataForKeyed(KafkaConnectorTest.java:96)
Caused by: org.opentest4j.AssertionFailedError: expected: <3> but was: <4>

Assertion condition defined as a Lambda expression in io.quarkus.it.kafka.KafkaConnectorTest expected: <3> but was: <5> within 10 seconds. - org.awaitility.core.ConditionTimeoutException

Details

org.awaitility.core.ConditionTimeoutException: Assertion condition defined as a Lambda expression in io.quarkus.it.kafka.KafkaConnectorTest expected: <3> but was: <5> within 10 seconds.
	at org.awaitility.core.ConditionAwaiter.await(ConditionAwaiter.java:167)
	at org.awaitility.core.AssertionCondition.await(AssertionCondition.java:119)
	at org.awaitility.core.AssertionCondition.await(AssertionCondition.java:31)
	at org.awaitility.core.ConditionFactory.until(ConditionFactory.java:1160)
	at org.awaitility.core.ConditionFactory.untilAsserted(ConditionFactory.java:790)
	at io.quarkus.it.kafka.KafkaConnectorTest.testDataForKeyed(KafkaConnectorTest.java:96)
Caused by: java.util.concurrent.TimeoutException

⚙️ JVM Integration Tests - JDK 25 Semeru

📦 integration-tests/reactive-messaging-kafka

❌ io.quarkus.it.kafka.KafkaConnectorTest.testRequestReply - History

iterable contents differ at index [0], expected: <reply-1> but was: <{"details":"Error id 82df9a9a-1523-4e9b-9214-3b338f5eec96-1, org.jboss.resteasy.spi.UnhandledException: io.smallrye.reactive.messaging.kafka.reply.KafkaRequestReplyTimeoutException: Timeout waiting for a reply for request with correlation ID: 0403eb21-8fd7-4190-b2b9-9f6d2c83dd29","stack":"org.jboss.resteasy.spi.UnhandledException: io.smallrye.reactive.messaging.kafka.reply.KafkaRequestReplyTimeoutException: Timeout waiting for a reply for request with correlation ID: 0403eb21-8fd7-4190-b2b9-9f6d2c83dd29\n\tat org.jboss.resteasy.core.ExceptionHandler.handleApplicationException(ExceptionHandler.java:107)\n\tat org.jboss.resteasy.core.ExceptionHandler.handleException(ExceptionHandler.java:344)\n\tat org.jboss.resteasy.core.SynchronousDispatcher.writeException(SynchronousDispatcher.java:205)\n\tat org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:452)\n\tat org.jboss.resteasy.core.Synchron... - org.opentest4j.AssertionFailedError

Details

org.opentest4j.AssertionFailedError: iterable contents differ at index [0], expected: <reply-1> but was: <{"details":"Error id 82df9a9a-1523-4e9b-9214-3b338f5eec96-1, org.jboss.resteasy.spi.UnhandledException: io.smallrye.reactive.messaging.kafka.reply.KafkaRequestReplyTimeoutException: Timeout waiting for a reply for request with correlation ID: 0403eb21-8fd7-4190-b2b9-9f6d2c83dd29","stack":"org.jboss.resteasy.spi.UnhandledException: io.smallrye.reactive.messaging.kafka.reply.KafkaRequestReplyTimeoutException: Timeout waiting for a reply for request with correlation ID: 0403eb21-8fd7-4190-b2b9-9f6d2c83dd29\n\tat org.jboss.resteasy.core.ExceptionHandler.handleApplicationException(ExceptionHandler.java:107)\n\tat org.jboss.resteasy.core.ExceptionHandler.handleException(ExceptionHandler.java:344)\n\tat org.jboss.resteasy.core.SynchronousDispatcher.writeException(SynchronousDispatcher.java:205)\n\tat org.jboss.resteasy.core.SynchronousDispatcher.invoke(SynchronousDispatcher.java:452)\n...

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mkouba requested review from Ladicek, cescoffier, manovotn and ozangunalp April 24, 2026 08:21

mkouba added the release/noteworthy-feature label Apr 24, 2026

quarkus-bot Bot added area/dependencies Pull requests that update a dependency file area/documentation area/infra-automation anything related to CI, bots, etc. that are used to automated our infrastructure labels Apr 24, 2026

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mkouba force-pushed the signals branch from 8c69053 to 010d3a1 Compare April 24, 2026 09:19

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mkouba force-pushed the signals branch from 010d3a1 to fcd2831 Compare April 24, 2026 10:14

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mkouba commented Apr 24, 2026

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Comment thread extensions/signals/runtime/src/main/java/io/quarkus/signals/runtime/impl/ReceiverManager.java Outdated

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quarkus-bot Bot added the triage/flaky-test label Apr 24, 2026

mkouba force-pushed the signals branch from fcd2831 to 6ee37fb Compare April 24, 2026 18:25

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Introduce quarkus-signals experimental extension#53788

Introduce quarkus-signals experimental extension#53788
mkouba wants to merge 1 commit intoquarkusio:mainfrom
mkouba:signals

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Definition of Done (taken from the WG proposal)

Missing pieces

Context propagation

Relationship between the new API, CDI events, and in-memory Reactive Messaging

Migration guide from @ConsumeEvent and Vert.x event bus

Unfinished parts

Signal emission methods

Resolution - the only difference from the CDI specification

API history and evolution

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quarkus-bot Bot commented Apr 24, 2026

Status for workflow Quarkus Documentation CI

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Status for workflow Quarkus CI

Failing Jobs

Failures

⚙️ Kubernetes Tests - JDK 25 Semeru #

📦 integration-tests/kubernetes/maven-invoker-way

Flaky tests - Develocity

⚙️ JVM Tests - JDK 25

📦 extensions/vertx-http/deployment

⚙️ JVM Tests - JDK 25 Semeru

📦 extensions/quartz/deployment

📦 extensions/vertx-http/deployment

⚙️ Native Tests - Messaging1

📦 integration-tests/reactive-messaging-kafka

⚙️ JVM Integration Tests - JDK 17

📦 integration-tests/reactive-messaging-kafka

⚙️ JVM Integration Tests - JDK 25

📦 integration-tests/reactive-messaging-kafka

⚙️ JVM Integration Tests - JDK 25 Semeru

📦 integration-tests/reactive-messaging-kafka

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mkouba commented Apr 24, 2026 •

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Migration guide from `@ConsumeEvent` and Vert.x event bus

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Status for workflow `Quarkus Documentation CI`

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Status for workflow `Quarkus CI`