Websocket support for Vaadin 8 is broken with pax-web 8.0.33

[rh-desoftware]

When deploying a Vaadin 8 application into Karaf 4.4.8 with pax-web 8.0.33 the following exception occurs when access the web application:

The problem can be reproduces with this sample project: https://github.com/rh-desoftware/vaadin8_karaf_demo

09:24:14.810 INFO [qtp1595367122-443] Installed AtmosphereHandler com.vaadin.server.communication.PushAtmosphereHandler mapped to context-path: /*
09:24:14.812 INFO [qtp1595367122-443] Installed the following AtmosphereInterceptor mapped to AtmosphereHandler com.vaadin.server.communication.PushAtmosphereHandler
09:24:14.847 INFO [qtp1595367122-443] Atmosphere is using org.atmosphere.util.VoidAnnotationProcessor for processing annotation
09:24:14.856 INFO [qtp1595367122-443] Using ForkJoinPool  java.util.concurrent.ForkJoinPool. Set the org.atmosphere.cpr.broadcaster.maxAsyncWriteThreads to -1 to fully use its power.
09:24:14.862 INFO [qtp1595367122-443] Installed WebSocketProtocol org.atmosphere.websocket.protocol.SimpleHttpProtocol
09:24:14.873 WARN [qtp1595367122-443] Failed to create AsyncSupport class: class org.atmosphere.container.JSR356AsyncSupport, error: java.lang.reflect.InvocationTargetException
09:24:14.874 ERROR [qtp1595367122-443] Real error: Unable to configure jsr356 at that stage. ServerContainer is null
java.lang.IllegalStateException: Unable to configure jsr356 at that stage. ServerContainer is null
        at org.atmosphere.container.JSR356AsyncSupport.<init>(JSR356AsyncSupport.java:53) ~[!/:2.4.30.vaadin4]
        at org.atmosphere.container.JSR356AsyncSupport.<init>(JSR356AsyncSupport.java:42) ~[!/:2.4.30.vaadin4]
        at jdk.internal.reflect.DirectConstructorHandleAccessor.newInstance(DirectConstructorHandleAccessor.java:62) ~[?:?]
        at java.lang.reflect.Constructor.newInstanceWithCaller(Constructor.java:502) ~[?:?]
        at java.lang.reflect.Constructor.newInstance(Constructor.java:486) ~[?:?]
        at org.atmosphere.cpr.DefaultAsyncSupportResolver.newCometSupport(DefaultAsyncSupportResolver.java:237) ~[!/:2.4.30.vaadin4]
        at org.atmosphere.cpr.DefaultAsyncSupportResolver.resolveWebSocket(DefaultAsyncSupportResolver.java:308) ~[!/:2.4.30.vaadin4]
        at org.atmosphere.cpr.DefaultAsyncSupportResolver.resolve(DefaultAsyncSupportResolver.java:294) ~[!/:2.4.30.vaadin4]
        at org.atmosphere.cpr.AtmosphereFramework.autoDetectContainer(AtmosphereFramework.java:2092) ~[!/:2.4.30.vaadin4]
        at org.atmosphere.cpr.AtmosphereFramework.init(AtmosphereFramework.java:914) ~[!/:2.4.30.vaadin4]
        at org.atmosphere.cpr.AtmosphereFramework.init(AtmosphereFramework.java:838) ~[!/:2.4.30.vaadin4]
        at com.vaadin.server.communication.PushRequestHandler.initAtmosphere(PushRequestHandler.java:206) ~[!/:8.14.0]
        at com.vaadin.server.communication.PushRequestHandler.<init>(PushRequestHandler.java:79) ~[!/:8.14.0]
        at com.vaadin.server.VaadinServletService.createRequestHandlers(VaadinServletService.java:68) ~[!/:8.14.0]
        at com.vaadin.server.VaadinService.init(VaadinService.java:219) ~[!/:8.14.0]
        at com.vaadin.server.VaadinServlet.createServletService(VaadinServlet.java:417) ~[!/:8.14.0]
        at com.vaadin.server.VaadinServlet.createServletService(VaadinServlet.java:396) ~[!/:8.14.0]
        at com.vaadin.server.VaadinServlet.init(VaadinServlet.java:226) ~[!/:8.14.0]
        at org.ops4j.pax.web.service.spi.servlet.OsgiInitializedServlet.init(OsgiInitializedServlet.java:68) ~[?:?]
        at org.eclipse.jetty.servlet.ServletHolder.initServlet(ServletHolder.java:632) ~[?:?]
        at org.eclipse.jetty.servlet.ServletHolder.getServlet(ServletHolder.java:486) ~[?:?]
        at org.eclipse.jetty.servlet.ServletHolder.prepare(ServletHolder.java:759) ~[?:?]
        at org.ops4j.pax.web.service.jetty.internal.PaxWebServletHolder.prepare(PaxWebServletHolder.java:295) ~[?:?]
        at org.ops4j.pax.web.service.jetty.internal.PaxWebServletHandler.doHandle(PaxWebServletHandler.java:330) ~[?:?]
        at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:143) ~[?:?]
        at org.eclipse.jetty.security.SecurityHandler.handle(SecurityHandler.java:600) ~[?:?]
        at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127) ~[?:?]
        at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:235) ~[?:?]
        at org.eclipse.jetty.server.session.SessionHandler.doHandle(SessionHandler.java:1624) ~[?:?]
        at org.eclipse.jetty.server.handler.ScopedHandler.nextHandle(ScopedHandler.java:233) ~[?:?]
        at org.eclipse.jetty.server.handler.ContextHandler.doHandle(ContextHandler.java:1440) ~[?:?]
        at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:188) ~[?:?]
        at org.eclipse.jetty.servlet.ServletHandler.doScope(ServletHandler.java:505) ~[?:?]
        at org.eclipse.jetty.server.session.SessionHandler.doScope(SessionHandler.java:1594) ~[?:?]
        at org.eclipse.jetty.server.handler.ScopedHandler.nextScope(ScopedHandler.java:186) ~[?:?]
        at org.eclipse.jetty.server.handler.ContextHandler.doScope(ContextHandler.java:1355) ~[?:?]
        at org.eclipse.jetty.server.handler.ScopedHandler.handle(ScopedHandler.java:141) ~[?:?]
        at org.eclipse.jetty.server.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:234) ~[?:?]
        at org.ops4j.pax.web.service.jetty.internal.PrioritizedHandlerCollection.handle(PrioritizedHandlerCollection.java:96) ~[?:?]
        at org.eclipse.jetty.server.handler.HandlerWrapper.handle(HandlerWrapper.java:127) ~[?:?]
        at org.eclipse.jetty.server.Server.handle(Server.java:516) ~[?:?]
        at org.eclipse.jetty.server.HttpChannel.lambda$handle$1(HttpChannel.java:487) ~[?:?]
        at org.eclipse.jetty.server.HttpChannel.dispatch(HttpChannel.java:732) ~[?:?]
        at org.eclipse.jetty.server.HttpChannel.handle(HttpChannel.java:479) ~[?:?]
        at org.eclipse.jetty.server.HttpConnection.onFillable(HttpConnection.java:277) ~[?:?]
        at org.eclipse.jetty.io.AbstractConnection$ReadCallback.succeeded(AbstractConnection.java:311) ~[?:?]
        at org.eclipse.jetty.io.FillInterest.fillable(FillInterest.java:105) ~[?:?]
        at org.eclipse.jetty.io.ChannelEndPoint$1.run(ChannelEndPoint.java:104) ~[?:?]
        at org.eclipse.jetty.util.thread.QueuedThreadPool.runJob(QueuedThreadPool.java:883) ~[?:?]
        at org.eclipse.jetty.util.thread.QueuedThreadPool$Runner.run(QueuedThreadPool.java:1034) ~[?:?]
        at java.lang.Thread.run(Thread.java:1583) [?:?]

[grgrzybek]

Thanks for the report.
For now I have to finish my normal work, but I hope to get back to this one...

In the meantime - if you know what could/should be fixed, we'll welcome a PR to review ;)

[rh-desoftware]

I cannot find an place in the code that sets for Jetty the ServerContainer into the servletcontext.

Is it only done for undertow?

org.ops4j.pax.web/pax-web-undertow-websocket/src/main/java/org/ops4j/pax/web/service/undertow/websocket/internal/WebSocketsExtension.java

Line 94 in d5f88c4

deploymentInfo.addServletContextAttribute(ServerContainer.class.getName(), container);

?

[grgrzybek]

For Jetty it should be automatic - javax-websocket-server-impl-9.4.58.v20250814.jar/META-INF/services/javax.servlet.ServletContainerInitializer should be picked up by your WAB and this is how Jetty itself through ServletContainerInitializer adds relevant attribute to the context.

[rh-desoftware]

I have time tomorrow to debug the issue with WebSocket support for Vaadin 8 and pax-web 8.0.33. However, I'm not really sure where to start, especially regarding the part where Jetty should set the ServerContainer into the servlet context. Does anyone have suggestions or could point me to where in the code this setup should happen for Jetty? Any hints are welcome!

Thanks a lot!

[grgrzybek]

Thanks for your time. Please start with org.eclipse.jetty.websocket.jsr356.server.deploy.WebSocketServerContainerInitializer#onStartup() from org.eclipse.jetty.websocket:javax-websocket-server-impl artifact.

Also turning on a debug/trace logger for org.ops4j.pax.web category, will give you a lot of information - mostly about what metadata is found when preparing web contexts.

[rh-desoftware]

I did the following:

• Cloned pax-web and switched to tag 8.0.33 (the version of pax-web in Karaf 4.4.8)
• Opened pax-web in IntelliJ and set a breakpoint in org.eclipse.jetty.websocket.jsr356.server.deploy.WebSocketServerContainerInitializer#onStartup() from javax-websocket-server-impl-9.4.57.v20241219.jar
• Enabled debug/trace for org.ops4j.pax.web in Karaf
• Started Karaf in debug mode
• Connected IntelliJ with remote debugging to Karaf
• Installed the vaadin8_karaf_demo_whiteboard in Karaf
• Opened the Vaadin application in the browser

The breakpoint in WebSocketServerContainerInitializer#onStartup() was not reached.
Here is the content of karaf.log: https://gist.github.com/rh-desoftware/489bc14fb03da2a687e4ea9d2d9e6dc7

[grgrzybek]

Thanks!

mvn:org.eclipse.jetty.websocket/javax-websocket-server-impl/9.4.57.v20241219 bundle is installed, so it's fine

New context is being created here:

2026-01-22T16:37:12,095 | INFO  | paxweb-config-1-thread-1 | ServerModel                      | 108 - org.ops4j.pax.web.pax-web-spi - 8.0.33 | Created new ServletContextModel{id=ServletContextModel-6,contextPath='/vaadin-8.14.0'}

Here's your whiteboard content:

2026-01-22T16:37:12,096 | INFO  | paxweb-config-1-thread-1 | JettyServerController            | 105 - org.ops4j.pax.web.pax-web-jetty - 8.0.33 | Receiving Batch{"Registration of OsgiContextModel{WB,id=OCM-4,name='com.vaadin',path='/vaadin-8.14.0',bundle=com.vaadin.shared,ref=[org.osgi.service.http.context.ServletContextHelper]}", size=2}
2026-01-22T16:37:12,116 | INFO  | paxweb-config-1-thread-1 | JettyServerController            | 105 - org.ops4j.pax.web.pax-web-jetty - 8.0.33 | Receiving Batch{"Registration of ServletModel{id=ServletModel-7,name='default-bb63fb86-9d44-4400-b377-75d57e0cffbb',urlPatterns=[/VAADIN/vaadinPush.js],contexts=[{WB,OCM-4,com.vaadin,/vaadin-8.14.0}]}", size=1}
2026-01-22T16:37:12,181 | INFO  | paxweb-config-1-thread-1 | JettyServerController            | 105 - org.ops4j.pax.web.pax-web-jetty - 8.0.33 | Receiving Batch{"Registration of ServletModel{id=ServletModel-8,name='default-66b8ac87-48f3-43f5-8a85-fd2e26fba0a6',urlPatterns=[/VAADIN/vaadinPush.js.gz],contexts=[{WB,OCM-4,com.vaadin,/vaadin-8.14.0}]}", size=1}
2026-01-22T16:37:12,183 | INFO  | paxweb-config-1-thread-1 | JettyServerController            | 105 - org.ops4j.pax.web.pax-web-jetty - 8.0.33 | Receiving Batch{"Registration of ServletModel{id=ServletModel-9,name='default-699b3465-63f3-4b10-b60d-6581d28a5dee',urlPatterns=[/VAADIN/vaadinPush.debug.js],contexts=[{WB,OCM-4,com.vaadin,/vaadin-8.14.0}]}", size=1}
2026-01-22T16:37:12,184 | INFO  | paxweb-config-1-thread-1 | JettyServerController            | 105 - org.ops4j.pax.web.pax-web-jetty - 8.0.33 | Receiving Batch{"Registration of ServletModel{id=ServletModel-10,name='default-ffbf9f7e-d2fe-4602-8d8e-5f01ca7d767a',urlPatterns=[/VAADIN/vaadinPush.debug.js.gz],contexts=[{WB,OCM-4,com.vaadin,/vaadin-8.14.0}]}", size=1}
2026-01-22T16:37:12,185 | INFO  | paxweb-config-1-thread-1 | JettyServerController            | 105 - org.ops4j.pax.web.pax-web-jetty - 8.0.33 | Receiving Batch{"Registration of ServletModel{id=ServletModel-12,name='default-420be9ab-8403-4144-9c9a-13f575e262b2',urlPatterns=[/VAADIN/vaadinBootstrap.js],contexts=[{WB,OCM-4,com.vaadin,/vaadin-8.14.0}]}", size=1}
2026-01-22T16:37:12,186 | INFO  | paxweb-config-1-thread-1 | JettyServerController            | 105 - org.ops4j.pax.web.pax-web-jetty - 8.0.33 | Receiving Batch{"Registration of ServletModel{id=ServletModel-13,name='default-d0de0067-a11d-47ee-a1c9-7614fac08384',urlPatterns=[/VAADIN/vaadinBootstrap.js.gz],contexts=[{WB,OCM-4,com.vaadin,/vaadin-8.14.0}]}", size=1}
2026-01-22T16:37:12,186 | INFO  | paxweb-config-1-thread-1 | JettyServerController            | 105 - org.ops4j.pax.web.pax-web-jetty - 8.0.33 | Receiving Batch{"Registration of ServletModel{id=ServletModel-14,name='default-906f446b-d4d9-4549-8b58-a35ec35f8a20',urlPatterns=[/VAADIN/themes/valo/*],contexts=[{WB,OCM-4,com.vaadin,/vaadin-8.14.0}]}", size=1}
2026-01-22T16:37:12,188 | INFO  | paxweb-config-1-thread-1 | JettyServerController            | 105 - org.ops4j.pax.web.pax-web-jetty - 8.0.33 | Receiving Batch{"Registration of ServletModel{id=ServletModel-15,name='default-b46fe5ef-7c42-4e5b-9db3-9a3b4d110c2a',urlPatterns=[/VAADIN/widgetsets/com.vaadin.DefaultWidgetSet/*],contexts=[{WB,OCM-4,com.vaadin,/vaadin-8.14.0}]}", size=1}
2026-01-22T16:37:12,189 | INFO  | paxweb-config-1-thread-1 | JettyServerController            | 105 - org.ops4j.pax.web.pax-web-jetty - 8.0.33 | Receiving Batch{"Registration of OsgiContextModel{WB,id=OCM-16,name='Vaadin8DemoWhiteboard',path='/vaadin8demo/whiteboard',bundle=com.desoft.vaadin8_karaf_demo_whiteboard,ref=[org.osgi.service.http.context.ServletContextHelper]}", size=2}
2026-01-22T16:37:12,237 | INFO  | paxweb-config-1-thread-1 | JettyServerController            | 105 - org.ops4j.pax.web.pax-web-jetty - 8.0.33 | Receiving Batch{"Registration of ServletModel{id=ServletModel-19,name='MyUIServlet',urlPatterns=[/*, /VAADIN/*],contexts=[{WB,OCM-1,default,/}]}", size=1}

So you're not whiteboard-registering any websocket.

I was thinking you're using WAB example, where servlet container initializers are automatically detected and processed (this Jetty Websocket SCI would be reached by OSGi wires or Pax Web would add it to you WAB dynamically).

For Whiteboard you can't use anything standard, because https://docs.osgi.org/specification/osgi.cmpn/8.0.0/service.http.whiteboard.html doesn't mention WebSockets at all.

You have to use something a bit Pax Web specific - see an example here: https://github.com/ops4j/org.ops4j.pax.web/blob/web-8.0.33/pax-web-itest/pax-web-itest-container/pax-web-itest-container-common/src/main/java/org/ops4j/pax/web/itest/container/websockets/AbstractWebSocketWhiteBoardIntegrationTest.java

Roughly you register your @javax.websocket.server.ServerEndpoint annotated class like this:

SimpleWebSocket simpleWebSocket = new SimpleWebSocket();
Dictionary<String, Object> filter = new Hashtable<>();
filter.put(PaxWebConstants.SERVICE_PROPERTY_WEBSOCKET, "true");
context.registerService(Object.class.getName(), simpleWebSocket, filter);

The problem is that Vaadin doesn't do it - why should it use Pax Web specific API?

I'd try with WAB approach.

[rh-desoftware]

I added a WebSocket endpoint to vaadin8_karaf_demo_whiteboard. The VaadinServlet now also works with WebSockets :).

It would be great if pax-web would always activate WebSocket support when a service has the property org.ops4j.pax.web.http.whiteboard.websocket=true.

[grgrzybek]

It would be great if pax-web would always activate WebSocket support when a service has the property org.ops4j.pax.web.http.whiteboard.websocket=true.

I don't quite understand - isn't it what Pax Web is doing? This property + proper annotation from JSR 356...

[rh-desoftware]

I added also an websocket to the vaadin8_karaf_demo_war. However for wars it is not working.
Here the karaf.log

[rh-desoftware]

It would be great if pax-web would always activate WebSocket support when a service has the property org.ops4j.pax.web.http.whiteboard.websocket=true.

I don't quite understand - isn't it what Pax Web is doing? This property + proper annotation from JSR 356...

Enabling websocket support by adding the property org.ops4j.pax.web.http.whiteboard.websocket=true to the VaadinServlet (VaadinServlet has no JSR 356 annotation).

[rh-desoftware]

The PR #2137 implements a possible solution for the Vaadin 8 issue.
With this PR, PAX-WEB provides WebSocket support for every service that has set the service property org.ops4j.pax.web.http.whiteboard.websocket=true. It is no longer necessary that the service is annotated with ServerEndpoint.

Would this be a possible solution from the perspective of the maintainers of the PAX-WEB project?

[grgrzybek]

Thanks @rh-desoftware for the PR - I get your idea, but definitely this PR should not change versions of all the poms ;)

I have to finish one important task outside of Pax Web and then I'm back to update versions, fix session management in Pax Web 10 and looks like Pax Web 8 needs another (4th unplanned) release ;)

But give me please few days.