[richfaces-issues] [JBoss JIRA] (RF-13674) a4j:push broken on WebLogic 12c

[Val Blant (JIRA)]

Val Blant created RF-13674:
------------------------------

             Summary: a4j:push broken on WebLogic 12c
                 Key: RF-13674
                 URL: https://issues.jboss.org/browse/RF-13674
             Project: RichFaces
          Issue Type: Bug
      Security Level: Public (Everyone can see)
          Components: component-push/poll
    Affects Versions: 4.2.0.Final
         Environment: WebLogic 12c
            Reporter: Val Blant


<a4j:push />  works properly on Tomcat 7, but fails on WebLogic 12c. 

{code:title=Page.xhtml|borderStyle=solid}
<a4j:push address="systemLinks" >  
  <a4j:ajax event="dataavailable" render="systemLinksPanel" />  
</a4j:push>  
  
<a4j:outputPanel id="systemLinksPanel">  
     stuff here  
</a4j:outputPanel>  
{code}

{code:title=Java Code}
TopicKey topicKey = new TopicKey("systemLinks");  
TopicsContext topicsContext = TopicsContext.lookup();  
topicsContext.publish(topicKey, "fly, you fools!");  
{code}

On Tomcat 7 this work perfectly, and always refreshes '_systemLinksPanel_' when data is published. 

On Weblogic 12c the data is not flushed correctly. If you use Wireshark, you'd see the following response coming back from the server:
{panel:title=Tomcat 7}
3b
<"topic":"systemLinks","data":"fly, you fools!","number":0>
0
{panel}

{panel:title=Weblogic 12c}
003b
<"topic":"systemLinks","data":"fly, you fools!","number":0>
{panel}

*Note the missing zero terminator line in the WebLogic response!*

I narrowed down the problem to the following:
{code:title=org.richfaces.application.push.impl.RequestImpl}
    public synchronized void onBroadcast(AtmosphereResourceEvent<HttpServletRequest, HttpServletResponse> event) {
        MessageDataScriptString serializedMessages = (MessageDataScriptString) event.getMessage();
        getSession().clearBroadcastedMessages(serializedMessages.getLastSequenceNumber());

        hasActiveBroadcaster = false;

        if (isPolling()) {
            event.getResource().resume(); // <= THIS LINE
        } else {
            postMessages();
        }
    }
{code}

There is nothing wrong with this in principle, but it does not work due to a bug in Atmosphere 0.8.4. Calling _AtmosphereResource.resume()_ at this point seems reasonable, since it is supposed to properly finish/commit the _HttpServletResponse_.  However, this does not work on WebLogic 12c and leads to incorrectly flushed data demonstrated above. 

The underlying problem seems to be the fact that _AtmosphereResource.resume()_ method interrupts the thread which flushed the socket Writer before a call to _asyncContext.complete()_ is made:
{code}
public AtmosphereResource resume() {
....
 if (!b.isDestroyed()) {
     b.removeAtmosphereResource(event.getResource());
 }
....
 asyncSupport.action(this); // <= This is where asyncContext.complete() is called
}
{code}

I have verified that calling _asyncContext.complete()_ before we clean up Atmosphere resources fixes the problem.

Here's the fix, which needs to go into _RequestImpl.onBroadcast_:
{code:title=org.richfaces.application.push.impl.RequestImpl}
    public synchronized void onBroadcast(AtmosphereResourceEvent<HttpServletRequest, HttpServletResponse> event) {
  ..............
        if (isPolling()) {

// This is the workaround. Completing AsyncContext before cleaning up Atmosphere resources
// seems to make this work everywhere.
//
AsyncContext asyncContext = (AsyncContext) 
	event
		.getResource()
		.getRequest()
		.getAttribute("org.atmosphere.container.asyncContext");

   if ( asyncContext != null ) {
	asyncContext.complete();
   }

            event.getResource().resume();
        } else {
            postMessages();
        }
    }
  ..............
{code}

I am attaching a very simple WAR file that demonstrates the problem clearly. The demo app does not use Richfaces, b/c I wanted to remove all unnecessary complexity. Instead I created a couple of simple classes that mimic the behavior of _org.richfaces.webapp.PushHandlerFilter_ and _org.richfaces.application.push.impl.RequestImpl_. In the demo app, _MeteorRequest = RequestImpl_, which is where the fix needs to go.




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