[richfaces-issues] [JBoss JIRA] (RF-11933) Push: user-friendly topics initialization on startup

[Lukáš Fryč (JIRA)]

Lukáš Fryč created RF-11933:
-------------------------------

             Summary: Push: user-friendly topics initialization on startup
                 Key: RF-11933
                 URL: https://issues.jboss.org/browse/RF-11933
             Project: RichFaces
          Issue Type: Enhancement
      Security Level: Public (Everyone can see)
          Components: core
    Affects Versions: 4.2.0.CR1
            Reporter: Lukáš Fryč


Currently, when custom threads (like JMS) out of {{FacesContext}} context tries to initialize {{PushContext}} e.g. by {{TopicsContext.lookup()}}, initializations fails with:

{code}
11:12:39,189 ERROR [stderr] (MessageProducerThread) Exception in thread "MessageProducerThread" java.lang.ExceptionInInitializerError
11:12:39,191 ERROR [stderr] (MessageProducerThread) 	at org.richfaces.application.push.impl.PushContextFactoryImpl.getPushContext(PushContextFactoryImpl.java:89)
11:12:39,191 ERROR [stderr] (MessageProducerThread) 	at org.richfaces.application.push.TopicsContext.lookup(TopicsContext.java:79)
11:12:39,192 ERROR [stderr] (MessageProducerThread) 	at org.richfaces.demo.push.TopicsContextMessageProducer.sendMessage(TopicsContextMessageProducer.java:45)
11:12:39,192 ERROR [stderr] (MessageProducerThread) 	at org.richfaces.demo.push.MessageProducerRunnable.run(MessageProducerRunnable.java:57)
11:12:39,192 ERROR [stderr] (MessageProducerThread) 	at java.lang.Thread.run(Thread.java:662)
11:12:39,192 ERROR [stderr] (MessageProducerThread) Caused by: java.lang.NullPointerException
11:12:39,192 ERROR [stderr] (MessageProducerThread) 	at org.richfaces.application.push.impl.PushContextFactoryImpl.createInstance(PushContextFactoryImpl.java:74)
11:12:39,193 ERROR [stderr] (MessageProducerThread) 	at org.richfaces.application.push.impl.PushContextFactoryImpl.access$0(PushContextFactoryImpl.java:71)
11:12:39,193 ERROR [stderr] (MessageProducerThread) 	at org.richfaces.application.push.impl.PushContextFactoryImpl$PushContextHolder.<clinit>(PushContextFactoryImpl.java:43)
11:12:39,193 ERROR [stderr] (MessageProducerThread) 	... 5 more
{code}

and then any other try for accessing context fails with:

{code}
11:19:45,829 INFO  [javax.enterprise.resource.webcontainer.jsf.context] (http--0.0.0.0-8080-4) Exception when handling error trying to reset the response.: java.lang.NoClassDefFoundError: Could not initialize class org.richfaces.application.push.impl.PushContextFactoryImpl$PushContextHolder
	at org.richfaces.application.push.impl.PushContextFactoryImpl.getPushContext(PushContextFactoryImpl.java:89) [richfaces-core-impl-4.2.0-SNAPSHOT.jar:]
	at org.richfaces.renderkit.PushRendererBase.getPushHandlerUrl(PushRendererBase.java:55) [richfaces-components-ui-4.2.0-SNAPSHOT.jar:]
	at org.richfaces.renderkit.html.PushRenderer.encodeEnd(PushRenderer.java:89) [richfaces-components-ui-4.2.0-SNAPSHOT.jar:]
{code}

----

Users can initialize {{PushContext}} with {{web.xml}} param:
* {{org.richfaces.push.initializeOnStartup}}
** we don't initialize on startup automatically, since not every app needs Push

but current impl is quite a bit unfriendly, since it throws the exceptions above and do not get any solution.

----

I would recommend following improvements:
* sensible default = automatically initialize on startup when {{org.richfaces.push.jms.enabled = true}}
** when user configures app to use Push JMS integration, it's clear he wants to use Push
* log error with message describing how to use context-param {{org.richfaces.push.initializeOnStartup}}
** to allow user configure this option without need for studying documentation
* throw application-specific unchecked exception (e.g. {{PushContextInitializationException}})
** it will allow to handle these exceptions by application (waiting for initialization)
* hold {{PushContext}} singleton reference in {{AtomicReference}} instead of in [static inner class|https://github.com/richfaces/core/blob/develop/impl/src/main/java/org/richfaces/application/push/impl/PushContextFactoryImpl.java#L43]
** allows app to initialize context once {{FacesContext}} available and do not fail with {{NoClassDefFoundError: Could not initialize class PushContextFactoryImpl$PushContextHolder}}

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