[jbossseam-issues] [JBoss JIRA] Updated: (JBSEAM-1556) Multiple instances of Seam PhaseListener permitted to be registered in JSF lifecycle

[Neil Griffin (JIRA)]

     [ http://jira.jboss.com/jira/browse/JBSEAM-1556?page=all ]

Neil Griffin updated JBSEAM-1556:
---------------------------------

    Attachment: SeamPortletPhaseListener.java

Search for "JBSEAM-1556" in the attached file for fixes.

> Multiple instances of Seam PhaseListener permitted to be registered in JSF lifecycle
> ------------------------------------------------------------------------------------
>
>                 Key: JBSEAM-1556
>                 URL: http://jira.jboss.com/jira/browse/JBSEAM-1556
>             Project: JBoss Seam
>          Issue Type: Bug
>          Components: JSF
>    Affects Versions: 1.2.1.GA
>         Environment: WinXP / Liferay 4.3.0 / Tomcat 6.0.13
>            Reporter: Neil Griffin
>         Attachments: AbstractSeamPhaseListener.java, SeamPhaseListener.java, SeamPortletPhaseListener.java
>
>
> Background: I found this problem when trying to package-up the Seam "Registration" example as a portlet under Liferay Portal.
> The AbstractSeamPhaseListener class has a nice warning in the constructor, which alerts you in case more than one Seam-related PhaseListener is registered in the JSF lifecycle:
>    private static boolean exists = false;
>    protected AbstractSeamPhaseListener()
>    {
>       if (exists) log.warn("There should only be one Seam phase listener per application");
>       exists=true;
>    }
> While this is good and helpful, the code needs to be improved to ENSURE that only one Seam-related PhaseListener is permitted to execute.
> Case in point: When running in a portlet environment and using MyFaces, JSF PhaseListeners get registered TWICE, due to the way MyFaces initializes itself:
> 1. MyFaces has a StartupServletContextListener that initializes the JSF framework (the first time).
> 2. The MyFacesGenericPortlet.initMyFaces() method initializes the JSF framework (a second time). 
> Normally this would not be a big deal, but Seam has a restriction such that only one Seam-related PhaseListener may be active in the JSF Lifecycle. Because of the double-initialization that MyFaces is performing in the portlet scenario, any <phase-listener> elements found in the faces-config.xml file get registered twice! In Seam, this can cause all kinds of runtime problems.
> There are two ways that I can think of to fix this:
> 1. Only let the first PhaseListener "win", and prevent any others from executing their phase handler callbacks (even though registered in the JSF lifecycle).
> 2. Unregister PhaseListeners that don't win. This is hard to do though -- it can't be done in the constructor, because the PhaseListener can't unregister itself at that time, because it hasn't been added to the lifecycle yet.
> 2. 

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