6 Replies Latest reply on Nov 6, 2012 5:40 PM by tony.herstell1

Two conversations created instead of one with conversation.begin() in @PostConstruct method

lucaster Nov 6, 2012 8:29 AM

Before issuing a bug, I'd like someone to try the following, which exposes a weird behaviour in Weld's conversation management.

All will work fine if you use this bean/page as they are, but if you move the outputText with id 'convout' inside the form, two conversations will be started instead of one!!! The first conversation will be righfully created when the pages is requested the rist time. But another one will be created when you press the 'Increment' button.

(I'm experiencing this with JBoss AS 7.1.1.Final, JBoss Developer Studio 5, with a Java EE Web Project)

ConvTest.java

@Named
@ConversationScoped
public class ConvTest implements Serializable {

    private static final long serialVersionUID = 2866431447137331469L;

    @Inject
    private Conversation conversation;

    private int counter;

    @PostConstruct
    public void postCon() {
        if (conversation.isTransient())
            conversation.begin();
    }

    public void increment() {
        counter++;
    }

    public Conversation getConversation() {
        return conversation;
    }

    public int getCounter() {
        return counter;
    }

}

index.xhtml

<?xml version="1.0" encoding="UTF-8"?>
<html xmlns="http://www.w3.org/1999/xhtml"
    xmlns:ui="http://java.sun.com/jsf/facelets"
    xmlns:f="http://java.sun.com/jsf/core"
    xmlns:h="http://java.sun.com/jsf/html">
<h:head>
</h:head>
<h:body>

    <!-- Moving this outputText inside the form causes the side effect -->
    <h:outputText value="#{convTest.conversation}" id="convout"/>

    <h:form>
        <h:commandButton value="Increment" action="#{convTest.increment}" />        
    </h:form>

    <h:outputText value="#{convTest.counter}" />

</h:body>
</html>

1. Re: Two conversations created instead of one with conversation.begin() in @PostConstruct method

luksa Nov 6, 2012 8:41 AM (in response to lucaster)

Yup, exactly as you say. A second conversation is created. Please file an issue and I'll take a look at it.
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2. Re: Two conversations created instead of one with conversation.begin() in @PostConstruct method

luksa Nov 6, 2012 9:34 AM (in response to luksa)

Ah, yes. When the <form> tag is rendered, the conversation hasn't been started, since ConvTest hasn't been instantiated yet (and @PostConstruct hasn't been invoked yet). As a result, the action url of the <form> tag contains no cid parameter, because there's no conversation active when the url is generated.

Need to figure out what, if anything, we should do about this.
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3. Re: Two conversations created instead of one with conversation.begin() in @PostConstruct method

lucaster Nov 6, 2012 9:53 AM (in response to luksa)

Thanks for the clarification!

As a matter of fact, the side effect also occurs when the outputText is after the </h:form>
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4. Re: Two conversations created instead of one with conversation.begin() in @PostConstruct method

luksa Nov 6, 2012 9:57 AM (in response to lucaster)

Yes, of course. The key thing here is that the conversation must be long-running before rendering the starting form tag.

Basically, the main problem with your approach is that you are starting the conversation in the render-response jsf phase. Ideally, you should start the conversation before this phase, otherwise the urls in html will not have the cid parameter, which is necessary for propagating the conversation.
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5. Re: Two conversations created instead of one with conversation.begin() in @PostConstruct method

mkouba Nov 6, 2012 10:23 AM (in response to luksa)

I think you might also use <f:param name="cid" value="#{javax.enterprise.context.conversation.id}"/> inside the commandButton provided you have the outputText before commandButton. But Marko is right that this approach is not convenient...

See also my blog post about ajax-related issues you might encounter: Seam vs Weld: ajax and conversations in JSF view
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6. Re: Two conversations created instead of one with conversation.begin() in @PostConstruct method

tony.herstell1 Nov 6, 2012 5:40 PM (in response to mkouba)

Going with KISS...

I land on a page via a menu that calls an "init" function in a controller...

 // A good place to START a conversation from. ** land here off a menu
    // click...
    public String init() {
        this.logger.info(">>>init");
        if (!this.conversation.isTransient()) {
            this.logger.info("Existing conversation found:" + this.conversation.getId() + " Ending it...");
            this.conversation.end();
        }
        this.logger.info("+++CONVERSATION START");
        this.conversation.begin(); // START THE LONG RUNNING CONVERSATION
        this.logger.info("conversation:" + this.conversation.getId());
        this.setupXXXXValues();
        this.logger.info("<<<init");
        return "pretty:manageXXXXs";
    }

and yes Buttons need the cid applied (especailly if you use prettyfaces)

            <ui:fragment rendered="#{xxxManagementController.CRUDMode eq 'DELETE'}">
               <p:commandButton id="deleteButton" update=":xxxxForm:xxxxxPanel :messagesForm" icon="ui-icon ui-icon-disk" action="#{xxxxManagementController.deleteXxxx(xxxxx)}"
                  value="#{messages.button_delete} #{messages.xxxx}" onstart="return confirm('#{messages.are_you_really_sure}')">
                  <f:param name="cid" value="#{xxxxxxManagementController.cid}" /> <!-- FORCE ConverstionId to be added -->
               </p:commandButton>
            </ui:fragment>

//Tell prettyfaces to use this bean when the pattern matches and show the manage xxxx page. Also support a Query Param (cid).
@URLMappings(mappings = { @URLMapping(id = "manageXXXs", pattern = "/xxxx/manage", viewId = "/pages/xxxx/manageXxxx.xhtml"),

Keeps it very simple though and avoida a lot of problems with Conversation Handling in JEE 6 Weld.

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