Create a nested conversation from JPDL pageflow ?

[gjeudy]

Hi,

I want to reuse a backing SFSB from a pageflow. My goal is to have 1 or more instances of the same backing SFSB through the course of the pageflow.

What would be the best approach to solve this problem ? I can use @Role to reference the SFSB as a different name, when the name is different and matches a @Role name a new instance is created. In this model all instances of the bean live in the same conversation.

Could I achieve this re-usability using a nested conversation instead ? With this approach each instance would live in it's own nested conversation and no @Role trick would have to be used. Is it possible to create a nested conversation from a JPDL pageflow ? I tried to trigger a nested conversation with an action in the JPDL pageflow:

<page name="addProductFamilyRel" view-id="/addProductFamilyRel.xhtml">

             <transition name="prev" to="editProduct" />

             <transition name="next" to="addCoverageRel">

                <action expression="#{productAction.saveProductFamilyRel}" />

                <action expression="#{reusablebean.beginNestedConversation}" />

             </transition>

             <transition name="cancel" to="end" />

   </page>

On the transition reusable bean begins a nested conversation through annotated method.

@Begin(nested=true)

public void beginNestedConversation()

The above caused seam to redirect to the current page in the JPDL pageflow even if transition next was submitted.

Has anyone played with similar setups ? I might be missing understanding but it looks like its not possible to use nested conversations from JPDL.

Best regards,
-Guillaume

[barbacena]

I am waiting a answer for this as well.

Nesting pageflow

[blabno]

This is how i nest conversations in jPDL. Take a look at the editCountry node.

<?xml version="1.0" encoding="UTF-8"?>
<pageflow-definition
    xmlns="http://jboss.com/products/seam/pageflow"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://jboss.com/products/seam/pageflow http://jboss.com/products/seam/pageflow-2.0.xsd"
    name="browseCountries">
    
    <start-page name="countriesList" view-id="/admin/manageCountries/countriesList.xhtml">
        <transition name="remove" to="confirmCountriesRemoval"/>
        <transition name="edit" to="editCountry"/>
        <transition name="add" to="editCountry">
            <action expression="#{countryBrowser.initAddCountryAction}"/>
        </transition>
        <transition name="finish" to="end"/>
    </start-page>
    
    <page name="confirmCountriesRemoval" view-id="/admin/manageCountries/confirmCountriesRemoval.xhtml" no-conversation-view-id="/admin/index.xhtml">
        <transition name="next" to="countriesList">
            <action expression="#{countryBrowser.removeSelectedCountries}"/>
        </transition>
        <transition name="cancel" to="countriesList"/>
    </page>   
    
    <process-state name="editCountry">        
        <sub-process name="editCountry"/>     
        <transition to="countriesList"/>
    </process-state>
    
    <page name="end" view-id="/admin/home.xhtml">
        <end-conversation/>
        <redirect/>
    </page>
    
</pageflow-definition>

editCountry.jpdl.xml

<?xml version="1.0" encoding="UTF-8"?>
<pageflow-definition
    xmlns="http://jboss.com/products/seam/pageflow"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xsi:schemaLocation="http://jboss.com/products/seam/pageflow
    http://jboss.com/products/seam/pageflow-2.0.xsd"
    name="editCountry">
    
    <start-state>
        <transition to="editForm">
            <action expression="#{countryManager.init}"/>
        </transition>
    </start-state>
    
    <page name="editForm" view-id="/admin/manageCountries/editCountry.xhtml">
        <transition name="cancel" to="end">
            <action expression="#{countryManager.revert}"/>
        </transition>
        <transition name="next" to="end">
            <action expression="#{countryManager.save}"/>
        </transition>
        <transition name="add" to="editRegion">
            <action expression="#{countryManager.initAddRegionAction}"/>
        </transition>
        <transition name="edit" to="editRegion"/>
        <transition name="remove" to="confirmRegionsRemoval"/>
    </page>
    
    <process-state name="editRegion">
        <sub-process name="editRegion"/>
        <transition to="editForm"/>
    </process-state>
    
    <page name="confirmRegionsRemoval" view-id="/admin/manageCountries/confirmRegionsRemoval.xhtml">
        <transition name="cancel" to="editForm"/>
        <transition name="next" to="editForm">
            <action expression="#{countryManager.removeSelectedRegions}"/>
        </transition>
    </page>
    
    <end-state name="end"/>
    
</pageflow-definition>

[gjeudy]

Hi,

Thanks Bernard for your input but your solution does not create a nested conversation (unless you omitted some code/XML in your example ?). The beans participating in the subprocess are still part of the parent conversation/pageflow.

The seam debug page shows that no nested conversation were created when navigating to the subprocess page. Your proposal is good to re-use jpdl descriptions but doesn't help me in my case.

It looks like jpdl does not support nested conversations and I will have to ditch this option if I want to use nested convos.

PS: If I don't add the file defining the subprocess in components.xml before the parent pageflow, I get a NullPointerException, it would be nice if Seam handle this more gracefully.

2008-04-01 08:39:41,489 ERROR [org.jbpm.jpdl.xml.JpdlXmlReader] couldn't parse process definition

java.lang.NullPointerException

     at org.jbpm.graph.node.DbSubProcessResolver.findSubProcess(DbSubProcessResolver.java:43)

     at org.jboss.seam.bpm.Jbpm$SeamSubProcessResolver.findSubProcess(Jbpm.java:332)

     at org.jbpm.graph.node.ProcessState.read(ProcessState.java:108)

     at org.jbpm.jpdl.xml.JpdlXmlReader.readNodes(JpdlXmlReader.java:260)

     at org.jboss.seam.bpm.PageflowParser.readNodes(PageflowParser.java:41)

     at org.jbpm.jpdl.xml.JpdlXmlReader.readProcessDefinition(JpdlXmlReader.java:156)

     at org.jboss.seam.bpm.Jbpm.parseInputSource(Jbpm.java:317)

     at org.jboss.seam.bpm.Jbpm.getPageflowDefinitionFromResource(Jbpm.java:155)

     at org.jboss.seam.bpm.Jbpm.installPageflowDefinitions(Jbpm.java:235)

     at org.jboss.seam.bpm.Jbpm.startup(Jbpm.java:73)

     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)

     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)

     at java.lang.reflect.Method.invoke(Method.java:585)

     at org.jboss.seam.util.Reflections.invoke(Reflections.java:21)

     at org.jboss.seam.util.Reflections.invokeAndWrap(Reflections.java:125)

     at org.jboss.seam.Component.callComponentMethod(Component.java:2082)

     at org.jboss.seam.Component.callCreateMethod(Component.java:2005)

     at org.jboss.seam.Component.newInstance(Component.java:1976)

     at org.jboss.seam.contexts.Contexts.startup(Contexts.java:304)

     at org.jboss.seam.contexts.Contexts.startup(Contexts.java:278)

     at org.jboss.seam.contexts.ServletLifecycle.endInitialization(ServletLifecycle.java:95)

     at org.jboss.seam.init.Initialization.init(Initialization.java:583)

     at org.jboss.seam.servlet.SeamListener.contextInitialized(SeamListener.java:34)

     at org.apache.catalina.core.StandardContext.listenerStart(StandardContext.java:3856)

     at org.apache.catalina.core.StandardContext.start(StandardContext.java:4361)

     at org.apache.catalina.core.ContainerBase.addChildInternal(ContainerBase.java:790)

     at org.apache.catalina.core.ContainerBase.addChild(ContainerBase.java:770)

     at org.apache.catalina.core.StandardHost.addChild(StandardHost.java:553)

[barbacena]

Subprocess is not the same as nesting. Its more like a include!
We need a way to nest! It could be a parameter in the subprocess node like:

<sub-process name="editCountry" nest="true" />

or

<sub-process name="editCountry" propagation="nest" />

[pmuir]

Make sure there is a feature request in JIRA.

[barbacena]

Created:

JBSEAM-2854

[lexsoto]

Marcell:

I have this same problem.  Have you found a workaround ?
I've been trying to explicity begin and end a nested conversation for the sub process. I'm able to begin the nested conversation when transiting to the subprocess but unable to end the conversation when the subprocess ends.

java.lang.IllegalStateException: pageflow is not currently at a <page> or <start-page> node (note that pageflows that begin during the RENDER_RESPONSE phase should use <start-page> instead of <start-state>)

     org.jboss.seam.pageflow.Pageflow.getPage(Pageflow.java:227)

     org.jboss.seam.pageflow.Pageflow.navigate(Pageflow.java:237)

     org.jboss.seam.pageflow.Pageflow.navigate(Pageflow.java:337)

     org.jboss.seam.jsf.SeamNavigationHandler.handleNavigation(SeamNavigationHandler.java:40)

     com.sun.faces.application.ActionListenerImpl.processAction(ActionListenerImpl.java:119)

     javax.faces.component.UICommand.broadcast(UICommand.java:383)

     javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:447)

     javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:752)

     com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:97)

     com.sun.faces.lifecycle.LifecycleImpl.phase(LifecycleImpl.java:251)

     com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:117)

     javax.faces.webapp.FacesServlet.service(FacesServlet.java:244)

     org.jboss.web.tomcat.filters.ReplyHeaderFilter.doFilter(ReplyHeaderFilter.java:96)

Any help will be appreciated.

Thanks,

-Alex

[gjeudy]

Alex, good luck in trying a workaround. If I were you I would not try to implement something that is not officially supported by Seam.

As you can see a feature request JBSEAM-2854 is already entered, you should vote for it to increase the likelihood that it will be implemented in a future release.

Regards,
-Guillaume

[barbacena]

Alex,

I switched to JSF page navigation for the time being waiting JBSEAM-2854 be implemented. Please vote the issue.

p.s.: curiosity, how did you nest the conversation?

[lexsoto]

Thank you Guillaume and Marcell.

I've now voted for the issue.

-Alex

[marcincaban]

I had gone one step future.
IllegalStateException could be omnited, when no "pageflow" attribute is used with "@Begin" annotation.
I've got another problem - transitions from nested pageflow does not work after starting a nested conversation.
        <page name="xxx" view-id="/aaa.xhtml" redirect="true">
                <transition name="ssss" to="end">
                        <action expression="#{qqqq.wwww()}" />
                </transition>
        </page>

[marcincaban]

15:37:31,546 DEBUG [lifecycle] Entering InvokeApplicationsPhase

15:37:31,546 DEBUG [application] processAction(ffffffffffffButton)

15:37:31,546 DEBUG [application] "JSF1013: Unable to find matching navigation case from view ID '/aaa.xhtml' for outcome 'ssss' and action 'ssss'

15:37:31,546 DEBUG [lifecycle] Exiting InvokeApplicationsPhase

[pkayjava]

i am replying to this error,
PS: If I don't add the file defining the subprocess in components.xml before the parent pageflow, I get a NullPointerException, it would be nice if Seam handle this more gracefully.

Please add page flow definition in components.xml by logical order

                <bpm:pageflow-definitions>
                        <value><![CDATA[sub_page_process_state.jpdl.xml]]></value>
                        <value><![CDATA[main_page_flow.jpdl.xml]]></value>
                </bpm:pageflow-definitions>

I hope, it will work in ur case,

because i am also get this null pointer exception error,
and i went and re order it, and it works.

[pkayjava]

i am replying to this error, PS: If I don't add the file defining the subprocess in components.xml before the parent pageflow, I get a NullPointerException, it would be nice if Seam handle this more gracefully.

Please add page flow definition in components.xml by logical order

                <bpm:pageflow-definitions>
                        <value><![CDATA[sub_page_process_state.jpdl.xml]]></value>
                        <value><![CDATA[main_page_flow.jpdl.xml]]></value>
                </bpm:pageflow-definitions>

I hope, it will work in ur case,

because i am also get this null pointer exception error, and i went and re order it, and it works.