conversation-required: its purpose and its name are not related

[luxspes]

The bug JBSEAM-3480 was marked to day as Won't Fix and I am posting here to start a discussion trying to make its spirit reincarnate:

Shane Bryzak wrote in JIRA:



I've spent a bit of time playing with the test case, and it seems to be working as expected. I think there might be some misunderstanding as to the semantics of the conversation-required attribute in pages.xml, which we are to blame for as it is not clearly documented (I'll raise a separate issue to address this for next release). When a page is marked with conversation-required="true", it means that a previously started conversation must be propagated when that view is restored. This all happens in the RESTORE_VIEW phase, which is too early to know that you'll be calling a @Begin method in the INVOKE_APPLICATION phase.

Based on Shane Bryzak  comment I now think that conversation-required does not do what its name say (prevent access to a page if a conversation is not active), of course it is inaccurate in many ways, so I propose the following:

Deprecate the conversation-required="true" option, because it is not to prevent access to a page if a long running conversation is not active, it is to prevent access to a page if a previously started conversation has not been propagated when that view is restored. I really do not get when would we want to do that, but that is what it is for. I do think a new name that is a better fit to what it does should be chosen for it, but I couldn't think of a good one.

We should have a new long-running-conversation-required="true" (I chose that number trusting that JBSEAM-3484, will be solved, if it is not, the accurate name would look funny: long-or-nested-running-conversation-required="true")  that does what we as users of the framework expect: prevent access to a page if a long conversation/nested conversation is not active. I think that new option should be as shortcut for this code:

<page xmlns="http://jboss.com/products/seam/pages"
      xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
      xsi:schemaLocation="http://jboss.com/products/seam/pages http://jboss.com/products/seam/pages-2.0.xsd"
      no-conversation-view-id="/Blank.xhtml" conversation-required="false">
      
   <action execute="#{categoryList.checkConversationRequired}"/>
           
   <navigation from-action="#{categoryList.checkConversationRequired}">
   <rule if-outcome="forbidden">
    <redirect view-id="/NoConversation.xhtml">
    </redirect>
   </rule>
   </navigation>

</page>


public String checkConversationRequired(){
  Conversation conversation = Conversation.instance();
  if(conversation.isLongRunning() || conversation.isNested())
     return "ok";
  return "forbidden";
} 

So... since JBSEAM-3480 is marked as Won't Fix  should I create a new JIRA asking for long-running-conversation-required  as a new feature?

[shane.bryzak]

Please raise a new JIRA issue, and we'll try to get a discussion going on seam-dev to determine how to proceed with this.

[luxspes]

One thing about conversation-required="true" still puzzles me, if its verification happens in the RESTORE_VIEW phase, which is too early to know that you'll be calling a @Begin method in the INVOKE_APPLICATION phase then:

Why if I add @Begin to the action it works the first time and if I remove @Begin it denies me access always (including the first time)?

Why it can know that I will  be (or will not be) calling a @Begin method, but only the first time? (and the 3th, the 5th, the 7th and so on and so forth, but forget about that, why does it work the 1st time!?)

[shane.bryzak]

Are you sure there's no conversation ID parameter being passed in the instances where it does work?