Planning to remove @Begin(id=..)? Help Needed!
Hi all,
reading comments to JBSEAM-976 (http://jira.jboss.com/jira/browse/JBSEAM-976) I read this:
Gavin King [20/Mar/07 08:27 PM]
Anyway, now that we have the now < conversation > stuff in pages.xml, we should deprecate @Begin(id=....).
I had a look both at the current documentation and software provided (1.2.0PATCH1) and the roadmap to SEAM 1.3.0BETA1 and I did not find any (but if I'm wrong please tell me how) other thing which makes available such feature (<conversation-begin> seems not to support the id parameter and I did not find other stuff related to the pages.xml to handle it).
Gavin King [20/Mar/07 08:27 PM]
Right, its not a bug. You should not expect @Begin(join=true, id="#{..}") to do anything if there is an existing long-running conversation. That would be totally evil. You would be switching from one LRC to another.
What can I say.. Yes, I would be (and I can with the current Seam code) switching from one LRC to another, and I do not understand why this is evil, indeed, the conversation management of Seam actually detects for me if the user asks for a service he asked for before and automatically resumes the correct conversation and it's data. I cannot base my app on pageflow or navigation rules because I'm trying to provide a set of services to the end user collected in the same *workspace*.
The workspace loads the modules at compile time through a configuration file and some rules, e.g. interfaces, the modules have to adhere to be plugged in the workspace, each module lives in its conversation; the navigation rules are trivial: when a user asks for a service.. do it (display the page -> open a tab.. the workspace looks like a desktop app (everything *se(a)ems* :) to be in the same page) with a list of the services available on the left and a working area on the right, arranged as a tabbed view to allow a fast switch between a service and another).
A service can have more than one instance (same service in more than a tab), this means that I have the same outcome, the same view-id but not the same conversation id.
Each service *needs* a top level long running conversation and cannot work with nested ones because the user can close a tab (end a conversation) and I need a way to remove a conversation without removing all the other conversations nested in it (because if a user asks for the remotion of one service he does not.. and all the others I opened after it).
Is this that evil? And if, why?
Now I would like to say something about the JBSEAM-976 rejection.
Shane Bryzak [20/Mar/07 08:14 PM]
The submitted test case does not start a new conversation. Besides, this feature is going to become deprecated in favour of the new natural conversation ids feature.
If you say from the second call to the @Begin method.. yes, it's true, but it's not the reason of the submitted issue, indeed, from doc's 6.6:
Clearly, these example result in the same conversation id every time a particular hotel, blog or task is selected.
So what happens if a conversation with the same conversation id already exists when the new conversation begins?
<b>Well, Seam detects the existing conversation and redirects to that conversation without running the
@Begin method again.</b> This feature helps control the number of workspaces that are created when using workspace
management.
then I expect that the @Begin method will no more called after the first time (for the same conversation id), but since the 1.1.1GA it does.
I made some tests on it modifying a little the test case: I added another action and a "catchall" action in the pages.xml
<pages>
<page view-id="/*" action="#{sessionHandler.checkConversation}"></page>
</pages>
the checkConversation is trivial.. prints on the server the conversation status
public String checkConversation() {
String result = null;
Logger.getLogger(this.getClass()).info("<CHECK CONVERSATION> IS THERE A LONG RUNNING CONVERSATION: " + (Conversation.instance().isLongRunning() ? "YES" : "NO"));
Logger.getLogger(this.getClass()).info("<CHECK CONVERSATION> IS THERE A NESTED CONVERSATION: " + (Conversation.instance().isNested() ? "YES" : "NO"));
Logger.getLogger(this.getClass()).info("<CHECK CONVERSATION> LONG RUNNING CONVERSATION ID IS: " + Conversation.instance().getId());
Logger.getLogger(this.getClass()).info("<CHECK CONVERSATION> LONG RUNNING CONVERSATION VIEW ID IS: " + Conversation.instance().getViewId());
Logger.getLogger(this.getClass()).info("<CHECK CONVERSATION> LONG RUNNING CONVERSATION DESCRIPTION IS: " + Conversation.instance().getDescription());
return result;
}
and I checked the behaviour, these are the results:
when the app starts the catchall method prints out this:
2007-03-27 10:56:13,868 INFO [org.jboss.seam.contexts.Lifecycle] starting up: org.jboss.seam.security.identity 2007-03-27 10:56:13,918 INFO [org.jboss.seam.core.Pages] reading pages.xml 2007-03-27 10:56:14,376 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> IS THERE A LONG RUNNING CONVERSATION: NO 2007-03-27 10:56:14,376 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> IS THERE A NESTED CONVERSATION: NO 2007-03-27 10:56:14,376 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> LONG RUNNING CONVERSATION ID IS: 1 2007-03-27 10:56:14,378 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> LONG RUNNING CONVERSATION VIEW ID IS: null 2007-03-27 10:56:14,379 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> LONG RUNNING CONVERSATION DESCRIPTION IS: null
as expected a temporary conversation is created with id 1 and will not be promoted because there's no conversation to begin.
Case 1 - @Begin(id=#{param.conversationId})
This should cover the case described in the documentation:
Clearly, these example result in the same conversation id every time a particular hotel, blog or task is selected.
<b>So what happens if a conversation with the same conversation id already exists when the new conversation begins?</b>
Well, Seam detects the existing conversation and redirects to that conversation without running the
@Begin method again. This feature helps control the number of workspaces that are created when using workspace
management.
I read, but maybe I'm wrong, when the @Begin method is called more than once on the same id, Seam catches this situation, switches to the long running and does not execute the @Begin method again (but we know that the last is not true), anyway, what happens:
a) I call the @Begin method of the actionone and the catchall (plus the actionone prints) say:
2007-03-27 10:57:14,509 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> IS THERE A LONG RUNNING CONVERSATION: NO 2007-03-27 10:57:14,509 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> IS THERE A NESTED CONVERSATION: NO 2007-03-27 10:57:14,509 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> LONG RUNNING CONVERSATION ID IS: 2 2007-03-27 10:57:14,509 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> LONG RUNNING CONVERSATION VIEW ID IS: null 2007-03-27 10:57:14,509 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> LONG RUNNING CONVERSATION DESCRIPTION IS: null 2007-03-27 10:57:14,558 INFO [it.seam.testcase.ActionOne] <ACTIONONE> START CONVERSATION METHOD CALLED 2007-03-27 10:57:14,558 INFO [it.seam.testcase.ActionOne] <START CONVERSATION> IS THERE A LONG RUNNING CONVERSATION: NO 2007-03-27 10:57:14,558 INFO [it.seam.testcase.ActionOne] <START CONVERSATION> IS THERE A NESTED CONVERSATION: NO 2007-03-27 10:57:14,558 INFO [it.seam.testcase.ActionOne] <START CONVERSATION> LONG RUNNING CONVERSATION ID IS: actionone 2007-03-27 10:57:14,558 INFO [it.seam.testcase.ActionOne] <START CONVERSATION> LONG RUNNING CONVERSATION VIEW ID IS: null 2007-03-27 10:57:14,558 INFO [it.seam.testcase.ActionOne] <START CONVERSATION> LONG RUNNING CONVERSATION DESCRIPTION IS: null
Creating the temporary conversation with id actionone which will be promoted to a long running because we are starting a conversation
b) I call the @Begin method of the actionone again and the catchall says:
2007-03-27 10:57:39,699 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> IS THERE A LONG RUNNING CONVERSATION: YES 2007-03-27 10:57:39,699 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> IS THERE A NESTED CONVERSATION: NO 2007-03-27 10:57:39,699 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> LONG RUNNING CONVERSATION ID IS: actionone 2007-03-27 10:57:39,699 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> LONG RUNNING CONVERSATION VIEW ID IS: /actionone.xhtml 2007-03-27 10:57:39,699 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> LONG RUNNING CONVERSATION DESCRIPTION IS: null
great found and handled but...
2007-03-27 10:45:45,441 DEBUG [org.jboss.seam.Component] done initializing: org.jboss.seam.core.events
2007-03-27 10:45:45,441 DEBUG [org.jboss.seam.core.Events] Processing event:org.jboss.seam.postSetVariable.actionOne
2007-03-27 10:45:45,442 ERROR [org.jboss.seam.jsf.SeamPhaseListener] uncaught exception
javax.faces.el.EvaluationException: Exception while invoking expression #{actionOne.startConversation}
at org.apache.myfaces.el.MethodBindingImpl.invoke(MethodBindingImpl.java:153)
at org.jboss.seam.actionparam.ActionParamBindingHelper.invokeTheExpression(ActionParamBindingHelper.java:58)
at org.jboss.seam.actionparam.ActionParamMethodBinding.invoke(ActionParamMethodBinding.java:75)
at org.jboss.seam.core.Expressions$2.invoke(Expressions.java:106)
at org.jboss.seam.core.Pages.callAction(Pages.java:466)
at org.jboss.seam.core.Pages.enterPage(Pages.java:275)
....
Caused by: java.lang.IllegalStateException: begin method invoked from a long running conversation, try using @Begin(join=true) on method: start
Conversation
at org.jboss.seam.interceptors.ConversationInterceptor.aroundInvoke(ConversationInterceptor.java:45)
at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:69)
at org.jboss.seam.interceptors.MethodContextInterceptor.aroundInvoke(MethodContextInterceptor.java:27)
at org.jboss.seam.intercept.SeamInvocationContext.proceed(SeamInvocationContext.java:69)
The programmer did not specify to join them and they did not join.. debug window, then, either I did not understand what's written in 6.6 or the doc is not complete because it does not work without a join.
Case 2 - @Begin(join=true, id=#{param.conversationId})
a) I call the @Begin method of the actionone and the catchall (plus the actionone prints) say:
007-03-27 10:49:08,939 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> IS THERE A LONG RUNNING CONVERSATION: NO 007-03-27 10:49:08,939 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> IS THERE A NESTED CONVERSATION: NO 007-03-27 10:49:08,939 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> LONG RUNNING CONVERSATION ID IS: 2 007-03-27 10:49:08,939 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> LONG RUNNING CONVERSATION VIEW ID IS: null 007-03-27 10:49:08,939 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> LONG RUNNING CONVERSATION DESCRIPTION IS: null 007-03-27 10:49:08,991 INFO [it.seam.testcase.ActionOne] <ACTIONONE> START CONVERSATION METHOD CALLED 007-03-27 10:49:08,992 INFO [it.seam.testcase.ActionOne] <START CONVERSATION> IS THERE A LONG RUNNING CONVERSATION: NO 007-03-27 10:49:08,992 INFO [it.seam.testcase.ActionOne] <START CONVERSATION> IS THERE A NESTED CONVERSATION: NO 007-03-27 10:49:08,992 INFO [it.seam.testcase.ActionOne] <START CONVERSATION> LONG RUNNING CONVERSATION ID IS: actionone 007-03-27 10:49:08,992 INFO [it.seam.testcase.ActionOne] <START CONVERSATION> LONG RUNNING CONVERSATION VIEW ID IS: null 007-03-27 10:49:08,992 INFO [it.seam.testcase.ActionOne] <START CONVERSATION> LONG RUNNING CONVERSATION DESCRIPTION IS: null
Creating the temporary conversation with id actionone which will be promoted to a long running because we are starting a conversation.
b) I call the @Begin method of the actiontwo and the catchall (plus the actiontwo prints) say:
007-03-27 10:49:19,257 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> IS THERE A LONG RUNNING CONVERSATION: NO 007-03-27 10:49:19,257 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> IS THERE A NESTED CONVERSATION: NO 007-03-27 10:49:19,257 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> LONG RUNNING CONVERSATION ID IS: 3 n007-03-27 10:49:19,257 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> LONG RUNNING CONVERSATION VIEW ID IS: null 007-03-27 10:49:19,257 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> LONG RUNNING CONVERSATION DESCRIPTION IS: null 007-03-27 10:49:19,279 INFO [it.seam.testcase.ActionTwo] <ACTIONTWO> START CONVERSATION METHOD CALLED 007-03-27 10:49:19,279 INFO [it.seam.testcase.ActionTwo] <START CONVERSATION> IS THERE A LONG RUNNING CONVERSATION: NO 007-03-27 10:49:19,279 INFO [it.seam.testcase.ActionTwo] <START CONVERSATION> IS THERE A NESTED CONVERSATION: NO 007-03-27 10:49:19,279 INFO [it.seam.testcase.ActionTwo] <START CONVERSATION> LONG RUNNING CONVERSATION ID IS: actiontwo 007-03-27 10:49:19,279 INFO [it.seam.testcase.ActionTwo] <START CONVERSATION> LONG RUNNING CONVERSATION VIEW ID IS: null 007-03-27 10:49:19,279 INFO [it.seam.testcase.ActionTwo] <START CONVERSATION> LONG RUNNING CONVERSATION DESCRIPTION IS: null
Creating the temporary conversation with id actiontwo which will be promoted to a long running because we are starting a conversation.
c) I call the @Begin method of the actionone again and the catchall (plus the actionone prints) say:
007-03-27 10:49:27,811 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> IS THERE A LONG RUNNING CONVERSATION: YES 007-03-27 10:49:27,811 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> IS THERE A NESTED CONVERSATION: NO 007-03-27 10:49:27,811 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> LONG RUNNING CONVERSATION ID IS: actionone 007-03-27 10:49:27,811 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> LONG RUNNING CONVERSATION VIEW ID IS: /actionone.xhtml 007-03-27 10:49:27,811 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> LONG RUNNING CONVERSATION DESCRIPTION IS: null 007-03-27 10:49:27,812 INFO [it.seam.testcase.ActionOne] <ACTIONONE> START CONVERSATION METHOD CALLED 007-03-27 10:49:27,812 INFO [it.seam.testcase.ActionOne] <START CONVERSATION> IS THERE A LONG RUNNING CONVERSATION: YES 007-03-27 10:49:27,812 INFO [it.seam.testcase.ActionOne] <START CONVERSATION> IS THERE A NESTED CONVERSATION: NO 007-03-27 10:49:27,812 INFO [it.seam.testcase.ActionOne] <START CONVERSATION> LONG RUNNING CONVERSATION ID IS: actionone 007-03-27 10:49:27,812 INFO [it.seam.testcase.ActionOne] <START CONVERSATION> LONG RUNNING CONVERSATION VIEW ID IS: /actionone.xhtml 007-03-27 10:49:27,812 INFO [it.seam.testcase.ActionOne] <START CONVERSATION> LONG RUNNING CONVERSATION DESCRIPTION IS: null
Found actionone conversation and switched to (everything handled).
d) I call the @Begin method of the actiontwo again and the catchall (plus the actiontwo prints) say:
007-03-27 10:49:38,523 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> IS THERE A LONG RUNNING CONVERSATION: YES 007-03-27 10:49:38,523 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> IS THERE A NESTED CONVERSATION: NO 007-03-27 10:49:38,523 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> LONG RUNNING CONVERSATION ID IS: actiontwo 007-03-27 10:49:38,523 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> LONG RUNNING CONVERSATION VIEW ID IS: /actiontwo.xhtml 007-03-27 10:49:38,523 INFO [it.seam.testcase.SessionHandler] <CHECK CONVERSATION> LONG RUNNING CONVERSATION DESCRIPTION IS: null 007-03-27 10:49:38,523 INFO [it.seam.testcase.ActionTwo] <ACTIONTWO> START CONVERSATION METHOD CALLED 007-03-27 10:49:38,523 INFO [it.seam.testcase.ActionTwo] <START CONVERSATION> IS THERE A LONG RUNNING CONVERSATION: YES 007-03-27 10:49:38,523 INFO [it.seam.testcase.ActionTwo] <START CONVERSATION> IS THERE A NESTED CONVERSATION: NO 007-03-27 10:49:38,523 INFO [it.seam.testcase.ActionTwo] <START CONVERSATION> LONG RUNNING CONVERSATION ID IS: actiontwo 007-03-27 10:49:38,523 INFO [it.seam.testcase.ActionTwo] <START CONVERSATION> LONG RUNNING CONVERSATION VIEW ID IS: /actiontwo.xhtml 007-03-27 10:49:38,523 INFO [it.seam.testcase.ActionTwo] <START CONVERSATION> LONG RUNNING CONVERSATION DESCRIPTION IS: null
Found actiontwo conversation and switched to (everything handled).
Everything seems to work properly except the reason of the issue JBSEAM-976, indeed the @Begin method is called more than once.
I tried also without ids in the @Begin, this causes the creation of a brand new conversation for every call to the @Begin method, but this is not enough for the app I'm building.
I don't know if you plan to remove the join=true related to a @Begin(id=...) but please don't remove the explicit id facility, we wrote a lot of code based on this and the remotion causes the loss of a huge amount of time.
Regards,
Raffaele Camanzo
