Re: Resetting state of service references at conversation end

Mon, 10 Sep 2007 17:05:56 -0700 

Hi,
As we agreed, the conversation id alone is not sufficient to deal with conversations. We need to maintain the state of the conversations (STARTED, ENDED or EXPIRED). 

I propose that we do the following:

1) Define a ConversationManager like:

public interface ConversationManager() {

   String start(String conversationID);  // If the conversationID is null, 
the system will generate one. Returns the conversation ID

   void end(String conversationID);  // Ends the conversation

   ConversationState getConversationState(String conversationID); // Get 
the state of the conversation

   void register(ConversationListener listener); // Register a listener
   void unregister(ConversationListener listener); // Remove a listener
}

public interface ConversationListener() {
   void conversationStarted(String conversationID);
   void conversationEnded(String conversationID);
   void conversationExpired(String conversationID);
}

public enum ConversationState {
   STARTED, ENDED, EXPIRED
}


2) The proxy or callable references will only keep the conversation ID. 
Whenever the Conversation object is referenced or we need to perform any 
actions to a conversation, we use the ID to look up the state of the 
conversation.



3) Move the expiration timer from the ConversationScopeContainer to the 
ConversationManager.



4) The ConversationScopeContainer will be registered as listener to the 
ConversationManager. When an active conversation is started, expired or 
ended, the ConversationScopeContainer will be notified.



5) The ConversationManager maintains the conversations using an in-memory 
Map as the first step. In the future, it can be extended to backed by a 
persistent store.


Thanks,
Raymond


----- Original Message ----- 
From: "Simon Laws" <[EMAIL PROTECTED]>

To: <tuscany-dev@ws.apache.org>
Sent: Sunday, September 09, 2007 11:10 AM
Subject: Re: Resetting state of service references at conversation end



Hi Raymond

some comments below...

Simon

On 9/9/07, Raymond Feng <[EMAIL PROTECTED]> wrote:


Hi,


I have been thinking of this problem as well. It's not realistic to 
search

for all CallableReferences because it can be dynamically created too. We




Agreed. You would have to have registered them somewhere first. This is 
what

happens in the case of the conversation scope container currently.


probably need to use a listener pattern to have all the Conversation 
objects

listen on the events of expiration or end of the conversation and reset
the
state based on the event. Another way is to have a pointer to the



This would rely on having the conversation object register with something
that is able to broadcast these events. Where would be a sensible place to
put this event broadcasting function. Do we have an internal eventing
feature? Scope container?

ScopeContainer in the ConversationImpl object and query the state of the

conversation before it's used.



This would still involve updating the scope containers to record the
conversation status against conversation id. But maybe this is an easier
generic change. I.e. instigate a collection at the abstract level that
allows conversationIds to be assoicated with the conversation object that
created them.

You could just store the conversation state and allow the conversation to
ask for it as you suggest. Not clear to me what this buys though.

By the current design, the ConversationScopeContainer is per component to

keep implementation instances by conversation id. So when the same
conversation involves two components, there are two
ConversationScopeContainer instances.



I think this design is sound. The missing link for us it so be able to
access a conversation object given conversationId during callback at the
client end.

Thanks,

Raymond

----- Original Message -----
From: "Simon Laws" <[EMAIL PROTECTED]>
To: "tuscany-dev" <tuscany-dev@ws.apache.org>
Sent: Sunday, September 09, 2007 4:15 AM
Subject: Resetting state of service references at conversation end


> When @ConversationEnd is called on a satefull callback the conversation
id
> of the client reference is not reset back to null. I have put a fix in
in
> the case where the scope of the originating component is CONVERSATION.
> This
> relies on storing the Conversation object in the conversational scope
> container so that when the instance is marked for removal the
conversation
> id can be set to null also.
>
> However to make this approach work for all scopes I have to go and add
> this

> feature to the other scope containers. Before I do this is there an 
> easy

> way
> to get to all of a component instances CallableReferences from the
> JavaImplementationInvoker? If there were I could search for the
> conversation

> object with the matching conversationId rather than adding extra code 
> to

> store it away.
>
> Simon
>


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