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Re: Events and States (was: timeouts & states (was: Abstract Bind able Choreography))

From: Assaf Arkin <arkin@intalio.com>
Date: Thu, 10 Apr 2003 16:16:51 -0700
Message-ID: <3E95FB63.80105@intalio.com>
To: "Burdett, David" <david.burdett@commerceone.com>
CC: "'jdart@tibco.com'" <jdart@tibco.com>, Cummins Fred A <fred.cummins@eds.com>, public-ws-chor@w3.org



Burdett, David wrote:

> >>>Very good questions. But what do you want (or perhaps more 
> importantly,
> need) it to do? As you say, a state machine is really a mechanism. What
> is the functional requirement?<<<
> I would put the functional requirements for which state machines are a 
> possible answer as follows:
> "An implementation of a process that is following a choreography MUST 
> be able to verify that the choreography is being followed correctly as 
> specified in the choreography definition."
> I would then have two further more closely defined but related 
> requirements of the products of this group ...
> "A choreography definition should be usable at Design Time to validate 
> that a process should be capable of carrying out a choreography 
> correctly as specified."
> "A choreography definition shoule be usable at Run Time to validate 
> that a process is executing a choreography correctly as specified".
> ... and finally one more ...
> "If a process detects that a choreography is not being followed 
> correctly, then the process SHOULD be able to use the choreography 
> definition to identify exactly what went wrong."
> This last one means that you stand a better chance of being able to 
> fix the problem when it occurs.
> Thoughts?
> David
> -----Original Message-----
> From: Jon Dart [mailto:jdart@tibco.com]
> Sent: Thursday, April 10, 2003 2:56 PM
> To: Cummins Fred A
> Cc: public-ws-chor@w3.org
> Subject: Re: Events and States (was: timeouts & states (was: Abstract
> Bindable Choreography))
> Cummins, Fred A wrote:
> > This raises questions about the scope of a choreography.  When does
> > it end?  When a disconnect occurs?  When a particular business
> > transaction is completed?  When a relationship is terminated?
> > Maybe any of the above?
> >
> > Do the state machines provide the mechanism for nesting of component
> > choreographies?
> Very good questions. But what do you want (or perhaps more importantly,
> need) it to do? As you say, a state machine is really a mechanism. What
> is the functional requirement?
> At minimum, I would guess it is the ability to transition to a distinct
> state when a timeout occurs. This state could be the termination of the
> choreography (implying no more processing will occur). Or it could be an
> error state (implying there might be some warning given, or some
> recovery effort made, e.g. a retry - this assumes you are doing this at
> the application level and not in some lower-level reliable messaging
> protocol). Certainly I can think of real-world examples where you'd need
> this functionality. This is something of a simplification of earlier
> proposals. If we need something more complex, I'd like to see some
> rationale behind it.
> --Jon

"Those who can, do; those who can't, make screenshots"

Assaf Arkin                                          arkin@intalio.com
Intalio Inc.                                           www.intalio.com
The Business Process Management Company                 (650) 577 4700

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Received on Thursday, 10 April 2003 19:18:16 UTC

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