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RE: Events and States (was: timeouts & states (was: Abstract Bi ndable Choreography))

From: Cummins, Fred A <fred.cummins@eds.com>
Date: Fri, 11 Apr 2003 18:29:54 -0500
Message-ID: <27C20ED5A6D3D511ADF30002A5D6464802A71AF1@USPLM214>
To: Ricky Ho <riho@cisco.com>, Assaf Arkin <arkin@intalio.com>
Cc: jdart@tibco.com, "Cummins, Fred A" <fred.cummins@eds.com>, public-ws-chor@w3.org

A fundamental issue here is whether the state transition dependencies
between two or more binary exchanges are to be represented in the
choreographies or are private to the participants.

A buyer-seller relationship may proceed to a certain point before the
seller wants to know that the buyer has credit.  The relationship 
between the buyer-seller choreography and the seller-creditor
choreography can be left entirely to the seller to determine, and will
be reflected in the seller's public state transition at a particular 
point in the process.

In designing choreographies, it would be useful to reflect this
linkage so that it is considered where it might impact the efficiency
of the exchange.  That does not mean that it is necessarily expressed 
in the choreography. At the same time, if the lack of credit results
in a transition to a unique state, then it will be reflected in the
choreography, implicitly.  But the event of learning that the buyer
does or does not have credit does not directly affect the choreography.


> -----Original Message-----
> From: Ricky Ho [mailto:riho@cisco.com]
> Sent: Friday, April 11, 2003 1:47 PM
> To: Assaf Arkin
> Cc: jdart@tibco.com; Cummins Fred A; public-ws-chor@w3.org
> Subject: Re: Events and States (was: timeouts & states (was: Abstract
> Bindable Choreography))
> I understand the "nested state", basically you breakdown a 
> state into finer 
> grain, but this is still mutually exclusive.  You can only be 
> at one of the 
> substate.
> In David's example, lets say the seller interact with the 
> manufacturer as 
> well as the credit check.  In the public state diagram, the 
> seller want to 
> express that the purchase order will be confirmed only when 
> the credit 
> check passes as well as the manufacturer have the product in stock.
> So, does the seller has two non-exclusive states "credit-pass", 
> "product-available" ?
> or 4 mutually-exclusive states "credit-pass and product-available", 
> "credit-pass and NOT product-available" .....
> The latter is easier to understand.
> Rgds, Ricky
> At 10:15 AM 4/11/2003 -0700, Assaf Arkin wrote:
> >Ricky Ho wrote:
> >
> >>
> >>In David's example, "State" is not mutually exclusive.  
> (Correct me if 
> >>I'm wrong).  A role can have multiple "states" at the same 
> time and each 
> >>of this state can accept different events and transition to another 
> >>states.  Somewhat similar to a multi-thread scenario.  So 
> when one thread 
> >>reaches an end state.  The choreography can still be active 
> because of 
> >>other threads.
> >>
> >>This is quite different from the traditional state chart 
> who try to avoid 
> >>composite states.  Am I totally lost ?
> >
> >Some state transition models have mutually exclusive states.
> >
> >Statechart diagrams have composite states, so they allow for 
> non-exclusive 
> >states and multiple concurrent sub-states as part of the 
> same parent state.
> >
> >arkin
> >
> >>
> >>Rgds, Ricky
> >
> >
> >
Received on Friday, 11 April 2003 19:30:02 UTC

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