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Re: Relationship cardinalities (was ... RE: Requirements: Decisio n Po ints Requirement Proposals

From: Assaf Arkin <arkin@intalio.com>
Date: Mon, 09 Jun 2003 14:49:09 -0700
Message-ID: <3EE500D5.40104@intalio.com>
To: "Burdett, David" <david.burdett@commerceone.com>
CC: "'Martin Chapman'" <martin.chapman@oracle.com>, "'Jean-Jacques Dubray'" <jjd@eigner.com>, "'Yaron Y. Goland'" <ygoland@bea.com>, "'WS Chor Public'" <public-ws-chor@w3.org>

Burdett, David wrote:

>     [David Burdett] Not sure. For example if you design four different
>     choreographies that are alternative ways of doing the same thing
>     (e.g. placing an order), wouldn't the role stay the same?
>
I need to see something more concrete here to understand what it means 
to stay the same role. What would make a role the same across two 
choreographies?

arkin

>     At most the relationship between choreographies will be akin to a
>     type library that gets used in multiple progams.
>     [David Burdett] Agreed. 
>      
>     Martin.
>      
>      
>
>         -----Original Message-----
>         *From:* public-ws-chor-request@w3.org
>         [mailto:public-ws-chor-request@w3.org]*On Behalf Of *Burdett,
>         David
>         *Sent:* Monday, June 09, 2003 1:35 PM
>         *To:* 'Assaf Arkin'; Burdett, David
>         *Cc:* 'Jean-Jacques Dubray'; 'Yaron Y. Goland'; 'WS Chor Public'
>         *Subject:* RE: Relationship cardinalities (was ... RE:
>         Requirements: Decisio n Po ints Requirement Proposals
>
>         Assaf
>
>         I always tend to think that one role can take part in multiple
>         choreographies, for example a buyer could take part in:
>         1. Several different choreographies each of which resulted in
>         the placement of an order
>         2. A separate order status choreography that could work with
>         any of the different choreographies.
>
>         I also recognize that the same choreography and roles could be
>         invented multiple times. For example, the shoe industry could
>         invent a choreography for placing orders that was identical to
>         one developed by the wine industry but they give the
>         choroegraphies different identifiers (URIs) for choreography
>         itself and each of its roles.
>
>         This is really a broader standardization issue that will only
>         be solved when there is choreography instance standardization.
>         For example the UBL initiative is developing standard
>         representations and semantics for order documents using XML
>         schema. We really need standard order placement choreographies
>         to be developed using WS-Chor ... but we need WS-Chor first.
>
>         David
>
>
>         -----Original Message-----
>         From: Assaf Arkin [mailto:arkin@intalio.com]
>         Sent: Monday, June 09, 2003 12:18 PM
>         To: Burdett, David
>         Cc: 'Jean-Jacques Dubray'; 'Yaron Y. Goland'; 'WS Chor Public'
>         Subject: Re: Relationship cardinalities (was ... RE:
>         Requirements:
>         Decision Po ints Requirement Proposals
>
>
>         For brevity sake, two comments and +1 on everything else.
>
>         Burdett, David wrote:
>
>         >CHOREOGRAPHY RELATED
>         >1. A role may take part in one or more choreographies
>         >For example a buyer there are several different ways of
>         placing orders that
>         >involve different sequences of messages. However the basic
>         role stays the
>         >same.
>         > 
>         >
>         That depends on how you define a role. You can define a role
>         as being a
>         component of the choreography in which case a role
>         participants in one
>         choreography. That does not restrict an entity from being
>         multiple roles
>         in multiple choreographies. You can define roles that
>         participate in any
>         number of choreographies, but I'm not sure what it buys you,
>         and if
>         you're having problems reaching agreements you probably would
>         have a
>         problem agreeing to use the same role in multiple choreographies.
>         (Again, won't restrict the same entity ...)
>
>         I accept that as a party intending to buy products I would
>         assume the
>         role 'buyer' in one choreography, 'procurer' in another, and
>         'sucker' in
>         a third one. On the other hand, I may be expected to operate
>         in the same
>         way in all three choreographies, i.e. implement the same
>         interface, but
>         that brings us back to the role=interface equality, mobile
>         process model
>         and all other undesirable solutions.
>
>         >4. A choreography specifies the sequence, conditions and
>         dependencies of
>         >sending one or more messages
>         >This is really the core of what choreographies are all about.
>         The only
>         >question I would have is whether this is compatible with the
>         ideas of
>         >pi-calculus, and if it isn't does it matter?
>         > 
>         >
>         Yes it does. And if it doesn't then pi-calculus wouldn't be
>         relevent to
>         our work.
>
>
>         arkin
>


-- 
"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 Monday, 9 June 2003 17:49:50 GMT

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