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Re: message exchange patterns and # of parties

From: David Booth <dbooth@w3.org>
Date: Thu, 11 Sep 2003 16:32:16 -0400
Message-Id: <>
To: Sanjiva Weerawarana <sanjiva@watson.ibm.com>
Cc: www-ws-desc@w3.org, "Amelia A. Lewis" <alewis@tibco.com>

See comment below.

At 02:25 PM 9/11/2003 -0400, Amelia A. Lewis wrote:
>On Thu, 11 Sep 2003 23:38:24 +0600
>Sanjiva Weerawarana <sanjiva@watson.ibm.com> wrote:
>. . .
> > Amy, I'm confused about your comment ref multicast- are you suggesting
> > that the pattern framework is deficient in some form w.r.t. being able
> > to capture multicast patterns? If so please suggest what needs to be
> > changed; IMO our objective is and should be to define a framework
> > rich enough to capture patterns including multicast ones.
>. . .  Our final resolution proposed that unless the
>information was important to both sides of a message being exchanged, then 
>it wasn't to be represented in the pattern.

Yes, the other reason the Patterns TF thought that the current patterns are 
adequate for use also in multicast situations is that the client and 
service are not limited to all and only those messages that are indicated 
in the pattern.  One of the Pattern Task Force recommendations explains this:

Recommendation: Patterns Specify *Minimal* Behavior

Each pattern represents a contract that specifies *minimal* behavior that 
is expected between the parties. . . .

The clients and services may have additional behaviors that are not 
specified by the pattern. Specifically, a client or service may send other 
messages (to each other or other parties) that are not described by the 
pattern. However, in such case, the parties must use other means to agree 
on the handling of the additional messages. For example, a message 
specified in a pattern as being from service S to client A might actually 
be broadcast to other clients in addition to being sent to client A. 
However, the pattern only governs the agreement to send the message to 
client A.

David Booth
W3C Fellow / Hewlett-Packard
Telephone: +1.617.253.1273
Received on Thursday, 11 September 2003 16:32:18 UTC

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