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RE: WSDL and pub/sub

From: Martin Chapman <martin.chapman@oracle.com>
Date: Thu, 12 Feb 2004 20:01:50 -0000
To: "'Ugo Corda'" <UCorda@SeeBeyond.com>, "'Burdett, David'" <david.burdett@commerceone.com>, "'Steve Ross-Talbot'" <steve@enigmatec.net>, "'WS Choreography'" <public-ws-chor@w3.org>
Message-ID: <00bd01c3f1a3$103492b0$0301a8c0@us.oracle.com>
we could of course define some open standards in this space :-) 

-----Original Message-----
From: public-ws-chor-request@w3.org [mailto:public-ws-chor-request@w3.org]
On Behalf Of Ugo Corda
Sent: Thursday, February 12, 2004 6:35 PM
To: Burdett, David; Steve Ross-Talbot; WS Choreography
Subject: RE: WSDL and pub/sub

Does it make sense for us to define the details of a pub/sub mechanism (e.g.
the delivery address representation) when there are already specs like
WS-Eventing and WS-Notification which do that?

-----Original Message-----
From: public-ws-chor-request@w3.org [mailto:public-ws-chor-request@w3.org]
On Behalf Of Burdett, David
Sent: Thursday, February 12, 2004 10:23 AM
To: 'Steve Ross-Talbot'; WS Choreography
Subject: RE: WSDL and pub/sub


Giving this a bit of thought makes me think that the essence of pub-sub is

1. The publisher sets up a service that accepts subscriptions requests and
changes for some other service that actually publishes documents/messages.

2. The subscriber then requests subscription to a service by sending a
messge which then gets either accepted or rejected.

3. When the subscriber makes the request, they must include some kind of
"delivery address" that identifies where documents/messages etc, generated
by the publisher must be sent

4. If the request is accepted, then the publisher will return some kind of
"identifier" for the subscription that can later be used when changing or
cancelling the subscription

5. The publisher starts publishing documents. This is a one-way message
although it might be delivered reliably 
6. The publisher continues publishing documents until: a) the subscription
is cancelled, or b) the subscription runs-out, e.g. a certain period of time
has passed, a specific number of messages/documents have been received, the
subscriber hasn't paid.

From a CDL perspective, the "delivery address" is what the Overview Model
calls a "Channel". This means that to use it, we need to have a way of
representing the Channel in XML and decie how it should be included in the
message. My thoughts would be the body.

The rest sounds to me like a pretty regular Choreography Definition with
dependencies, e.g. you can't cancel a subscription unless you managed to
subscribe to it successfully.

Another question is should such a Pub-Sub Choreography be standardized as I
am sure the need for Pub-Sub goes beyond WS Chor. For example you could
imagine a definition that allowed you to manage a subscription to any web
service then later cancel it. However you would need standard XML docs to be
used as Message Content for the Interactions in the Pub Sub.

Also where should such a spec be developed ... by WSDL, by WS Chor? I'm not
sure I know the answer to that one. 


-----Original Message----- 
From: Steve Ross-Talbot [mailto:steve@enigmatec.net] 
Sent: Thursday, February 12, 2004 5:41 AM 
To: WS Choreography 
Subject: Fwd: WSDL and pub/sub 

How does this leave our stuff wrt the Barros usecase? 


Steve T 

Begin forwarded message: 

> From: "Jonathan Marsh" <jmarsh@microsoft.com> 
> Date: 11 February 2004 20:44:41 GMT 
> To: "Steve Ross-Talbot" <steve@enigmatec.net> 
> Subject: RE: WSDL and pub/sub 
> WSDL 2.0 part 3 [1] describes some message exchange patterns that can  
> be 
> used as part of a pub/sub solution.  Look at all the "out-*" patterns 
> starting at section 3.4.  A complete pub/sub solution is not provided, 
> as the address and mechanics of "sub"ing and providing the address for 
> the "pub" to be delivered are not standardized in WSDL (perhaps this is 
> an orchestration problem?).  Note that the HTTP and SOAP bindings don't 
> support these message exchange patterns yet, but we have an issue open 
> on whether we should rectify this. 
> Hope this helps. 
> [1] 
> http://dev.w3.org/cvsweb/~checkout~/2002/ws/desc/wsdl20/wsdl20- 
> patterns. 
> html#out-only 
>> -----Original Message----- 
>> From: Steve Ross-Talbot [mailto:steve@enigmatec.net] 
>> Sent: Tuesday, February 10, 2004 10:07 AM 
>> To: Jonathan Marsh 
>> Subject: WSDL and pub/sub 
>> Jonathan, 
>> I seem to recollect that you indiciated that WSDL2.0 includes an MEP 
> or 
>> some such facility to represent pub/sub as a means of communication. 
>> Could you verify this? And could you point me to the appropriate 
>> description? This is something that the Choreography WG would very 
> much 
>>   like to have so that a single message could be sent to multiple 
>> sources without needing to bind to those sources. 
>> Best Regards 
>> Steve Ross-Talbot 
>> co-Chair W3C Web Services Choreography 
>> O: +44 207 397 8207 
>> C: +44 7855 268 848 
>> www.enigmatec.net 
Received on Thursday, 12 February 2004 15:04:59 UTC

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