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RE: Addressing Orchestration

From: Ugo Corda <UCorda@SeeBeyond.com>
Date: Tue, 25 Jun 2002 08:36:06 -0700
Message-ID: <C513FB68F8200244B570543EF3FC653708AE3514@MAIL1.stc.com>
To: "'Mark.Hapner@sun.com'" <Mark.Hapner@sun.com>, www-ws-arch@w3.org

Mark,

I surely understand that the WSA WG might not have enough resources right
now to address choreography, and I am in support of establishing a new
working group dedicated to the subject.

I imagine that this new WG will still feed information back into the WSA WG,
so that the architectural findings of the new group become integral parts of
the basic WS architecture (the same way that the WSA WG will harvest
architectural elements from XMLP and WSD).

Regards,
Ugo

-----Original Message-----
From: Mark Hapner [mailto:mark.hapner@sun.com]
Sent: Monday, June 24, 2002 10:20 PM
To: www-ws-arch@w3.org
Cc: 'www-ws-arch@w3.org'
Subject: Re: Addressing Orchestration




I agree with Ugo that the Web Services Architecture working group ideally
should
be working up a conceptual architecture that could form the framework from
which
individual work efforts relating to web services will be launched. 

However, I also agree with Dave Orchard that this is a daunting task for the
Web
Services Architecture working group, and that they already have a lot on
their
plate. Therefore, I think that the best forward is to establish a Web
Services
Choreography working group, as it has already been discussed, and use that
working group to seed the work on the next level up of the architecture. 

The currently existing Web Services Description working group is in essence
concerned with describing a set of web service operations, or stated
differently
a static web service. This is an  absolutely necessary foundation for
anything
more complex that one might want to do with web services. However, we are
now
ready to move beyond static web services, into
stateful web services that may have complex usage scenarios. 

It is this space that a choreography working group should be addressing. 

How does one define the supported usage of a stateful web service?  In
essence
this means defining a number of relationships between individual operations.


What are the allowable sequences of usage of those operations?  

What are the relationships (correlations) between the data exchanged? 

What are the transactional semantics (if any) of a sequence of operations? 

How would one compensate for a sequence of operations, since atomic
roll-back is
not relevant. 

What are the exceptions that may prevent a sequence from completing, and how
are
those
exceptions handled? 

All of these aspects of a stateful web service need to be formalized and
described in an unambiguous and coherent syntax in order for web services to
be
adopted for anything beyond the most atomic usages. 

This is the challenge of the next layer of the web service stack, on top of
WSDL, and the web services architecture working group should start meeting
this
challenge, either directly, or indirectly by recommending a new choreography
working group.

-- Mark


> Ugo Corda wrote:
> 
> Hi everyone,
> 
> Since I just joined the WSA WG, I thought of warming up for the task by
asking
> a question prompted by the recent publication of the WSCI
> spec(http://wwws.sun.com/software/xml/developers/wsci/).
> 
> It looks like Orchestration/Choreography/Workflow proposals relevant to
Web
> Services are proliferating in the industry. The ones that come to my mind
are
> IBM's WSFL, Microsoft's XLANG, BPMI's BPML, ebXML's BPSS, HP's WSCL, and
now
> WSCI.
> 
> My hope is that clarity will soon be made in this important area(s) of Web
> Services utilization. As usual, lack of clarity increases the risks of
slow
> adoption of, or resistance to, Web Services technologies in many parts of
the
> industry.
> 
> I wonder if WSA could play a role in this area, at least from the point of
> view of establishing a conceptual and architectural framework within which
the
> various proposals can be positioned, discussed, compared and selected.
(Please
> understand that I am not talking about discussing specific proposals
and/or
> establishing profiles, a role which is already being played by other
> organizations, e.g. WS-I).
> 
> I looked at the Requirements document and it does not seem to mention
> Orchestration or use any similar word. Browsing through the archives of
this
> WG, I see that the subject of Orchestration has been raised a few times in
the
> past, but my impression is that no final decision was reached regarding
> whether or how to address it. If that is the case, the recent publication
of
> yet another Orchestration spec could be the opportunity for the WG to put
a
> stake in the ground in this particular area.
> 
> Regards,
> Ugo
> 
> Dr. Ugo Corda
> Standards and Product Strategies
> SeeBeyond Technology Corporation
> 404 E. Huntington Dr., Monrovia, CA 91016
> (626) 471-6045 -- phone
> (626) 353-4851 -- cell
> (626) 471-6021 -- fax
Received on Tuesday, 25 June 2002 11:36:43 GMT

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