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Re: DAML-S ProcessModel

From: Massimo Paolucci <paolucci@icarus.cimds.ri.cmu.edu>
Date: Fri, 16 May 2003 12:53:26 -0400
Message-ID: <16069.6022.105688.113700@icarus.cimds.ri.cmu.edu>
To: www-ws@w3.org


There are many reasons why a Web services may want to display its
process model.  The first one is that its clients can derive the
interaction protocol from the Process Model.  For example a book
selling Web service like Amazon allows you to browse and to reserve
the book (amazon's web service does not allow to buy right now).  so
you could have a process model that looks like
sequence(browse-atomic-process, reserve-atomic-process).  The client
at this point knows that first it has to deal with the browsing
task, then with the reserve task.  Acting differently from what the
process model require will lead to errors.   

But there are other reasons.  I understand that supply chain
management depends on the providers to provide information on the
state of processing of the different orders.  Ultimately this requires
the providers to display parts of their process model.  Also, during
composition of web services clients need to know details on how the
web service performs its tasks so they can integrate different
serices.  For example, before spending some money a client may want to
make sure that there is money in an account.  This requires careful
composition of the process model of the selling Web service (which
withdraw the money from the account) with the process model of the Web
service of the Bank that holds the account (which tells if there is
enough money).

Ultimately, the DAML-S Process Model allows implementors of Web
services to display as much of the Web service they want to display.
If they do not want to display anything, they use only one atomic
process.  Minimally, they have to display enough information to allow
their clients to derive the interaction protocol, and in a way this is
what e-shops do already (amazon or orbitz ask you quite a few
questions before letting you to buy something) everything else it is
up to their business model and what they want to achieve.

I hope that this helped,

--- Massimo

Sudhir Agarwal writes:
 > Dear all,
 > i currently can not understand the purpose of the ProcessModel completely. I 
 > understand why an AtomicProcess is needed. But, why does ComplexProcess 
 > exist? Isn't it enough to have only AtomicProcess? Why should a web service 
 > provider show how his services works? On the other hand, im not sure that a 
 > web service requester is interested in knowing all that (if-then-else, while, 
 > split, fork etc.) stuff as long as the service does what he wants. Even if 
 > someone really wants to know that, what can he do with that knowledge? Does 
 > it help him in any way?
 > could someone help me?
 > Thanks and regards
 > Sudhir
Received on Friday, 16 May 2003 12:53:56 UTC

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