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RE: Some proposed definitions of "web service" based on the call toda y

From: Newcomer, Eric <Eric.Newcomer@iona.com>
Date: Sat, 19 Apr 2003 15:12:45 -0400
Message-ID: <DCF6EF589A22A14F93DFB949FD8C4AB20107436B@amereast-ems1.IONAGLOBAL.COM>
To: "Christopher B Ferris" <chrisfer@us.ibm.com>, <www-ws-arch@w3.org>
I still have the problem with defining the agent as the service.  The service is mapped or transformed onto the agent.  Saying that a Web service is an interface to an agent, a representation of an agent, or a description of an agent are all ok with me, but I can't (for example) see anything in SOAP, WSDL, etc. that defines what the agent is or has to be.

-----Original Message-----
From: Christopher B Ferris [mailto:chrisfer@us.ibm.com]
Sent: Friday, April 18, 2003 8:00 AM
To: www-ws-arch@w3.org
Subject: Re: Some proposed definitions of "web service" based on the call toda y



I would prefer that we not include references to version numbers in the definition, as these will 
change over time. I think that the acronyms should suffice. Secondly, I thinn that qualifying SOAP by 
calling out the XML Infoset and processing model suggests that other aspects of SOAP are either 
not used, or not allowed, or who knows what. I think that it is sufficient to say just SOAP. Finally, since 
we have spent some time discussing the various types of ways in which people have been using the term, 
I felt that it is probably worthwhile that we share some of these alternate uses with the readers of the 
WSA and give them a little more background. 

How 'bout this: 
------------------------------------------------------------------------- 
The term "Web service" has been used to refer to a wide variety of things, 
and it is clear that not all people share the same understanding and definition. 
For some, it has meant simply the exchange of XML over the Web, typically using HTTP. 
For others, it has meant simply the exchange of SOAP messages, typically using HTTP, 
or some software component that has been described using WSDL. In a sense, all of these 
things might be considered to be "Web services", and the Working Group does not 
preclude the use of the term to describe these sorts of things. Nevertheless, for 
the purposes of this document, we will define the term Web services as follows: 

[Definition: Web service - an executable software agent that is identified by 
a URI and whose interface and binding(s) are described using WSDL. Other software agents 
interact with a Web service in a manner prescribed by its WSDL description, using SOAP.] 

--------------------------------------------------------------------------------------------------------------------------------------------------- 

Now, this definition probably deserves some further explanation in order to say things like  "there's nothing 
to preclude the use of other protocols (than SOAP) to interact with a Web service... for the purposes of this document, we simply 
aren't going to go there" and "while the definition requires the use of WSDL, it does not preclude the use of 
other technologies or XML vocabularies for its description. however, for the purposes of this document, we 
aren't going to go there..." 

Again, it might be nice to solve the equation for all possible solutions to WS = U + Xd + Xm (a web service is identified 
by a URI and described using XML and interacted with using XML messages) IMO this represents a daunting 
task. We should be focused on defining an architecture that leverages the technologies being developed 
in our sibling WGs in the Web Services Activity in its realization. 

Cheers, 

Christopher Ferris
Architect, Emerging e-business Industry Architecture
email: chrisfer@us.ibm.com
phone: +1 508 234 3624 

www-ws-arch-request@w3.org wrote on 04/17/2003 05:36:27 PM:

> 
> Whew, that was fun :-(  Although it got better when we stumbled on the
> "instant straw poll in IRC" idea; we should do that more often.  I'd say
> that in general, anyone who has the "floor" in the speaker queue may propose
> one of those by typing the question into IRC; those not on IRC can ask to
> have their vote recorded by someone who is.
> 
> Let me throw out some proposals that reflect the various opinions I heard
> today; without my co-chair hat on, I could live with either of them:
> 
> ===========================================================================
> The term "web service" is used in a wide variety of ways by different
> people, and we will not presume that the definition used here is consistent
> with all of them.  Nevertheless, for the purposes of this document, we will
> use the term to mean the following: A Web service is [an interface to ?] an
> executable software agent that is designed to be used by another software
> agent.  A Web service is
> identified by a URI, and MUST be [capable of being ?] formally defined in
> WSDL 1.2.  A software agent interacts with an  Web service in the manner
> prescribed by the formal definition, using the XML Infoset and processing
> model defined by SOAP 1.2.
> 
> [Chris said some things about SOAP being general enough to describe any
> reasonable "web service" interaction that I didn't capture very well ...
> maybe he can refresh my memory.]
> 
> ==========================================================================
> 
> The term "web service" is used in a wide variety of ways by different
> people, but there is a rough consensus along the following lines: A Web
> service is an interface to an executable software agent that is designed to
> be used by another software agent.  A Web service is identified by a URI,
> and has a definition in a language sufficient to describe the interface to
> developers of client agents. A software agent interacts with a Web service
> in the manner that is consistent with the description, using standard
> protocols. 
> 
> That definition of "web service" is not sufficiently precise or rigorous for
> architectural purposes, however.  We will use a more restrictive term to
> describe the scope of the architecture described here: "Extensible XML Web
> Services", abbreviated XWS.   the purposes of this document, we will use the
> term to mean the following: An XWS is an interface to an executable software
> agent that is designed to be used by another software agent.  An XWS is
> identified by a URI, and MUST be capable of being formally defined in WSDL
> 1.2.  A software agent interacts with an  Web service in the manner
> prescribed by the formal definition, using the XML Infoset and processing
> model defined by SOAP 1.2."
> 
> ["XWS" is essentially a placeholder for some term ... I don't care what it
> is, but it must specifically describe the "MUST" constraints specified by
> the WSA.]
> 
> ==========================================================================
> Of course, improved definitions are solicited.
> 
Received on Saturday, 19 April 2003 15:19:04 GMT

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