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RE: Web Service Definition [Was "Some Thoughts ..."]

From: Cutler, Roger (RogerCutler) <RogerCutler@chevrontexaco.com>
Date: Mon, 25 Feb 2002 09:06:47 -0600
Message-ID: <3B286631A9CFD1118D0700805F6F9F5A066F8641@hou281-msx1.chevron.com>
To: "'Mark Baker'" <distobj@acm.org>, steve.vinoski@iona.com
cc: Mike.Champion@softwareag-usa.com, www-ws-arch@w3.org
I like the way that this definition is going, too, but I think that as it
stands it is too broad because I think it will include orchestrations and
the sense of the group seemed to be that orchestrations are a higher level
construction than web services.  In order to fix this I suggest that we
define a web service as having the following participants, all identified by
URI's:

1) A single "requestor".

2) A single "responder".

3) Zero or more "recipients".

A web service is initiated by a communication from the requestor to the
responder and the responder sends any number of communications to the
recipients.  All these commmunications are via web protocols.

I personally would not be unhappy about saying that the primary
communications of web services are via XML but that a web service might also
include incidental communications of other sorts -- but it seems to me that
many people want this broader than XML.

-----Original Message-----
From: Mark Baker [mailto:distobj@acm.org] 
Sent: Monday, February 25, 2002 8:16 AM
To: steve.vinoski@iona.com
Cc: Mike.Champion@softwareag-usa.com; www-ws-arch@w3.org
Subject: Re: Web Service Definition [Was "Some Thoughts ..."]


> Whoa, hold on a second, this discussion is giving me "what is an 
> object" flashbacks...OK, I think I'm better now. :-)
> 
> I think Web Services have three key elements:
> 
> 1) Identified by URI
> 2) Accessible via standard web protocols
> 3) Capable of interacting with applications and programs that are not 
> directly human-driven user interfaces, e.g. web browsers

I like this definition very much.  I'd like to rewrite it slightly, changing
two things; opening it up protocols other than "web" protocols, ensuring
that the prose suggests that individual web services be URI-identifiable,
and making sure that its recognized that it has to be all of these things,
not just one or two;

  A Web service is a service that is;

  1) identified by a URI, and
  2) accessible via standard internet protocols, and
  3) Capable of interacting with applications and programs that are not
     directly human-driven user interfaces, e.g. web browsers

I don't consider changing #2 to refer to "internet protocols" versus "web
protocols" to be a serious change, because #1 tempers the scope of the
protocol to those that operate on things with URIs.  For example, FTP is a
valid protocol to be used for a web service (despite not being commonly
recognized as a "web protocol") because it operates on files which are
things that have URIs.

> Broad? Yes. But I think it's necessary to be broad. I don't believe 
> you can define the basis of web services in terms of standards or 
> technologies, other than the web itself (which is OK given that "web" 
> already appears in its name).

+1!

MB
-- 
Mark Baker, Chief Science Officer, Planetfred, Inc.
Ottawa, Ontario, CANADA.      mbaker@planetfred.com
http://www.markbaker.ca   http://www.planetfred.com
Received on Monday, 25 February 2002 10:07:32 GMT

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