W3C home > Mailing lists > Public > www-ws-desc@w3.org > April 2003

RE: Multiple endpoints with the same interface

From: David Orchard <dorchard@bea.com>
Date: Wed, 16 Apr 2003 14:35:24 -0700
To: "'Jeffrey Schlimmer'" <jeffsch@windows.microsoft.com>, "'Kenneth Chiu'" <chiuk@cs.indiana.edu>, <www-ws-desc@w3.org>
Message-ID: <000a01c30460$175f7810$6401a8c0@beasys.com>
If I understand the CCA requirement, they would like to differentiate
between ports that are semantically equivalent versus not equivalent whithin
a single service.  This leads me to 2 questions:

1. If two ports are semantically equivalent, is there any way of talking
about the single thing that they represent?  It seems to me that there is no
way of saying what the thing is, nor expressing equivalence of the endpoints
for the singe thing.  In WS-ReliableMessaging, this "thing" is called the
ultimate receiver or the initial sender.  Each may have multiple endpoints
that are equivalent as they represent the ultimate receiver or initial

2. Is it possible to express that equivalence of porttypes also depends upon
which service they are part of?  The problem that I see is that sometimes
it's not just the porttypes that determine equivalence, it is service +
porttype.  I could have 2 equivalent port types, but when used in different
services they aren't equivalent.

I think these are separate issues, maybe I'm mistaken.  Though it does seem,
again maybe naively, that they could be satisfied with roughly one
construct.  Something like
<service name="Purchasing">
   <ultimateReceiver name="AcceptPO">
     <endpoint binding="AcceptPOSoapbinding">
	<endpoint binding="AcceptPOsomeotherbinding">
   <endpoint name="unrelatedendpoint' binding="...">

Then CCA could put endpoints that represent the same ultimate receiver in
one construct, and put endpoints that don't represent the same ultimate
receiver yet have the same interface in one service.  I'm sure there's more
that could be done about expressing the identity of the ultimate receiver
and other things, but this gives a rough outline.

I don't know if this has been talked about.  If it has, I'd appreciate any


> -----Original Message-----
> From: www-ws-desc-request@w3.org [mailto:www-ws-desc-request@w3.org]On
> Behalf Of Jeffrey Schlimmer
> Sent: Wednesday, April 16, 2003 1:18 PM
> To: Kenneth Chiu; www-ws-desc@w3.org
> Subject: RE: Multiple endpoints with the same interface
> The WG explicitly decided to keep the status quo from WSDL 1.1. As you
> note, you can work around this with multiple services.
> Alternatively, you may be interested in the solution to R085 and/or
> R131:
> R085: The description language SHOULD allow describing Messages that
> include references (URIs) to typed referents, both values and 
> Services.
> (From PP. Last discussed 11 April, 2002.)
> R131: The WG SHOULD define components that may be used within Messages
> to refer to other WSDL components. (From DO. See also R085 and R120.
> Last discussed 6 Feb 2003.)
> http://dev.w3.org/cvsweb/~checkout~/2002/ws/desc/requirements/
qs.html (ed copy)

A recent thread on this latter point begins at


> -----Original Message-----
> From: www-ws-desc-request@w3.org [mailto:www-ws-desc-request@w3.org]
> Behalf Of Kenneth Chiu
> Sent: Tuesday, April 15, 2003 10:27 PM
> To: www-ws-desc@w3.org
> We are working on a mapping from the U.S. Dept. of Energy
> Common Component Architecture (CCA) to WSDL.  CCA components
> may have multiple ports of the same type, each representing
> a different "instance".
> Because WSDL 1.1 stated that multiple ports of the same
> portType provide "semantically equivalent behavior" we have
> been mapping each CCA port to a separate service.
> What is the current thinking for 1.2?  The latest draft
> doesn't seem to have any guidance on the semantics of
> multiple endpoints of the same interface in one service.
> Kenneth Chiu
> Indiana University

Received on Wednesday, 16 April 2003 17:32:42 UTC

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