W3C home > Mailing lists > Public > xml-dist-app@w3.org > December 2005

Re: Response envelope optional vs. response optional

From: <noah_mendelsohn@us.ibm.com>
Date: Wed, 21 Dec 2005 19:59:09 -0500
To: Mark Baker <distobj@acm.org>
Cc: Anish Karmarkar <Anish.Karmarkar@oracle.com>, xml-dist-app@w3.org
Message-ID: <OF235ED93D.4541B981-ON852570DF.0004AE3C-852570DF.00056B1E@lotus.com>

Anish:  I think you're not emphasizing as much as I am that a SOAP MEPs 
are contracts implemented by a SOAP binding to a transports nothing more.  
They are not responsible for answering every question you might have about 
which SOAP envelopes are related to which other SOAP envelopes;  the 
answer that question only insofar as a particular transport binding cares. 
  By definition, a SOAP MEP never involves more than one binding or more 
than one use of a single binding.  An MEP is a feature of a binding.

Now, let's take an example where you send over HTTP a SOAP request with a 
wsa:ReplyTo.  We use my proposed MEP and get back a 202.  In my terms, the 
MEP is done.  Note that the ReplyTo may cause a message to be sent over 
JMS, Jabber, or something completely unrelated to the HTTP binding for 
which we had an MEP.   So, that later reply will necessarily be using a 
different SOAP MEP, I.e. the one implemented by the SOAP transport used to 
for reply delivery.

My view is:

* A SOAP MEP is a contract with a particular transport binding.

* Higher level specifications, such as WSDL and/or WSA can use the SOAP 
level MEPs as building blocks to enable patterns that may be correlated 
across multiple bindings, or multiple invocations of the same binding. 
That's like saying that to order an airline ticket I'll first do a round 
trip to select a date, then another to provide my credit card.  We don't 
say that HTTP has some odd notion of double request response.  We note 
that the higher level pattern is built of repeated uses of HTTP's simple 
r/r pattern.

* SOAP MEPs allow us to document that two or more bindings implement 
similar contracts, and are thus likely to be usable in similar situations, 
sometimes even transparently to the application.  WSDL and WSA MEPs do the 
same thing for patterns that involve multiple bindings or uses of 


Noah Mendelsohn 
IBM Corporation
One Rogers Street
Cambridge, MA 02142

Mark Baker <distobj@acm.org>
Sent by: xml-dist-app-request@w3.org
12/21/2005 01:13 PM
        To:     Anish Karmarkar <Anish.Karmarkar@oracle.com>
        cc:     xml-dist-app@w3.org, (bcc: Noah Mendelsohn/Cambridge/IBM)
        Subject:        Re: Response envelope optional vs. response 


On 12/21/05, Anish Karmarkar <Anish.Karmarkar@oracle.com> wrote:
> My understanding about SOAP MEP is that: it talks about SOAP messages. A
> SOAP req-res MEP consists of one SOAP req and one SOAP res. In the case
> of 202/204, there is no SOAP response although there is HTTP response.

An HTTP response is a SOAP response.

> Hence my discomfort about the name (SOAP req-res MEP with no SOAP res).
> Alternately, specifying how the SOAP response is sent over a different
> HTTP connection is not going into higher-level messaging pattern. It
> would be merely specifying how the response part of the req-res SOAP MEP
> is sent (I'm not sure if this is the best way to go, but I don't think
> it is going into higher-level MEPs).

I'd suggest that any other "response" would be handled as part of a
separate message exchange.

Mark Baker.  Ottawa, Ontario, CANADA.       http://www.markbaker.ca
Coactus; Web-inspired integration strategies  http://www.coactus.com
Received on Thursday, 22 December 2005 00:59:20 UTC

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