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What it means to "get rid of MEPs"

From: <noah_mendelsohn@us.ibm.com>
Date: Wed, 21 Dec 2005 13:46:15 -0500
To: xml-dist-app@w3.org
Message-ID: <OF3D3A9523.183A9131-ON852570DE.0066D2C3-852570DE.00672AF5@lotus.com>
At the end of today's call we had an interesting discussion about what 
MEPs are, to what degree state machines are part of them, etc.  SOAP 1.2 
is very clear on what MEP's are [1]:

3.2 SOAP Message Exchange Patterns (MEPs)
A Message Exchange Pattern (MEP) is a template that establishes a pattern 
for the exchange of messages between SOAP nodes. MEPs are a type of 
feature, and unless otherwise stated, references in this specification to 
the term "feature" apply also to MEPs. The request-response MEP specified 
in SOAP 1.2 Part 2 [SOAP Part 2] illustrates the specification of a MEP 
The specification of a message exchange pattern MUST:
As mandated by 3.1.1 Requirements on Features, provide a URI to name the 
Describe the life cycle of a message exchange conforming to the pattern.
Describe the temporal/causal relationships, if any, of multiple messages 
exchanged in conformance with the pattern (e.g. responses follow requests 
and are sent to the originator of the request.)
Describe the normal and abnormal termination of a message exchange 
conforming to the pattern.
Underlying protocol binding specifications can declare their support for 
one or more named MEPs.
MEPs are SOAP features, so an MEP specification MUST conform to the 
requirements for SOAP feature specifications (see 3.1.1 Requirements on 
Features). An MEP specification MUST also include:
1.      Any requirements to generate additional messages (such as 
responses to requests in a request/response MEP).
2.      Rules for the delivery or other disposition of SOAP faults 
generated during the operation of the MEP.

If we get "rid" of MEPs as a concept, then we delete this text from SOAP 
part 1.  I'm currently against doing that, but that's what it would 

There are obviously concerns about state machines etc.  It should be clear 
from the above that the particular style of state machines in part 2 are 
not fundamental to being an MEP;  they are an editorial device that was 
adopted set down in detail the particular MEPs provided.  Maybe or maybe 
not we should either change them or re-express them in simpler form, but 
doing so is not IMO best described as getting rid of MEPs.


[1] http://www.w3.org/TR/soap12-part1/#soapmep

Noah Mendelsohn 
IBM Corporation
One Rogers Street
Cambridge, MA 02142
Received on Wednesday, 21 December 2005 18:47:36 UTC

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