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RE: How to determine if an operation is synchronous

From: Ugo Corda <UCorda@SeeBeyond.com>
Date: Wed, 23 Oct 2002 08:19:55 -0700
Message-ID: <C513FB68F8200244B570543EF3FC65370A855BDE@MAIL1.stc.com>
To: "'Assaf Arkin'" <arkin@intalio.com>
Cc: www-ws-arch@w3.org

You are still implying that a request/response operation must be synchronous
(even though it might be implemented by two asynchronous communications). I
am saying that the request/response operation itself can be asynchronous.
Let's just agree to disagree.


-----Original Message-----
From: Assaf Arkin [mailto:arkin@intalio.com]
Sent: Tuesday, October 22, 2002 10:08 PM
To: Ugo Corda
Cc: www-ws-arch@w3.org
Subject: RE: How to determine if an operation is synchronous

A synchronous operation can be performed by two asynchronous communications.
WSDL 1.1 allows you to specify a protocol binding that will use two
separate, opposite direction, one message exchanged, asynchronous
communications. The protocol would be asynchronous. The operation would be
synchronous. The two do not stand in conflict.

If you go back to my previous e-mail explaining the relation between node A
and node B, and how they 'synchronize' by performing such an operation, you
will see that nothing there says the message exchange is synchronous. In
fact, if you use a synchronous protocol like HTTP you probably don't need
all the lengthy time computation. You need that if you use an asynchronous
protocol with a significant latency as proof that the operation is


-----Original Message-----
From: Ugo Corda [mailto:UCorda@SeeBeyond.com]
Sent: Tuesday, October 22, 2002 9:51 PM
To: 'Assaf Arkin'
Cc: www-ws-arch@w3.org
Subject: RE: How to determine if an operation is synchronous

>From a WSDL operation definition you can determine that it is:
>- asynchronous  The operation involves a single message (one-way and
>notification in WSDL 1.1)
>- synchronous  The operation involves two messages in opposite directions,
>and indicates that it completes after receiving one and sending the other
>(request-response and solicit-response in WSDL 1.1)

Sorry, I disagree. I believe that a request-response operation can be either
synchronous or asynchronous. The author of the IBM series of articles on
asynchronous Web services messages seems to have the same belief. Look at
[1] (part 2 of the series), Pattern 2, Request/reply operations, where he
says: "In this pattern, request and response are two messages defined within
a single request/reply operation and sent as two separate and unrelated
transport-level transmissions."


[1] http://www-106.ibm.com/developerworks/library/ws-asynch2/index.html
Received on Wednesday, 23 October 2002 11:20:27 UTC

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