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Editorial issue - Terminology for Operation types

From: David Booth <dbooth@w3.org>
Date: Mon, 20 May 2002 12:52:42 -0400
Message-Id: <>
To: www-ws-desc@w3.org
This is an editorial issue regarding the terms that we use for the four 
kinds of operations or message exchange patterns described in WSDL: 
"One-way", "Request-response", "Solicit-response" and "Notification".

These four terms are not very consistently selected, nor are they clearly 
descriptive of their purpose. For example:

1. The word "response" is overloaded.  From the perspective of a Web 
Service that is interacting with a Client, we have the following terms defined:

"Request-response" represents an input-output pair of messages
"Solicit-response" represents an output-input pair of messages

These terms use different words for the initiating message, depending on 
whether the respondent is the Client or the Web Service: "Request" if the 
initiator is the Client; "Solicit" if the initiator is the Web 
Service.  However, they use the same word ("response") for the returned 
message, even though the  respondent differs.  It would be editorially 
clearer to be consistent.

2. As an operation type, the term "One-way" is not very clear.  It does 
describe a message exchange pattern involving only one message that is sent 
in one direction (from Client to Web Service).  But the "Notification" 
operation also describes a message exchange pattern involving only one 
message that is sent in one direction -- in this case from Web Service to 
Client.  Again it would be editorially better to use terms that are more 
consistent and/or more distinctly descriptive.


As a solution to these problems, I would suggest using the terms "Input", 
"Input-Output", "Output-Input", and "Output" instead of the terms 
"One-way", "Request-response", "Solicit-response" and "Notification".  In 
other words, define the following four terms for the four kinds of operations:

Input (a/k/a "One-way"). The endpoint receives a message.
Input-Output (a/k/a "Request-response"). The endpoint receives a message, 
and sends a related message.
Output-Input (a/k/a "Solicit-response"). The endpoint sends a message, and 
receives a related message.
Output (a/k/a "Notification"). The endpoint sends a message.

I think this change would help make the specification simpler, clearer and 
more consistent.

David Booth
W3C Fellow / Hewlett-Packard
Telephone: +1.617.253.1273
Received on Monday, 20 May 2002 22:33:15 UTC

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