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Re: SOAP and the Web architecture

From: Paul Prescod <paulp@ActiveState.com>
Date: Mon, 27 Aug 2001 18:41:55 -0700
Message-ID: <3B8AF6E3.9AA4EF1D@ActiveState.com>
CC: "'xml-dist-app@w3.org'" <xml-dist-app@w3.org>
"Jones, Matthew" wrote:
> 
>...
> 
> POST does not have side effects anymore than GET does.  You can send exactly
> the same form via POST or GET and it will do exactly the same thing.  The
> fact that POST has more general capability might make it more likely that
> POST requests have side effects but there is nothing inherent in the POST
> that makes this so.  Furthermore GET is not necessarily idempotent, you can
> certainly write a service so it will be idempotent or not but GET does not
> guarantee idempotency.

True. Protocols cannot guarantee anything at all. But they are means of
communication between conforming systems.

"9.1.1 Safe Methods
Implementors should be aware that the software represents the user in
their interactions over the Internet, and should be careful to allow the
user to be aware of any actions they might take which may have an
unexpected significance to themselves or others. 

In particular, the convention has been established that the GET and HEAD
methods SHOULD NOT have the significance of taking an action other than
retrieval. These methods ought to be considered "safe". This allows user
agents to represent other methods, such as POST, PUT and DELETE, in a
special way, so that the user is made aware of the fact that a possibly
unsafe action is being requested. 

Naturally, it is not possible to ensure that the server does not
generate side-effects as a result of performing a GET request; in fact,
some dynamic resources consider that a feature. The important
distinction here is that the user did not request the side-effects, so
therefore cannot be held accountable for them."

-- 
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Received on Monday, 27 August 2001 21:42:27 GMT

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