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RE: Postconditions with no XML elements defined?

From: Clemm, Geoff <gclemm@rational.com>
Date: Wed, 11 Jul 2001 14:44:24 -0400
Message-ID: <3906C56A7BD1F54593344C05BD1374B1038E2069@SUS-MA1IT01>
To: ietf-dav-versioning@w3.org
We use the standard meanings of 403 and 409 defined in
RFC 2616 i.e.:

10.4.4 403 Forbidden

   The server understood the request, but is refusing to fulfill it.
   Authorization will not help and the request SHOULD NOT be repeated.

10.4.10 409 Conflict

   The request could not be completed due to a conflict with the current
   state of the resource. This code is only allowed in situations where
   it is expected that the user might be able to resolve the conflict
   and resubmit the request.

But to make sure there is no misunderstanding, how about the 
following rewording of the first paragraph of section 1.6:

A "precondition" of a method describes the state on the server that
must be true for that method to be performed.  A "postcondition" of a
method describes the state on the server that must be true after that
method has completed.  If a method precondition or postcondition for a
request is not satisfied, the response status of the request MUST be
either 403 (Forbidden) if the request should not be repeated
because it will always fail, or 409
(Conflict) if it is expected that the user might be able to resolve
the conflict and resubmit the request.

Cheers,
Geoff 

-----Original Message-----
From: Lisa Dusseault [mailto:lisa@xythos.com]
Sent: Monday, July 09, 2001 4:10 PM
To: Peter Raymond; ietf-dav-versioning@w3.org
Subject: RE: Postconditions with no XML elements defined?


I had interpreted it as being 403 with precondition, 409 with postcondition,
like you, but I agree it's not directly stated.  
 
Can the spec clarify please?
 
lisa
-----Original Message-----
From: ietf-dav-versioning-request@w3.org
[mailto:ietf-dav-versioning-request@w3.org]On Behalf Of Peter Raymond
Sent: Monday, July 09, 2001 8:39 AM
To: ietf-dav-versioning@w3.org
Subject: Postconditions with no XML elements defined?


Hi, 
In section 1.6 of the specification it states: 
In order to allow better client handling of 403 and 409 responses, a
distinct XML element 
type is associated with each method precondition and postcondition of a
request. 
But several Postconditions in the specification do not have any XML elements
defined. 
Section 8.5, 8.6, 8.7, 8.8, and 9.6 for example.  Do we need to change 1.6
to say that some 
preconditions and postconditions have distinct XML elements? 
Also regarding the 403/409 responses it was not clear from the spec when to
send 403 
and when to send 409.  The text in section 1.6 reads: 
If a method precondition for a request is not satisfied, or if a method
postcondition for a 
request cannot be achieved, the response status of the request MUST be 403
(Forbidden) 
or 409 (Conflict). 
Does this mean a 403 should be sent for a failed precondition and a 409
should be sent 
for a postcondition failure.  Or does it mean the server implementer can
return either code 
in either situation.  This is not clear from reading the spec. 
Regards, 
-- 
Peter Raymond - MERANT 
Technical Architect (ADM) 
Tel: +44 (0)1727 813362 
Fax: +44 (0)1727 869804 
mailto:Peter.Raymond@merant.com 
WWW: http://www.merant.com 
Received on Wednesday, 11 July 2001 14:37:12 GMT

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