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Re: Re: A question about REST and transaction isolation

• To: Pete Kirkham <pete.kirkham@b...>
• Subject: Re: Re: A question about REST and transaction isolation
• From: Julian Reschke <julian.reschke@g...>
• Date: Wed, 11 Feb 2004 11:54:58 +0100
• Cc: xml-dev@l..., ari@c...
• In-reply-to: <"040211103051Z.WT03096. 15*/PN=Pete.Kirkham/OU=Technical/OU=NOTES/O=BAe MAA/PRMD=BAE/ADMD=GOLD 400/C=GB/"@MHS>
• References: <"040211103051Z.WT03096. 15*/PN=Pete.Kirkham/OU=Technical/OU=NOTES/O=BAe MAA/PRMD=BAE/ADMD=GOLD 400/C=GB/"@MHS>
• User-agent: Mozilla Thunderbird 0.5 (Windows/20040207)

Pete Kirkham wrote:
> From: 'ari@c...@INTERNET@wtgw'(K. Ari Krupnikov)
> 
>>User A GETs a resource and edits it. User B GETs a resource and edits
>>it. User A PUTs the modified resource back. User B PUTs her version of
>>the modified resource back, unaware of A's edits. A's edits are lost
>>without anyone noticing. What I want to happen is B to get a 409
>>"Conflict" or some such.
> 
> 
> This seems identical to the WebDAV use cases.
 > ...

A simple way to achieve this is just to use strong entity tags and HTTP 
If-Match headers when sending the PUT. This will avoid overlapping 
updates if all clients co-operate.

If this is not the case, WebDAV locks can be used as additional security 
measure (note that this will not help if A PUTs back after B is done).

Regards, Julian


-- 
<green/>bytes GmbH -- http://www.greenbytes.de -- tel:+492512807760

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