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Re: 304 or 412 for If-Modified-Since?

From: Julian Reschke <julian.reschke@gmx.de>
Date: Wed, 30 Jun 2010 07:11:07 +0200
Message-ID: <4C2AD1EB.4010705@gmx.de>
To: Cyrus Daboo <cyrus@daboo.name>
CC: WebDAV <w3c-dist-auth@w3.org>
On 30.06.2010 03:29, Cyrus Daboo wrote:
> Hi folks,
> RFC 2616 in Section 14.25 "If-Modified-Since" states that a 304 should
> be returned if the resource is not modified.


> RFC 4918 in Section 12.1 "412 Precondition Failed" states that a 412
> should be returned when a conditional header fails to hold.

That should be reported as an RFC 4918 erratum. WebDAV can't override 
normative requirements from HTTP/1.1. (

> So what should clients expect from WebDAV servers?

They should expect that headers defined in RFC 2616 work as advertised 

> Second, does If-Modified-Since make sense for PROPFIND or REPORT requests?

If the resource being addressed responds to GET, and does to with a 
Last-Modified header, then it makes sense for consistency. However, GET 
in a collection *usually* only returns information based on the state of 
the collection and its direct members, so it wouldn't be useful for 
PROPFIND/Depth=Infinity, and might not be useful at all for REPORT.

Of course the same question could be asked about If-None-Match.

I think making PROPFIND/REPORT responses more Web-friendly (adding a way 
to GET those) would help with this issue (hint, hint).

Best regards, Julian
Received on Wednesday, 30 June 2010 05:11:48 UTC

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