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Some comments on the PATCH draft

From: Andreas Sewe <sewe@rbg.informatik.tu-darmstadt.de>
Date: Tue, 03 Jul 2007 14:32:29 +0200
Message-ID: <468A41DD.9060400@rbg.informatik.tu-darmstadt.de>
To: ietf-http-wg@w3.org

James Snell, the author of the recently revived PATH draft, has asked me
to resend my comments for further discussion to this list. (Originially
I send my comments to James only.)

So here they are:
> What bothers me currently about the PATCH draft is that it refers
> to resources throughout even though what is actually patched is a
> *representation* of a resource.
> 
> Besides being an issue of terminology this also has some
> implications when content negotiation is used. Granted, content
> negotiation complicates things quite a bit and might not be
> needed in most cases, but since PUT works fine even for
> negotiated resources I have the feeling that PATCH should work,
> too.
> 
> The problem with the draft is, however, that the content type of
> the entity send cannot be determined, since the Content-Type
> header contains (rightly so!) application/diff or some such type.
> But the assumption that the base media type is that of the
> resource is false as soon as that resource has many different
> representations. Which representation should the diff be applied
> to?
> 
> Representations might differ by Content-Type, Content-Language,
> etc., information which can be found in the Vary header. But
> besides Content-Type the other headers can be provided directly;
> only Content-Type carries the diff format's media type.
> 
> Unfortunately, I can't think of a clean solution of the top of my
> head; both adding a header like Patched-Type and requiring a
> media type parameter like application/diff;type="text/plain" seem
> clumsy to me. But if PUT works with content negotiation, so
> should PATCH!
> 
> Regards,
> 
> Andreas
Received on Tuesday, 3 July 2007 12:32:35 GMT

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