Re: NEW ISSUE: Content-* headers vs PUT

Roy T. Fielding wrote:
> 
> On Jul 25, 2007, at 10:35 AM, Julian Reschke wrote:
>> the description of PUT states 
>> (<http://greenbytes.de/tech/webdav/rfc2616.html#rfc.section.9.6.p.1>):
>>
>> "The recipient of the entity MUST NOT ignore any Content-* (e.g. 
>> Content-Range) headers that it does not understand or implement and 
>> MUST return a 501 (Not Implemented) response in such cases."
>>
>> It's not clear to me what Content-* headers are? All headers starting 
>> with the character sequence "Content-"? Just those defined in RFC2616?
> 
> Any header field name that begins with Content- (as reserved by MIME).
> 
>> Furthermore, that language sounds as if a server that ignores 
>> Content-Language (as opposed to storing it with the entity) MUST 
>> reject PUT requests that come with a Content-Language header. Is this 
>> really intended? Does anybody implement that?
> 
> No.  The only reason it is in the spec, IIRC, is because some folks
> wanted to squeeze Content-Range on PUT into the spec in spite of the
> fact that it was known to fail interoperability on all deployed
> servers.  Thus, an incompatible requirement was added to HTTP, over
> the objections of the real vendors, in order to promote a feature that
> did not yet exist.  It didn't work then, still doesn't work, and should
> be removed from the spec.

So I understand your recommendation would be to completely drop the 
requirement, dropping the last sentence from Section 9.6, p1 
(<http://greenbytes.de/tech/webdav/rfc2616.html#rfc.section.9.6.p.1>):

"The recipient of the entity MUST NOT ignore any Content-* (e.g. 
Content-Range) headers that it does not understand or implement and MUST 
return a 501 (Not Implemented) response in such cases."

?

> PATCH is a better solution.  In PATCH, all of the Content- headers
> refer to the patch entity. Any metadata that needs to be changed as
> part of the PATCH can be changed through the use of a patch format
> that contains metadata-deltas.

Agreed.

That also means that the same sentence should be removed from the PATCH 
spec, then.

Best regards, Julian

Received on Thursday, 26 July 2007 10:38:53 UTC