Re: WGLC: p5 MUSTs

Ken Murchison <murch@andrew.cmu.edu> Wed, 01 May 2013 13:36 UTC

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Date: Wed, 01 May 2013 09:33:37 -0400
From: Ken Murchison <murch@andrew.cmu.edu>
Organization: Carnegie Mellon University
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Subject: Re: WGLC: p5 MUSTs
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On Tue, 30 Apr 2013 19:18:49 -0600,
Alex Rousskov wrote:
> > Clients MUST NOT use an entity-tag marked as weak in an If-Range
> > field value and MUST NOT use a Last-Modified date ...
>
> Please replace "use" with "generate" to explicitly exclude proxies from
> policing these headers (i.e., to allow proxies to forward these headers
> "as is"). This was already done for other If-Range header rules, but
> these two MUST NOTs have slipped through the cracks.
>   
Clients don't generate ETags, they just use what they have seen in 
responses from servers.  I think the sentence would have to be reworded 
to something like:

"Clients MUST NOT generate an If-Range field value containing an 
entity-tag marked as weak and MUST NOT generate an If-Range field value 
containing a Last-Modified date..."

> > 4.1 206 Partial Content
>
> Since HTTPbis no longer allows multipart/byteranges media type to
> determine the message body length, perhaps it would be a good idea to
> explicitly mention that a server MAY generate a 206 Partial Content
> response (with single or multiple ranges) without a Content-Length
> header and may use chunked encoding? I bet many clients will break when
> this starts happening, and there are currently no examples or warnings
> that would prepare developers for that possibility.
>   
A HTTP/1.1 server can always use chunked encoding for a response and any 
HTTP/1.1 client that can't handle chunked or doesn't expect it for a 
certain response code is already broken.  I don't see the need to 
specifically call this out for a 206 response.

-- 
Kenneth Murchison
Principal Systems Software Engineer
Carnegie Mellon University