WGLC: p4, 304 Not Modified

Ken Murchison <murch@andrew.cmu.edu> Tue, 16 April 2013 14:13 UTC

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Date: Tue, 16 Apr 2013 10:12:06 -0400
From: Ken Murchison <murch@andrew.cmu.edu>
Organization: Carnegie Mellon University
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Subject: WGLC: p4, 304 Not Modified
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Hi All,

In re-reading the latest section 4.1, I'm wondering why ETag was singled 
out as being a MUST generate, while Last-Modified isn't.  If the server 
is capable of generating both, shouldn't it return both, as it SHOULD 
for 200 responses (per section 2.4)?  What if the client only supports 
Last-Modified and not ETag (e.g. used If-Modified-Since in its request)?

That being said, if the representation hasn't been modified then 
presumably none of the validators changed.  What's the point in 
returning any of them?  Shouldn't it be all or nothing?  Just trying to 
wrap my head around the logic behind singling out ETag over 
Last-Modified for 304.

-- 
Kenneth Murchison
Principal Systems Software Engineer
Carnegie Mellon University