Re: Caching Question re Paging

* Robert Sanderson <azaroth42@gmail.com> [2015-04-08 15:23-0700]
> All,
> 
> A hopefully quick and already discussed question about paging and its
> interaction with web caches.
> 
> The recommendation in 6.2.6 is to allow the server to either issue a 200
> with the full representation as the body, OR when it receives a Prefer
> header that requests paging, to instead return a 303 redirecting to the
> first page.
> 
> This seems like it will make web caches constantly invalidate the responses
> as paging and non-paging clients make requests, thereby reducing the
> ability for the infrastructure to cope exactly where it's most needed --
> the large 200 responses.  This could be signaled to the web caches by
> including a Vary header with the value of Prefer, but I don't see that
> anywhere in the document.
> 
> According to 2616, 303 isn't cacheable without explicit cache control
> headers but 200 is.  So with the Vary header, the small 303s should pass
> through without disturbing the cached 200. In theory. I think :)
> 
> Am I missing something obvious that makes all of this null and void and
> it's already been discussed and discarded as unnecessary?

Only tangentially. The 2nd to last paragraph of RFC 7240 "Prefer
Header for HTTP" says that
[[
                             If a server supports the optional
   application of a preference that might result in a variance to a
   cache's handling of a response entity, a Vary header field MUST be
   included in the response listing the Prefer header field regardless
   of whether the client actually used Prefer in the request.
]]
so technically we're all set. That said, it might be nice to mention
that to the reader. Can you propose and editorial change?


http://tools.ietf.org/html/rfc7240#section-2
or just above
http://tools.ietf.org/html/rfc7240#section-2.1


> Thanks!
> 
> Rob
> 
> -- 
> Rob Sanderson
> Information Standards Advocate
> Digital Library Systems and Services
> Stanford, CA 94305

-- 
-ericP

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Received on Monday, 13 April 2015 14:40:40 UTC