Subject: [core] #256: Caching text needs to be updated

From: "core issue tracker" <[email-masked]>
Date: Tue, 06 Nov 2012 01:47:00 -0000

#256: Caching text needs to be updated

 Klaus Hartke notes:

 Section 5.6

 all options match between those in the presented request and those of the
 request used to obtain the stored response (which includes the request
 URI), except that there is no need for a match of the Token, Max-Age, or
 ETag request option(s), or any request options marked as NoCacheKey
 (Section 5.4), and

 This is not entirely true, as the ETag request option may be part of the
 cache key as well:

 We have two places where we can define the properties of an option: in the
 RFC, and in the option number.

 If a proxy recognises the ETag Option, then its caching behaviour is
 defined in the RFC: the proxy determines if the ETag identifies a fresh
 response and returns either 2.03 (Valid) or not.

 If a proxy does not recognise the ETag Option, we have the choice if it's
 safe to forward it, or not.

 If it's not safe to forward, then the proxy removes it, makes the request
 towards the destination, stores the result in its cache, and returns the
 response to the client.

 But if it is safe to forward, then the server makes the request towards
 the destination *with* the ETag Option, stores the result in its cache,
 and returns the response to the client. The proxy can use the response to
 satisfy later requests only if these have the same ETag Option, because
 the origin server could have returned a different response for a different
 ETag Option value.

 So the option number must indicate to caches that do not recognise the
 ETag Option that it is part of the cache-key.

 So the text in Section 5.6 needs to be rephrased and brought in line with
 Section 5.4.2.

-- 
-----------------------------+------------------------------------
 Reporter:  zach@…           |      Owner:  draft-ietf-core-coap@…
     Type:  editorial        |     Status:  new
 Priority:  minor            |  Milestone:  post-WGLC-1
Component:  coap             |    Version:  coap-12
 Severity:  In WG Last Call  |   Keywords:
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Ticket URL: <http://trac.tools.ietf.org/wg/core/trac/ticket/256>
core <http://tools.ietf.org/core/>