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Re: comments on draft-dracinschi-opes-callout-requirements-00

2002-03-01 12:33:12

On Fri, Mar 01, 2002 at 11:20:02AM -0500, Markus Hofmann wrote:
* Section 3.2.1 - 'Determining which requests are identical is
outside of the scope of a callout protocol'; how is caching
accomplished, then? Some means of indexing the cache is required.

Sure, but the mechanism to determine whether two (user) requests
are identical is a local implementation decision and has nothing to
do with the callout protocol itself. The callout protocol just
needs to provide the means to indicate cachability of a response.

If I understand correctly, then, you're saying that the protocol
provides a way to communicate hints about the cacheability (e.g.
freshness) of messages, but does not communicate the information to
actually use those hints (the cache key).

Where does it come from, then? Without either a means to specify the
key, or a common understanding between the OPES intermediary and the
OPES service of what the key is, this seems dangerous; a service
could say 'freshness is one minute' with one request profile in mind,
while the intermediary could interpret the scope of applicability in
a completely different manner.

Perhaps it would be helpful to clarify the interactions between a)
the encapsulated protocol b) the OPES service and c) the callout
protocol. Caching touches all of these in different ways, and that
might be causing the confusion here.


Mark Nottingham