> From: Markus Buchhorn <markus@acsys.anu.edu.au>
> Subject: Re: Taxonomy Term closure needed
>
> At 17:40 9/09/99 -0700, Joe Touch wrote:
> >A cache is a system which stores temporary copies of response messages,
> >and replays them when prompted.
>
> .. of successful response messages..? or somesuch - not much point caching
> error results.
Sure there is. If the error is from the server, not a meta-error
about not being able to reach it. I.e., if the content isn't there,
why keep going back?
> And there's also the question of permission/time - being
> allowed to cache a response (Pragma: No-Cache; Expires: Now).
That is a complication that isn't useful in the definition.
There's nothing about a cache that says that the cached result
is useful - it's just replayed.
> >> Reverse Proxy
> >
> >This is the one I find odd. There is nothing reverse about it.
> >It's just a proxy cache co-located (or nearly-colocated) with the server.
> >
> >Why not just call it a "server-side, or server-proximal" cache?
>
> Agreed. A 'server-side' cache is designed to take load off the origin
> server, but does nothing for the network or performance as seen by the
> end-user.
I can affect the performance seen by the end user, if
that performance is limited by the server bottleneck.
If that server-side cache pushes, uses multicast, etc,
it can also reduce network load.
> A 'network' cache is designed to speed up responses for the
> end-user and reduce network load.
s/and/or - it can be either.
> The term 'Reverse Proxy' to me sounds like a pre-populated caching proxy...
>
> >> Second Derivative Terms: (Build upon first derivative terms)
> >> Caching Proxy
> >> A new defintion. Editors View - Consensus
> >> "A proxy with a cache, acting as server to clients, and
> >> a client to servers"
> >
> >And which intercepts requests that have associated responses
> >in its cache.
>
> No - it "intercepts" _all_ requests, but if it can't service them will
> forward them on on behalf of the client, and store the response while also
> passing it on.
Define "intercept" - I was intending it to mean what you do with
messages you don't forward. You mean something different. Maybe
'responds to' is better than 'intercepts'?
> And depending on the application it may not be an
> "intercept" (which sounds like a hijack) it may be a deliberate direct
> request ("have you got this? If not please get it for me").
In that role the caching proxy is acting like a server (something
that is explicitly addressed). While anything we can create
can have any combination of these capabilities, the definitions
focus on the 'pure' forms of each capability, no?
> >> Replica Origin Server
> >> New definition. Editors View - Open Disussion
> >> Editors-Note: In light of the recent disuccsion, the authoritative
> >> attribute is quiestionable.
> >> "origin server storing a persistent replica of a data set
> >> stored at the authoritative reference"
>
> How is this different to a mirror ?
I think a mirror is about the entire server; a replica is about an object.
I.e., 'servers (or databases, or data sets) are mirrored;
'individual objects are replicated'.??
Joe
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