[e2e] e2e principle..where??....

Eric A. Hall ehall at ehsco.com
Fri Jun 1 22:03:48 PDT 2001

"Roy T. Fielding" wrote:

> HTTP places application semantics within every message in order to
> make them visible to intermediaries, thus preserving end-to-end
> principles when the protocol is used faithfully.

But are the intermediaries being faithful? or are they changing headers
and doing other things to the data?

The true end-points are the nodes that exchange data directly, not the
ultimate source or destination for the data.

We can say that there are tremendous benefits to caches to have them
intercept HTTP data, but that is a convenience, not a requirement of the
client-cache connection. The cached data could just as easiily have been
populated by a filesystem or a database query as it was from HTTP. The
ultimate end-to-end link will be between the client and the cache, not the
client and the server, and so the protocol semantics and other aspects of
the cache-server link are irrelevant.

Eric A. Hall                                        http://www.ehsco.com/
Internet Core Protocols          http://www.oreilly.com/catalog/coreprot/

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