Alex,
yes I agree with your assement.
This case is beyond OCP.(although in theory u can still use OCP but the question is why?)
Should we call it distributed OPES processor (where performance does not count)
abbie
> -----Original Message-----
> From: Alex Rousskov [mailto:rousskov@xxxxxxxxxxxxxxxxxxxxxxx]
> Sent: Friday, April 11, 2003 12:03 AM
> To: ietf-openproxy@xxxxxxx
> Subject: Re: Shortcuts
>
>
>
> On Thu, 10 Apr 2003, The Purple Streak, Hilarie Orman wrote:
>
> > I had a returned thought on the issue of whether or not data had to
> > complete the loop between the OPES processor and the
> callout server.
> > If the proxied protocol is a store-and-forward type, like
> SMTP, then
> > it seems that the callout server might, quite properly, send
> > transformed messages directly to an application endpoint
> (SMTP server)
> > without going back through the OPES processor.
> >
> > If this is proper, should we document it. If it is
> improper, can we
> > say why?
>
> Excellent question!
>
> If a callout server accepts application message and then just
> forwards an adapted version elsewhere, it is not (should not
> be) a callout server. It is an OPES processor! Thus, it is
> absolutely proper to do that as long as the entity in
> question does not pretend to be a callout server and obeys
> all processor requirements.
>
> Here is what you get in that case:
>
> -- (SMTP) --> OPES --> (SMTP) --> OPES --> (SMTP)
> processor 1 processor 2
>
> Which is perfectly fine and is obviously beyond OCP scope
> (OCP is not involved here).
>
> If, for some unnatural reason, the same thing is implemented
> using OCP, it may still be OPES-legal as long as both OPES
> agents know what they are doing:
>
> callout server
> -- (SMTP) --> OPES --> (OCP) --> _and_ OPES --> (SMTP)
> processor 1 processor 2
>
> Essentially, "adaptation service" here means "I took care of
> it, forget it". This is OK as long as processors cooperate.
> Note that the callout server would be required to respond
> with that "I took care of it" application message to its OPES
> processor 1 (that application message/response will probably
> have no payload though, just metadata). No need to documented
> this convoluted case, IMO.
>
> A somewhat similar but more realistic example with an "I took
> care of it" response would be a "black hole" service (e.g., a
> SPAM filter):
>
> -- (SMTP) --> OPES --> (OCP) --> callout
> processor 1 server
>
> The latter might be worth documenting in an "SMTP adaptation
> using OPES" draft.
>
> HTH,
>
> Alex.
>
>
>