On Fri, 2004/10/22 (MDT), <ho(_at_)alum(_dot_)mit(_dot_)edu> wrote:
There's a technical reason for questioning whether or not OPES
is the right thing for SMTP, and I believe Martin once gave me
a reasonable answer, but I don't think it's ever been elucidated
on this list. The question arises from SMTP being inherently
store-and-forward, as Morin points out. Thus, one would think
the the "natural" architecture for handling it would be for the
OPES processor to simply run SMTP and forward the messages to
an SMTP server where the "service enhancements" can be applied.
That SMTP server can then forward the messages onward to the appropriate
"vanilla" SMTP servers. So, why is OPES necessary?
I believe that Martin told me that it would be much easier for
developers to write OPES rules and modules for SMTP than to
write them for SMTP directly, and I suppose that makes sense if
OPES is deployed widely for HTTP and there is a base of developers
skilled in that environment. Is that an accurate statement of
the intent of the OPES/SMTP proponents? I think it would really
help if we could agree on an answer to the basic question (above).
The reason we want OPES is so that we can reuse many things common to
content adaptation, regardless of the protocol that the content came from.
We do not want to answer content integrity, men-in-the-middle, or rules
questions from scratch for every new protocol.
I may be repeating myself, but I still do not know how store-and-forward
SMTP is different from whatever-you-want-to-call-it HTTP in the context of
adapting content. Thus, for me, SMTP adaptation can be within OPES scope
if HTTP adaptation is. Using your example above, exactly the same argument
can be made for HTTP: why not forward the messages to an HTTP proxy where
the "service enhancements" can be applied...
Alex.