First, this is a public mailing list, see the ietf.org website about
policies governing working group mailing lists. Don't post anything
here that you want "protected" or "respected" by competitors.
OPES works with HTTP messages. We may address RTP in the future.
Your "overlay" looks very much like an ordinary operating system's
API to network protocols, so I'm unsure what its point is. Your comment
about "not necessarily under IP" is confusing because it's more common
to speak of these protocols as running "over" IP (or do you you mean
"intellectual property"? :-) ). Trying to continue guessing, I'll ask
if you mean that the "dispatcher" is remotely controlled, using something
like OPES rules? Are you suggesting that this function be implemented
as a "web service"?
A few years ago I saw a system called "Delegate" that provided a
fairly general API so that people could write filters that could take
in data from one (protocol, port) pair and forward that data (possibly
altered) to another pair or deliver it locally. It might be closer to
what you are describing than OPES is. OPES is more specific, and it
concentrates on some details of HTTP (and possibly RTP) semantics, the
callout protocol, and issues about configuration and tracing.
It might help the discussion if you could give some examples of what
you'd like to see systems like this do.
Hilarie