> I think we also need some kind of message subtype in MIME that does things
> similar to message/external-body but resolves URIs and/or URNs. I don't see
> this as being something that can be just another access-type under
> message/external-body because of the semantics peculiar to the HTTP way of
> resolving URIs (specifically, that the content-type is selected by the
> server in response to what the client indicates it can handle).
There is a need for a URN-like thing that can be absoultely tied to a
particular format of an object. Without such a URN there is no way to
cache/replicate objects correctly.
This doesn't preclude HTTP (or gopher, or whatever) from doing "conversion"
from a primary format to another format on behalf of the client.
A properly designed URN/URL system would not prevent use of MIME's
message/external-body with URNs, though it might not allow conversion
on-the-fly in this case.
Keith