Intermediaries

Here is some text that expresses my understanding of the sense of some
of the telcon conversation about intermediaries.  Please use, modify or
ignor as seems appropriate.

It is useful to draw a distinction between situations where messages are
passed through intermediaries and choreographies.  The essential issue
is that an intermediary passes along a message that is essentially, or
functionally, the same as it received.  If, on the other hand, the
purpose or function of the message is substantially changed one should
consider the situation to be a choreography.  This cannot be defined,
however, in an entirely rigorous or black and white way -- one person's
intermediary may legitimately be considered a choreography by others.
Note that since an intermediary can change the message, for example by
encrypting it or by adding ancillary information, it remains a judgment
call whether those changes are significant and functional.  In addition,
whether a service that passes messages is considered an intermediary
depends on participants in the entire chain of the message.  For
example, if sender A sends messages through I, which modifies the
messages, to receivers B and C, B might consider the modified message to
be functionally unchanged whereas C might consider it to be different
and take different action because of the modification.  In the first
case I would be considered an intermediary, in the second it would not.

Received on Friday, 5 December 2003 10:45:05 UTC