ISSUE: Envelope/Body distinction

[Mark Taylor]

Should we formally distinguish the message envelope from the message body?
The same applies to responses - should they have separate envelope and 
body parts?  If so, what goes in each?

This would presumably affect the message/response encodings;
would it affect anything else?  Contributors with an opinion 
are invited to give example serializations (either XML-RPC 
or some similar representation where the structure is clear) 
for illustration.

Here is a section which appeared in an earlier draft of the document:

\subsection{Message Content}
\label{msgContent}

         Message content refers both to the semantic part of a message which
is what the sending application is trying to convey to the receiver, as well
as the structural parts of a message that may additionally include
information needed by the messaging system.  In general terms, the "body"
of a message is strictly the semantic part of the message, the "envelope"
is any part of the message providing delivery, routing, or other metadata
about the message (e.g. the timestamp it was sent).  It is dependent on the
implementation to specify the exact structure and required elements of a
message, but it is sometimes helpful to think of a message in terms of what
is being sent between applications in its entirety.  A familiar example is
an email message, where there is a clear distinction between the 'envelope'
and the 'body', but what gets delivered to the recipient is a text encoding
of both parts regardless of the intervening mail system used.

- this was removed because it did not mirror the current message/response
encoding prescriptions.  However it could be reinstated and/or a useful 
guide to how we want to do this, if we do.

-- 
Mark Taylor   Astronomical Programmer   Physics, Bristol University, UK
m.b.taylor at bris.ac.uk +44-117-928-8776 http://www.star.bris.ac.uk/~mbt/