RFC 2778 (rfc2778) - Page 2 of 17

A Model for Presence and Instant Messaging

RFC 2778       A Model for Presence and Instant Messaging  February 2000


   In this document, each element of the model appears in upper case
   (e.g., PRESENCE SERVICE). No term in lower case or mixed case is
   intended to be a term of the model.

   The first part of this document is intended as an overview of the
   model.  The overview includes diagrams, and terms are presented in an
   order that is intended to help the reader understand the relationship
   between elements. The second part of the document is the actual
   definition of the model, with terms presented in alphabetical order
   for ease of reference.

   The overview is intended to be helpful but is not definitive; it may
   contain inadvertent differences from the definitions in the model.
   For any such difference, the definition(s) in the model are taken to
   be correct, rather than the explanation(s) in the overview.

2. Overview

   The model is intended to provide a means for understanding,
   comparing, and describing systems that support the services typically
   referred to as presence and instant messaging. It consists of a
   number of named entities that appear, in some form, in existing
   systems. No actual implementation is likely to have every entity of
   the model as a distinct part. Instead, there will almost always be
   parts of the implementation that embody two or more entities of the
   model. However, different implementations may combine entities in
   different ways.

   The model defines two services: a PRESENCE SERVICE and an INSTANT
   MESSAGE SERVICE. The PRESENCE SERVICE serves to accept information,
   store it, and distribute it.  The information stored is
   (unsurprisingly) PRESENCE INFORMATION. The INSTANT MESSAGE SERVICE
   serves to accept and deliver INSTANT MESSAGES to INSTANT INBOXES.

2.1 PRESENCE SERVICE

   The PRESENCE SERVICE has two distinct sets of "clients" (remember,
   these may be combined in an implementation, but treated separately in
   the model).  One set of clients, called PRESENTITIES, provides
   PRESENCE INFORMATION to be stored and distributed.  The other set of
   clients, called WATCHERS, receives PRESENCE INFORMATION from the
   service.









Day, et al.                  Informational