Years ago, the IETF created a working group to deal with instant
messaging and presence.  These are not terribly difficult problems,
except that security on the net at large is an unsolved problem and
that nobody has more than a very basic notion of what "presence" will
come to mean.  But, in addition to these obstacles, the IETF also
isn't always good at solving unconstrained problems, because it has no
framework for making decisions besides consensus.

Anyway, after a requirements phase that went fairly smoothly, there
was a request for submissions for protocols.  There were many
submissions, which the area directors grouped into three camps.  One
camp thought it was important to integrate instant messaging and
presence with SIP, which is a protocol for managing multimedia
sessions.  These people came up with the SIMPLE protocol.  A second
camp thought it was important to base the new standard on a new
framing layer called BEEP.  These people came up with the APEX
protocol.  A third camp thought that the first two camps were going
way into overkill territory and developed the PRIM document, which is
a direct mapping to TCP.

Because the working group was unable to get consensus on which of the
three proposals to go ahead with, they decided to let all three go
ahead and let the market decide.  In order to promote interoperability
between the protocols, a gateway standard called CPIM was developed.
This is not a protocol, although it does include a representation
format for instant messages and presence documents to faciliate
end-to-end signatures.  Rather, it is a set of semantics which each of
the protocols must comply with so that they can interoperate with the
other protocols.