The Evolution of IM and Presence
The first widespread use of IM was ICQ and AOL’s own Instant Messenger,
which proved to be so popular that many non-AOL customers signed up for a
free IM account. The companion “Buddy List” (which allows a user to be noti-
fied when a specified set of users is active) also represents a basic presence
client. However, the first IM products used proprietary protocols and a cen-
tralized server architecture.
A large number of proprietary IM services have emerged on the Internet.
Unfortunately, as the number of incompatible IM services grows, their conve-
nience for users goes down, since users need to keep several IM applications
running all the time on their PCs. The security of proprietary IM systems is
also not known and, as a consequence, such systems must be considered a
vulnerability.
Efforts by various IM developers to interwork using IM gateways have not
been completely successful for the following reasons:
■■ Proprietary IM protocol updates make the gateway service transitory.
■■ Even technically well-working gateways between IM systems are not
enough, in our opinion, since agreements between the various IM ser-
vices are also required.
These problems and the ever larger number of IM services make the IM
gateway solution neither durable nor scalable.
As a result, there has been a strong push in the industry to develop an open
standard, interoperable, and scalable protocol for IM, similar to Internet
e-mail. This has lead to the formation of the IETF Instant Messaging and Pres-
ence Protocol Working Group (IMPP WG). This group has produced two key
documents on requirements and a model for presence and IM. It soon became
apparent, however, that:
■■ IM and presence service may be used for all other communication ser-
vices, beyond short text messaging.
■■ IM by itself can be implemented using various protocols.The commonalities and differences were clearly articulated in the IMPP WG,
and it was felt the different approaches may meet different needs and should
have a common model and data exchange format for interoperability between
the various protocols. The key document, the Common Profile for Instant Messag-
ing(CPIM) [1], was the result of this agreement in the IMPP WG.
In conclusion, the internal protocols and data formats of various IM systems
are a local business decision, but interoperability between IM systems should be
possible via CPIM. A key step in the IT market was the technical agreement by
AOL, IBM, and Microsoft on presence and IM interoperability using SIMPLE/
SIP (SIMPLE stands for SIP for IM and Presence Leveraging Extensions).
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