Chapter 16. Presence and Instant Messaging
In this chapter, we will present a very popular IP-based communications service called instant messaging and the presence service traditionally associated with it. Again we will see that SIP can play an important role in order to deliver these services.
We will start the chapter by describing these services and setting the scene with regard to the standardization activities around them. Then we will focus on the presence service, explaining the abstract presence model and how it is materialized with SIP. We will also touch upon the presence data format and other topics such as resource lists and the utilization of the XCAP protocol.
Then we will present the instant messaging service and the two different ...