Chapter 9. Session Description

In this chapter, we will look at how multimedia sessions can be described. First we will explain the need for describing sessions and list some examples of scenarios in which sessions need to be described. Then we will focus on the Session Description Protocol, which defines the syntax for describing multimedia sessions. After that, the SDP offer/answer model will be explained. It describes a procedure for the exchange of session descriptions between communicating parties that is crucial for enabling IP multimedia communication services. We will also show how SDP is used in some particular IP communication scenarios.

Once the theory has been presented, we will also include an SDP programming section that shows the reader how to programmatically build and parse session descriptions. As part of this section, we will build a simple Java component that will be reused in our soft-phone project in Chapter 12.