THE IMS: IP Multimedia Concepts and Services, 3rd Edition

7

Messaging

There are currently many forms of messaging services available. In general, messaging entails sending a message from one entity to another. Messages can take many forms, include many types of data and be delivered in various ways. It is usual to have messages carry multimedia as well as text and be delivered either in near-real time as in many instant messaging systems or into a mailbox as in email today. In this chapter we give some details about messaging in the Internet Protocol Multimedia Subsystem (IMS) context.

7.1 Overview of IMS Messaging

Figure 7.1. reveals two different types of IMS messaging forms: immediate messaging and session-based messaging. Each form of IMS messaging has its own characteristics; so, even though messaging in its simplest form can be thought of as a single service – after all, all forms of messaging are really about sending a message from A to B – the fact that these characteristics differ makes them each a service on their own. However, the way in which applications are built on top of these services may well hide the fact that these are different forms of messaging. In fact, one of the key requirements for IMS messaging is easy interworking between different messaging types.

7.2 Immediate Messaging

Immediate messaging, or page-mode messaging, is the familiar instant messaging paradigm adopted in the IMS framework. It uses the Session Initiation Protocol (SIP) MESSAGE method to send messages between peers in near-real time. Figure 7.2 ...