Next Generation Wireless Applications: Creating Mobile Applications in a Web 2.0 and Mobile 2.0 World, 2nd Edition

14.11 SERVICE EXAMPLES

We shall now look at possible collaborative service examples in order to show the diverse and powerful capabilities of the IMS network.

14.11.1 Multimodal Chat

In this example, the incoming SIP messages are routed through all of the AS entities shown, which are a Presence server, an Instant Messaging (IM) server and a Push-To-Talk (PTT) server, as shown in Figure 14.14. Each server manages a separate service domain in its own right. However, let's examine a possible collaborative service example, in order to demonstrate the power of IMS and how AS entities can behave as service enablers.

Let us imagine an IM session with three users, A, B and C (dull names, but easy to reference). Users A and B are accessing the IMS framework via IM clients running on their PCs. A is on a WiFi-connected laptop in a coffee shop and B is at home on a cable modem. User C is connected via 3G, using a smart-phone device with integrated qwerty keyboard. Clearly, in this figure, we have multiple access technologies. Let us now examine some elements of the session. This is a complex collaboration at the SIP dialogue level, but we shall skip most of the detail in order to illustrate the concept (there are several ways to implement multimodal chat).

• Presence – Here, the presence state of each presentity is visible in each of the IMS clients. Let's call this generic presence-viewing client a ‘buddy browser’ (a topic we shall return to shortly). The buddy browser reveals:
  • User A – ...