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

7.9 INSTANT MESSAGING (IM) PROTOCOLS

We shall briefly discuss these protocols because they are used in mobile services, but not central to a wide range of mobile applications; particularly, as they were all designed initially with only one application in mind, which is Instant Messaging, or IM. To go into the details of how these protocols work would be too detailed for this book, so instead we introduce the protocols, their backgrounds, uses and relationships. This is a useful grounding for those not familiar with the protocols for mobile IM, which, at times, can appear very confusing to the uninitiated. At the time of writing, there are three industry-wide open standards for implementing IM services. These are

1. SIP/SIMPLE
2. XMPP
3. IMPS

An overview of these standards and their applicability to the mobile environment is now given in the following subsections.

7.9.1 SIP/SIMPLE

SIMPLE stands for SIP for Instant Messaging and Presence Leveraging Extensions. This standard is the activity of an IETF working group (‘SIMPLE WG’). Their charter is available online and they summarise it thus:

This working group focuses on the application of the Session Initiation Protocol (SIP, RFC 3261) to the suite of services collectively known as instant messaging and presence (IMP). The IETF has committed to producing an interoperable standard for these services compliant to the requirements for IM outlined in RFC 2779 (including the security and privacy requirements there) and in the Common Presence ...