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

5.10 REAL-TIME SERVICES

Although the Web has been the dominant force behind the explosive growth of the Internet, HTTP is not the only Internet Protocol (IP) out there. For some types of application, especially those more sensitive to pushing lots of information across the network in a time-sensitive manner (i.e. real time), other protocols are important. In this section, we look at some key protocols and paradigms for real-time interaction using the Internet.

5.10.1 Multimedia Streaming

Thus far, our view of the Web has suggested a fixation with a page-request model as the dominant application model, whether the page be constructed from HTML or, as we have just discussed, a ‘page’ of XML²⁷. Additionally, it seems that we are primarily interested in pulling down chunks of information one page at a time, doing something with them (such as reading or further processing by our application) and then requesting some more.

Depending on the availability of resources within the entire Web infrastructure at any one point in time, we might expect variable performance in the infrastructure responding to page requests, most likely on a user-by-user basis. Perhaps a server gets busy, or perhaps a communications pathway is heavily congested, or perhaps a backend database server is busy doing a computationally intensive task, such as indexing a database. During such times, page responses might be slow. This will lead to variable performance. For example, we might get a page returned within two ...