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

2.4 APPLICATION TOPOLOGIES

In order to build services, we need to understand how applications might reside in the mobile ecosystem. There are two main planes of operation: client–server (CS) and peer-to-peer (P2P), and there is no reason why there can't be hybrids of the two – something we will look at later. Figure 2.4 shows the two planes of collaboration.

Notice that we have deliberately shown the user interface as a separate application component. The reasons for this will become clearer later, but it will help us to maintain a degree of focus on the user interface as an important and primary part of the applications domain. It also reminds us that the user interface and the actual bulk of the user-centred application could be running on separate devices within an interpersonal device network. Isolating the user interface in our model might also prompt us to consider more seriously the usability aspects of services and thereby give usability its due right on behalf of our end users. Regrettably, usability is often an afterthought.

If we focus on the CS plane for a moment, we notice that we are expecting the application to be in two parts. The server component of the application typically resides within the content network and we will appreciate that its essential role is to serve up content to the client on demand. However, we need to be aware that in mobile applications we have the possibility to push content to the client without demand. This latter scenario is what we call ...