Most consumers do not simply appreciate technology for technology's sake. They want to know what the technology can do for them. You give them a new gadget and they ask, "What is this device good for?" Our example family of the future from Chapter 1, Alice, Bob, Charles, and Diana, would probably represent this type of consumer. Indeed, although the focus of most of this book is the underlying networking technology that enables services and applications to be provided on wireless IP networks, it is the services and applications that will drive the commercial success of the technologies.

As explained in Chapter 1, the focus of this book is on the network layer aspects (and some link-layer aspects) of wireless Internet telecommunications. Thus, we only briefly discuss application development and execution environments for wireless IP services. Instead, we focus on going from the main coverage of the book the network layer to the closely related topic of middleware to abstract network capabilities and present them to application developers. In particular, among the exciting developments in such middleware is OSA, which is being developed by 3GPP and the Parlay Group, in Section 10.2. Implementation of these application program interfaces (APIs) is beyond our scope in this book, but I hope to convey the essence of the ideas even to readers who are not programmers. Since OSA is more focused on the network infrastructure part of the network, more terminal-centric technologies will be considered in Section 10.3.