Contextual computing has been around for several years with a variety of names such as pervasive computation and omnipresent computing. Recently there has been a drive toward making personal digital assistants (PDAs) more aware of their environment. For example, a cell phone may sense that it is in a conference room and reason that it should divert calls to voice mail. In conjunction with this trend, there has also been an equally significant trend toward peer-to-peer (P2P) distribution of information, in which an unprecedented number of people can have access to information.

While considering these trends, the concept of context-sensitive computation developed. The initial idea was that information would drive the type of processing that was done on it instead of the traditional model of systems and software being static in the way they process information. The idea for this book was born from merging this concept with those of pervasive computation, peer-based hyper–data distribution, and global access to information. Thus the idea of contextual computation was born.

To the best of our knowledge this idea is seminal, borrowing from a number of areas of computer science including sensors, information systems, logic, security, graphics, networks, and mathematics. This book presents a comprehensive model for how a contextually based processing system might be constructed. It discusses the components of such a system, the interactions of the components, key mathematical foundations behind the model, and brand-new concepts that are necessary to make such a system operate.

Because the idea of contextually driven processing is comprehensive, it is a very large idea. Anyone from a developer to a company to researchers and government entities may want to borrow parts of the model or design entire systems based on the concepts developed in this book.