On the structuring of distributed systems : the argument for mobility

The last decade has seen an explosion in the growth and use of the Internet. Rapidly evolving network and computer technology, coupled with the exponential growth of services and information available on the Internet, is heralding in a new era of ubiquitous computing. Hundreds of millions of people will soon have pervasive access to a huge amount of information, which they will be able to access through a plethora of diverse computational devices. These devices are no longer isolated number crunching machines; rather they are on our desks, on our wrists, in our clothes, embedded in our cars, phones and even washing machines. These computers are constantly communicating with each other via LANs, Intranets, the Internet, and through wireless networks, in which the size and topology of the network is constantly changing. Over this hardware substrate we are attempting to architect new types of distributed system, ones that are able to adapt to changing qualities and location of service. Traditional theories and techniques for building distributed systems are being challenged. In this new era of massively distributed computing we require new paradigms for building distributed systems. This thesis is concerned with how we structure distributed systems. In Part I, we trace the emergence and evolution of computing abstractions and build a philosophical argument supporting mobile code, contrasting it with traditional distribution abstractions. Further, we assert the belief that the abstractions used in traditional distributed systems are flawed, and are not suited to the underlying hardware substrate on which contemporary global networks are built. In Part U, we describe the experimental work and subsequent evaluation that constitutes the first steps taken to validate the arguments of Part I.