Supporting adaptive services in a heterogeneous mobile environment

Future computer environments will include mobile computers which will either be disconnected, weakly interconnected by low-speed wireless networks such as GSM (global system for mobile communications), or fully interconnected by high-speed networks ranging from Ethernet to ATM (asynchronous transfer mode). While the transition between networks is currently a heavyweight operation, we believe that developments in network interface technology will soon enable mobile computers to dynamically select their network service based on cost and performance requirements. Such flexibility, coupled with the inherent unreliability of mobile communications, means that system services and applications will be subject to rapid and massive fluctuations in the quality-of-service provided by their underlying communications infrastructure. In this paper, we discuss the design of a distributed systems platform to support the development of services which are able to tolerate this environment by dynamically adapting to changes in the available communications quality-of-service