Design of Adaptive Distributed Systems by Protocol Switching

Abstract

Adaptation is a desirable feature of any distributed system as it helps the system perform gracefully under different environments. In some cases, adaptation is required to ensure correct behavior of the system under different environments. In other cases, adaptation is used to ensure better performance when the environment changes. Any adaptive distributed system generally has two components. The first one is the monitoring part that monitors the state of the environment. The second component actually enables the adaptation by employing some mechanism. In this thesis we focus on mechanisms for enabling adaptation in distributed systems. For many problems, more than one protocol exists such that each protocol works better in some specific environment. In such cases, adaptation can be achieved by dynamically switching between the protocols as the environment changes. However, in many cases it is also important to maintain certain properties of the system while switching from one protocol to another. In this thesis, we illustrate protocol-switching based adaptation in distributed systems by designing adaptive protocols for the single source broadcast and the mutual exclusion problems. In both cases, some guarantees on the performance of the system are provided even in the presence of switching.