Failure recovery in wireless computing environments
Abstract
This thesis investigates failure recovery techniques for distributed applications in wireless LANs and cellular networks. The limitations on available network bandwidth, battery power and lack of stable storage for notebook computers and hand-held de vices make traditional failure recovery protocols not readily applicable to wireless environments. In addition, hand-held devices typically have slow processors and limited amount of memory, that make it difficult to implement failure recovery for applications running on these devices. A protocol for failure recovery in wireless LANs using message logging is developed in this thesis. In this approach, foreign agents log messages at base stations for applications running on mobile hosts. In contrast to existing wireless recovery protocols, failure of a mobile host does not affect processes on other mobile hosts and recovery is independent. Proxy-based recovery, where application layer proxies provide failure recovery for the client side of three-tier applications on cellular networks, is also presented. In case of a client failure, the proxy can recover the client using its local copy of the client's state and message logs, without any assistance from the server. Experiments and simulations show that both of the protocols have similar failure free runtime performance as compared to existing protocols and achieve faster recovery time. To facilitate failure recovery on mobile hosts, a user-directed and a transparent checkpoint library for Windows 2000 operating system has also been developed. The checkpoint libraries described in the Appendix can be combined with the message logging protocols presented in this thesis to recover multi-threaded client programs.
Degree
Ph.D.
Advisors
Fuchs, Purdue University.
Subject Area
Computer science
Off-Campus Purdue Users:
To access this dissertation, please log in to our
proxy server.