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Software r ejuvenation is the concept of gracefully terminating an application and immediately restarting it at a clean internal state. In a client-server type o f application where the server is intended to run perpetually for providing a service to its clients, rejuvenating the server process periodically during the most idle time of the server increases(More)
The presence of physical obstacles and radio interference results in the so called " shadow regions " in wireless networks. When a mobile station roams into a shadow region , it loses its network connectivity. In cellular networks, in order to minimize the connection unreliability, careful cell planning is required to prevent the occurrance of the shadow(More)
Nondeterminism is one of the most elusive concepts in computing. In this paper we direct our efforts towards viewing nondeterminism as an additional resource at the disposal of time or space bounded Turing machine computations and study the classes of languages acceptable by these machines with <underline>restricted</underline> amounts of nondeterminism. (More)
With the explosive growth of the World Wide Web, some popular Web sites are getting thousands of hits per second. As a result, clients (browsers) experience slow response times and sometimes may not be able to access some Web sites at all. Upgrading the server nodes to more powerful machines may not always be cost-effective. A natural solution is to deploy(More)
Over the last 30 years or so many results have appeared on the descriptional complexity of machines with limited resources. Since these results have appeared in a variety of different contexts, our goal here is to provide a survey of these results. Particular emphasis is put on limiting resources (e.g., nondeterminism, ambiguity, lookahead, etc.) for(More)
Process replication is provided as the central mechanism for application level software fault tolerance in SwiFT and DOORS. These technologies, implemented as reusable software modules, support cold and warm schemes of passive replication. The choice of a scheme for a particular application is based on its availability and performance requirements. In this(More)
This paper describes our experience with the implementation and applications of the Unix checkpointing library libckp, and identifies two concepts that have proven to be the key to making checkpointing a powerful tool. First, including all persistent state, i.e., user files, as part of the process state that can be checkpointed and recovered provides a(More)