Dependable Information Service for Distributed Systems

A notion of a Dependable Information Service (DIS) is advocated as the means for applications in large scale distributed systems to select service instances meeting their requirements, functional as well as non-functional. Applications that need to provide certain correctness of results to the end user can only do so by requiring the services they use to guarantee particular level of correctness. When no such guarantees can be made, applications cannot provide the service and thus become unavailable. A system model is proposed to let applications temporarily accept lower correctness of used services in order to increase the availability caused by application accepted tradeoff. The proposed Dependable Information Service provides applications with a set of services appropriate for their demands and informs them of changes that can affect their quality level.