Detecting Mutual Consistency of Shared Objects

In systems that support disconnected operations, shared objects must be cached at client sites to ensure that the objects are accessible while the client is disconnected. It is desirable that objects cached at a client site are mutually consistent with respect to the level of consistency provided by the system. We present a new technique for detecting mutual consistency of objects and show how it can be used to support causal consistency, which is appropriate in systems that support disconnected operations. 1 Introduction In distributed systems, objects stored in shared repositories need to be cached at sites where they are frequently accessed to combat high latency and to reduce communication costs. Such caching is essential in systems that support disconnected operation because a client cannot access objects from shared servers during the periods when it is disconnected. The Coda file system [8] is an example of a system where client caching is used both to improve performance and ..