We give a formal specification and an implementation for a partitionable group communication service in asynchronous distributed systems. Our specification is motivated by the requirements for building “partition-aware ” applications that can continue operating without blocking in multiple concurrent partitions and reconfigure themselves dynamically when partitions merge. The specified service guarantees liveness and excludes trivial solutions; it constitutes a useful basis for building realistic partition-aware applications; and it is implementable in practical asynchronous distributed systems where certain stability conditions hold.

AbstractÐWe give a formal specification and an implementation for a partitionable group communication service in asynchronous distributed systems. Our specification is motivated by the requirements for building ªpartition-awareº applications that can continue operating without blocking in multiple concurrent partitions and reconfigure themselves dynamically when partitions merge. The specified service guarantees liveness and excludes trivial solutions, it constitutes a useful basis for building realistic partition-aware applications, and it is implementable in practical asynchronous distributed systems where certain stability conditions hold.