There has been significant recent interest in exploring the role of coordination languages as middleware for distributed systems. These languages provide operations that allow processes to dynamically and atomically access and manipulate collections of shared data. The need to impose discipline on the manner in which these operations occur becomes paramount if we wish to reason about correctness in the presence of increased program complexity. Transactions provide strong serialization guarantees that allow us to reason about programs in terms of higher-level units of abstraction rather than lower-level data structures. In this paper, we explore the role of an optimistic transactional facility for a Linda-like coordination language, We provide a semantics for a transactional coordination calculus and state a soundness result for this semantics. Our use of an optimistic concurrency protocol distinguishes this work from previous efforts such as Javaspaces, and enables scalable, deadlock-free implementations.
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