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Technical Report

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Technical Report Number



The term shared dataspace refers to the general class of models and languages in which the principal means of communication is a common, content-addressable data structure called a dataspace. Swarm is a simple language we have used as a vehicle for the investigation of the shared dataspace approach to concurrent computation. It is the first shared dataspace language to have an associated assertional-style proof system. An important feature of Swarm is its ability to bring a variety of programming paradigms under a single, unified model. In a series of related examples we explore Swarm's capacity to express shared-variable, message-passing, and rule-based computations; to specify synchronous and asynchronous processing models; and to accommodate highly dynamic program and data structures. Several illustrations make use of a programming construct unique to Swarm, the synchrony relation, and explain how this feature can be used to construct dynamically structured, partially synchronous computation. The paper has three parts: an overview the Swarm programming notation, an examination of Swarm programming strategies via a series of related example programs, and a discussion of the distinctive features of the shared dataspace model. A formal operational model for Swarm is presented in an appendix.


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