Space-based computing middleware offers a data driven style for the coordination of processes. The interaction requirements between these processes can be complex, and the template matching coordination law of the Linda and JavaSpaces model is not sufficient. Moreover, the usage should not be limited to a single platform. Several authors have proposed coordination extensions, but besides the suggestion to use XML or RDF based query facilities, a formalization of a general and extensible space-based coordination model has not yet been realized. In this paper we present the algebraic data structures and the coordination model based on a navigational query language for the extensible virtual shared memory architecture, and show how they can be adapted to support arbitrary coordination laws by the introduction of user-definable matchmaker and selector functions. The platform independence is achieved through a language independent communication protocol. The formal specification of the data model is the necessary basis for this protocol.

Abstract. Modern distributed software systems must integrate in neartime parallel processes and heterogeneous information sources provided by active, autonomous software systems. Such lively information sources are e.g. sensory data, weather data, traffic data, or booking data, operated by independent distributed sites. The complex integration requires the coordination of these data flows to guarantee consistent global semantics. Design, implementation, analysis and control of distributed concurrent systems are notoriously complex tasks. Petri Nets are widely used to model concurrent activities. However, a higher-level programming abstraction is needed. We propose a new programming model for modeling concurrent coordination patterns, which is based on the idea of "peer workers" that represent re-usable coordination and application components. These components encapsulate behavior, structure distributed data and control flow, and allow integration of pre-existing service functions. A domain-specific language is presented. The usability of the peerbased programming model is evaluated with the Split/Join pattern.

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