An Active Blackboard for Service Discovery, Composition and Execution

George Lepouras, Costas Vassilakis, Anya Sotiropoulou, Dimitrios Theotokis, Akrivi Katifori
International Journal of e-Government

Organisations nowadays are in the process of developing network-enabled systems through which they deliver electronic services to citizens, customers and enterprises. Often, such services need to be combined in order to cover all aspects of a service consumer¢s life event. The composition of different services though is usually left to the service consumer, who needs to manually locate the individual services and drive the process of obtaining results from some services and feeding them as input to subsequent ones until all relevant services have been executed. Although it would be possible for organisations to improve their level of service through provision of composite services, realizing thus the concept of one-stop government, i.e. by making available mechanisms that would undertake the task of input collection, invocation and execution synchronisation of individual services and delivery of the final result as a reply, such facilities have not been made yet widely available. This shortage stems partly from financial considerations, since the frequent changes in the regulatory framework of both the individual services and in their interoperation requirements or in the technical aspects of the service implementation render the development and maintenance of composite services inexpedient and partly from technical issues, since format or representational incompatibilities in parameters and results hinders automation developments. In this paper we present an active blackboard architecture, which automates the task of service composition based on the semantics of individual services and the data dependencies between them. The blackboard incorporates registries, which can be employed for facilitating service discovery and an execution engine that arranges for dynamic service composition and execution.

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