This paper presents a new approach for generating configured and flexible middleware systems for integration of heterogeneous and distributed data. The configuration is based on the selection of an adequate set of database services components and flexibility is achieved by adopting framework techniques. A control model checks the configuration, manages the communication between components and dynamically schedules tasks. The objective is to build tailored integration middleware systems, using a

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... minimum number of components. In addition, the use of framework allows for increased software quality and reduced development effort. Define Component QueryProceessing Offered-Operations parser(int id, string q-graph, int RC) re-writer(int id, string q-graph, string op-tree, int RC) optimizer(int id, string op-tree, string exec-tree, string result, int RC) Requested-Operations meta-data, get-object-MD (int id, string MD-type, string object-name, string o Communication, exec-subquery (int id, string DS-name, string subquery, st Communication, get-next-data (int id, string DS-name, string data, int RC) End-Component Define Workflow Select Operations QueryProcessing (parser); QueryProcessing (re-writer); QueryProcessing (optimizer); QueryProcessing(query-engine);