Data access services and automatic generation of cooperating interfaces

An important issue for the success of a database application is the effectiveness of its interface and frequently a relevant part of programming effort is devoted to the generation of interfaces. The visual programming environments reduce only partly this effort and in particular things become more complicated when data coming from different sources (different views in the same database or even views from different databases or systems) are to be related and must cooperate in the data access task. Our proposal is to define a new database access paradigm, called "service", including in itself the bare aspects of data access, such as browsing and selecting a tuple, and a compositional algebra for services, to automatically generate a comprehensive interface when separate services which were not designed for the cooperation, are combined. In addition, the architecture we adopt for the implementation of services is based on Java and JDBC. Services and combination of services expressed with the service algebra are automatically compiled into Java objects, allowing the rapid development of platform independent data access services. The paper formally introduces the notion of "service" with its semantics for data access; shows the compositional algebra for services and discusses a set of properties for this algebra which can be used when combining the components for simplification and optimization purposes, and describes the architecture for the implementation.