Algebraic Service Specification and Rule Generation for Integrating Multiple Dissemination-Based Information Sources

Integration of heterogeneous information sources has been one of important data engineering research issues. Various types of information sources are available today. They include dissemination-based information sources, which actively and autonomously deliver information from server sites to users. We have been developing a mediatodwrapper-based information integration system, in which we employ ECA rules to enable users to dejine new information delivery services integrating multiple existing dissemination-based information sources. However; it is not easy for users to directly specihl ECA rules and to verifj, them. In this paper; we propose a scheme to spec& new information delivery services using the framework of the relational algebra. We discuss some important properties of the speciJication, and show how we can derive ECA rules to implenient the delivery services.