Towards Extensible Information Brokers Based on XML

The exponential growth in the number and size of information services available on the internet has created an urgent need for information agents which act as brokers in that they can autonomously search, gather and integrate information on behalf of a user. Moreover, the inherent volatility of the internet and the wide range of information processing tasks to be carried out, calls for a framework that facilitates both the construction and evolution of such information brokers. This paper proposes such a framework named XIB (extensible Information Brokers). Based on descriptions of relevant information services, XIB supports the interactive generation of an integrated query interface, generates wrappers for each information service dynamically, and returns to the user the composed result to a query. XIB depends heavily on XML-related techniques. More specifically, we will use DTDs to model the input and output of the service, use XML elements to denote the input and output values. By using this representation, service integration is investigated in the form of DTD integration, and query decomposition is studied in the form of XML element decomposition. Within the proposed framework, it is easy to add or remove information services on the internet to a broker, thereby facilitating maintenance, evolution and customization.