Extensible information brokers

摘要

The number and size of information services available on the internet has been growing exponentially over the past few years. This growth has created an urgent need for information agents that act as brokers in the sense that they can autonomously search, gather, and integrate information on behalf of a user. To remain useful, such brokers will have to evolve throughout their lifetime to keep up with evolving and ever-changing information services. This paper proposes a framework named XIB (eXtensible Information Brokers) for building and evolving information brokers. The XIB takes as input a description of required information services and supports the interactive generation of an integrated query interactive. It also generates wrappers for each information service dynamically. Once the query interface and wrappers are in place, the user can specify a query and get back a result which integrates data from all wrapped information sources. The XIB depends heavily on XML-related techniques. More specifically, we use DTDs to model the input and output of each service, and XML to represent both input and output values. Based on such representations, the paper investigates service integration in the form of DTD integration, and studies query decomposition in the form of XML element decomposition. Within the proposed framework, it is easy to add or remove information services to a broker, thereby facilitating maintenance, evolution and customization of information brokers.