The inherent limitations of mobile devices necessitate information to be delivered to mobile clients to be highly personalized according to their profiles. This information may be coming from a variety of resources like Web servers, company intranets, email servers. A critical issue for such systems is scalability, that is, the performance of the system should be in acceptable limits when the number of users increases dramatically. Another important issue is being able to express highly

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... ized information in the user profiles which requires a querying power as that of SQL on relational databases. Finally, the results should be customized according to user needs and preferences. Since the queries will be executed on the documents fetched over the Internet, it is natural to expect the documents to be XML documents.