Querying the Deep Web
- Speaker: Dr. Andrea Cali, Department of Computer Science and Information Systems, Birkbeck, University of London
- Date: Wednesday, 9 March 2011 from 16:45
- Location: Room 745, Malet Street building
The term Deep Web refers to the data content that is created dynamically as the result of a specific search on the Web. In this respect, such content resides outside web pages, and is only accessible through interaction with the web site - typically via HTML forms. Usually, data sources accessible through web forms are modeled by relations that require certain fields to be selected - i.e., some fields in the form need to be filled in. These requirements are commonly referred to as access limitations in that access to data can only take place according to given patterns. In such context, computing the answer to a user query cannot be done as in a traditional database; instead, a query plan is needed that provides the best answer possible while complying with the access limitations. In this talk, we illustrate the semantics of answers to queries over data sources under access limitations and present techniques for query answering in this context. We show different algorithms to optimize query answering both at the time of the query plan generation and at the time of the execution of the query plan.