XSEarch: A Semantic Search Engine for XML

This chapter describes XSEarch, a semantic search engine for XML. XSEarch has a simple query language, suitable for a naive user. It returns semantically related document fragments that satisfy the user’s query. Query answers are ranked using extended information-retrieval techniques and are generated in an order similar to the ranking. Advanced indexing techniques were developed to facilitate efficient implementation of XSEarch. The performance of the different techniques as well as the recall and the precision were measured experimentally. These experiments indicate that XSEarch is efficient, scalable, and ranks quality results highly. Numerous query languages for XML have been developed. Recently, interest has arisen in techniques for “flexible querying” of XML. For example, the XQuery working group is considering how to add full-text search features and ranking to XQuery. Such capabilities have already been added to various XML query languages. It extends XML-QL with keyword search and presents performance experiments. XIRQL is an extension of XQL that supports vague predicates, weighting of terms, and minimal structural abstracting. XSEarch returns semantically related fragments, ranked by estimated relevance. The chapter concludes that XSEarch can be seen as a general framework for semantic searching in XML documents.