Approximate XQuery Reformulation Based on GLAV Mapping and Unification

The mediation is based on an essential component called mediator. The main role of the mediator is to reformulate a user query, written in terms of global schema, in queries written in terms of sources schemas. This paper describes an algorithm for reformulation of XQuery queries. The algorithm is based on the principle of logical equivalence, simple and complex unification, to obtain a better reformulation. It takes as parameter the query XQuery, the global schema (written in XMLSchema), mappings GLAV and gives as a result a query written in terms of sources schemas. The results of implementation show the proper functioning of the algorithm.