Wildcards for lightweight information integration in virtual desktops

We present a flexible information integration approach which addresses the dynamic integration needs in a personal desktop environment where only partial mappings are defined between the sources to be integrated. Our approach is based on query rewriting using substitution rules. In addition to exploiting defined mappings, we employ substitution strategies, which are inspired by the idea of using wildcards in querying and filtering tasks. Starting from a triple based query language as used for querying RDF data, unmapped ontological elements are substituted in a controlled way with variables, leading to a controlled form of query relaxation. In addition, the approach also provides evidences for refining the existing mapping based on the results of executing the relaxed queries. Different strategies for replacing nonmatched ontology elements with variables are presented and evaluated over real-world data sets.