Efficient Querying of Distributed RDF Sources in Mobile Settings based on a Source Index Model

Recent technological developments in the area of mobile devices in combination with the ubiquity of mobile connectivity have turned handheld devices into rich mobile web clients. On the other hand, we witness an increased number of web resources that are no longer only available in HTML but also in RDF format. In order to access relevant information in a mobile setting, we often want to query a subset of this large amount of heterogeneous RDF resources based on various context factors. We present a semantic technology-based client-side solution for efficient querying of large sets of distributed RDF sources without query endpoints. Our solution continuously extracts metadata from distributed RDF sources and manages this metadata in a local Source Index Model (SIM). When a new query has to be processed, the SIM is consulted to identify, assemble and query only potentially relevant resources. We do not plan to replace existing mobile query engines, but rather build on them to efficiently and transparently query large sets of distributed online RDF sources. The evaluation of our enhanced query handler reveals significant improvements in the overall query execution time based on the proposed SIM.