Keyword Search over Federated RDF Datasets

This paper describes an algorithm to perform keyword search over federated RDF datasets. The algorithm compiles keyword-based queries into federated SPARQL queries, without user intervention, under the assumption that the RDF datasets and the federation have a schema. The compilation process is explained in detail, including how to synthesize external joins between local queries, how to combine local queries with UNION clauses, and how to construct the WHERE and TARGET clauses. The paper then presents the architecture of a system that implements the algorithm. Finally, the paper describes experiments with three real-world datasets to validate the implementation and to help understand the different situations faced by the compilation process.