Query Templates for RDF Stream Processing

In recent years there has been a growing interest in using Semantic Web technologies to process streaming information, and several RDF Stream Processing (RSP) systems have been developed to bridge the gap between static and streaming Linked Data. However, the lack of a standardized query language makes testing and benchmarking of systems difficult, since queries need to be developed for each supported language in parallel. This process is both time consuming and error prone. The RDF Stream Processing W3C Community Group is currently working towards a standardized query language for RSP (RSP-QL). This paper proposes an extension to the SPIN Modeling Vocabulary to support the representation of RSP-QL queries as RDF. The vocabulary provides mechanisms to capture queries as parameterized templates that can be shared and queried using standard Semantic Web technologies. The vocabulary is query language agnostic, and we demonstrate how different serializations (CQELS, SPARQLstream, and C-SPARQL) can be supported by modeling the queries of the CSRBench benchmark as a single set of RSP-QL queries. We also show some of the language features that are currently only supported in RSP-QL, and discuss some additional features that the SPIN extension might offer. We argue that templates increase the flexibility and re-usability of queries, and by extension we believe that this can help in the more general adoptation of RSP technologies.