Backed by the flexibility of the RDF data model, and consisting of both a query language and data access protocol SPARQL has the potential to become a key component in Web 2.0 applications. SPARQL could provide a common query language for all Web 2.0 applications.

Developing and enhancing a web service API involves dealing with the conflicting needs of end users. The push towards ever finer grained access to data must be balanced against the performance and efficiency costs of returning redundant data. By supporting a query end-point a service may let clients effectively design their own API, with corresponding performance improvements.

This paper will review the SPARQL specifications and its potential benefits to Web 2.0 applications. Focusing on the SPARQL protocol for RDF, the paper will provide implementation guidance for developers interested in adding SPARQL support to their applications.

Issues such as mapping existing data sources onto the RDF model will be introduced alongside other fundamental concerns such as efficiency and security.

Trivial, but useful extensions to the SPARQL protocol, including multiple output options, and integration with AJAX applications will also be demonstrated.

Drawing on services (e.g. GovTrack, Opera Community) that already support SPARQL querying, the examples used in this paper will be grounded in real deployed applications and services.