SWRL is an expressive OWL-based rule language that can be used to increase the amount of knowledge encoded in OWL ontologies. While semantically a SWRL rule can be considered as an additional type of OWL axiom, the authoring and management of SWRL rule bases requires specialized tools that are not typically present in standard OWL development environments. In this paper, we describe such a tool—called the SWRLAPI—that provides a rich development environment for working with SWRL rules. The SWRLAPI is built on the widely-used Protégé-OWL ontology toolkit. It provides both a set of highly interactive user interfaces for working with rules and a set of low-level APIs for embedding rules in knowledge-driven applications. This SWRLAPI has been used to develop a number of technologies to support data integration on the Semantic Web, including a SWRL-based query language called SQWRL and a set of tools that support interoperation between OWL and a variety of information formats.
