Abstract
A semantic application typically is a heterogenous system of interconnected components, most notably a reasoner. OWLlink is an implementation-neutral protocol for communication between OWL 2 components, published as a W3C Member Submission. It specifies how to manage reasoning engines and their Knowledge Bases, how to assert axioms, and how to query inference results. A key feature of OWLlink is its extensibility, which allows the addition of required functionality to the protocol. We introduce the OWLlink structural specification as well as three bindings which use HTTP as concrete transport protocol for exchanging OWLlink messages rendered according to selected OWL 2 syntaxes. Finally, we report on existing APIs, reasoners and applications that implement OWLlink.