Web Services Modeling Language

WSML or Web Service Modeling Language is a formal language that provides a syntax and semantics for the Web Service Modeling Ontology (WSMO).
In other words, the WSML provides means to formally describe the WSMO elements as Ontologies, Semantic Web services, Goals, and Mediators. 
The WSML is based on the logical formalisms as Description Logic, First-order Logic and Logic Programming.