Semantic Grid is becoming a key enabler for next generation Grid and the need of supporting process description and enactment, by means of composition of multiple resources, emerged as one of the fundamental requirements. Within NextGRID1 project, the idea of adopting business processes (expressed as workflow policies) as architectural components in a next generation Grid has been developed with the aim of providing architecture with dynamic behaviour and interoperability.

The need of a semantic workflow representation language then emerged and was developed defining an OWL-S extension able to support workflow description. The resulting OWL-WS (OWL for Workflow and Services) ontology allows us modelling concept like abstract and concrete services and workflows according to a Semantic Workflow Model also enabling specification of higher-order workflows and semantic service grouping. This language is being used for specifying adaptive business processes (policy) that are used as evaluation and binding mechanisms by a Workflow Enactment Engine.