In this paper, we introduce an agent planner architecture which has the potential to execute composite models defined using various business process languages by means of a generic workflow model. By having a generic workflow model within an agent infrastructure, different composite process models as well as various agent programming paradigms including different planning languages can be executed on the same agent platform. To illustrate our ideas, we focus on the reduction of semantic web services to the workflow model. To explicate the reduction mechanism, we prefer to use OWL-S which is a widely known ontology for semantic services, since it provides rich workflow semantics by its process model ontology. Based on the given semantics of our workflow model and the transformation between OWL-S services and this workflow model, we give an algorithm to translate OWL-S service descriptions into the proposed workflow model.