Service-oriented computing (SOC) has emerged as the eminent market environment for sharing and reusing service-centric capabilities. The underpinning for an organization 's use of SOC techniques is the ability to discover and compose Web services. Although industry approaches to composition have a strong notion of business processes, these approaches largely use syntactic descriptions. As such composition is limited since the true functionality of ambiguous service operations cannot be inferred. Alternatively, academia uses semantic approaches to disambiguate services, but, at the same time, most of these approaches neglect the process rigor needed for complex compositions. In this paper we present a generalized semantics-based technique for automatic service composition that combines the rigor of process-oriented composition with the descriptive-ness of semantics. Our generalized approach extends the common practice of linearly linked services by introducing the use of a conditional directed acyclic graph (DAG) where complex interactions, containing control flow, information flow and pre/post conditions, are effectively represented. Furthermore, the composition can be represented semantically as OWL-S documents. Our contributions are applied for automatic workflow generation in context of the currently important bioinformatics domain.