This paper proposes a pattern-based service collaboration architecture using services as building blocks in a service-oriented architecture (SOA). In this architecture, service registry is used to obtain the metadata of services and collaboration patterns. Thus, not only services, but also collaboration patterns can be reused. However, dynamic collaboration requires a measure to verify and validate such a dynamic process at the meta-control level. This paper presents a policybased infrastructure to dynamically verify and control the collaboration process in SOA.