Service Oriented Computing (SOC) is a paradigm for building new software applications from existing loosely-coupled services. During service composition, services available to play different roles in a composition may have variations in their business-level protocols. These protocols may involve communication between two services in a point-to-point relationship, or communication among more than two services. Furthermore, as the business processes change, those protocols need to be modified to reflect the changes. In this paper, we propose a method to describe protocols between roles that services will play in the composition by specifying the temporal constraints. An automated aggregation of those protocols is then carried out to produce role-centric views. Protocol compatibility of available services can then be checked against these views. We will show how our approach supports the incremental specification of protocols and the flexibility of changing protocols.