Service-Oriented Systems Engineering: Specification and Design of Services and Layered Architectures

Abstract

Based on the Focus theory of distributed systems (see [Broy and Stolen, 2001]) that are composed of interacting components we introduce a formal model of services and of layered architectures. In FOCUS a component is a total behavior. In contrast, a service is a partial behavior. A layer in a layered architecture is a component or a service with two service interfaces, an import and an export interface. A layered architecture is a stack of several layers. For this model of services and service layers we work out specification and design techniques for layers and layered architectures. We study the application of the notions of a service and service layer and its relation to object orientation. Finally we discuss more specific aspects of layered architectures such as refinement and error handling as well as layer models in telecommunication.