Integration of Web services into workflows through a multi-level schema architecture

Many organizations provide access to their workflows via Web interfaces, giving customers the opportunity to create and manipulate business cases interactively according to a predefined set of operations. Since enterprises can request such Web services in order to satisfy their business goals, it may be desirable for these enterprises to access Web services not only interactively, but to import and integrate them into their own workflow management systems and to invoke them from within workflow applications. There are several initiatives to standardize the specification of services in order to provide them to enterprises for import. Yet currently most providers of Web services do not support these specifications. Thus, requesting enterprises must extract the workflows and business objects behind the provided Web interface from the visible Web pages. This paper presents a design architecture for extracting the Web interface and the underlying workflows and business objects from a Web site in consecutive extraction phases, each phase resulting in a conceptual schema at one particular level in the architecture. The architecture satisfies service independence, i.e., changes in the Web interface do not require a complete redesign of the conceptual schemas, and level-specific integration, i.e., extracted Web services can be integrated at different design levels depending on the purpose of integration.