In this thesis we look at issues in workflow interoperability analysis, formal modelling, transformation and architecting of cross-organisational workflows. We target these problem areas through the identification of a taxonomy of workflow interoperability aspects that influence formal modelling in which we propose an approach that incorporates privacy requirements of the involved individual workflows. We propose transformation operators that allow for the re-use and case-specific application of existing legacy workflows. On this basis we discuss aspects that influence a supporting architecture for cross-organisational workflows and specifically investigate in stateful communication between the entities of our proposed workflow model.
To identify real issues for research in the field of collaborative business processes we discuss complexity of collaborative workflows. We introduce six dimensions of interoperability aspects and apply them to scenarios. These dimensions are: Enactment and Invocation, Request-to-Task Ratio, Request with/without Response, Interdependency, Ownership, and Request-to-Response Ratio.
On the basis of the workflow analysis we introduce a three-tier distributed process model consisting of private, view and coalition workflow tier. We argue how this model allows for privacy of the involved private workflows, whilst providing flexibility through workflow views. We introduce a formal model that is based on digraphs and adjacent matrices and investigate into transformation operators to obtain workflow views from private workflows (generalisation) and vice versa (specialisation), how to compose workflow views into coalition workflows (expansion) and how to decompose them again (reduction).
We extend the concept of electronic services through the notion of process pages and present the entity types and the attributes of a "minimal" cross-organisation workflow meta-model that is sufficient for querying, monitoring and verifying coalition, view, and private processes and serve as blueprint for their evolution and maintenance.
On the basis of architectural considerations we develop a collaborative workflow architecture (CWA). CWA is a service-oriented architecture that embraces service providers, service consumers, and service repositories. Its concepts are valid for mediated and peer-to-peer interactions and express no choice of a particular underlying technology. In CWA we demonstrated how a security concept, such as public key infrastructure can be incorporated without limiting the flexibility of the architecture.
One of our main foci in the architecture are communication aspects in terms of state-dependencies and explicit modelling. We propose that private workflows and workflow views should be tightly coupled through state dependencies, whilst workflow views should be coupled through synchronisation tasks. We introduce a Petri- Net-based state transition approach that binds the states of private workflow tasks to their adjacent view-task.