Marek Lehmann

Conformance Test of Federated Choreographies

Web Services technology is constantly gaining importance for automation of business processes. A major contribution of this technology is its integration capability, i.e. compositions allowing several autonomous but cooperating web services to implement a business process going beyond the boundaries of a single organization. Federated choreographies provide a framework for modular modeling complex collections of choreographies and orchestrations. In this paper we present a conformance test to check the structural conformance of the choreographies and orchestration of the proposed model in order to hold the model structurally consistent. We can formally check whether an orchestration realizing (one part of) a choreography, resp. two related choreographies fit together.

Uniform Access to Data in Workflows

Data aspects in workflow systems did not yet receive the same attention as process aspects. Various kinds of data are processed in workflow system: from case data to process data, from internal data to access to external databases or document exchanges in inter-organizational workflows. We propose a uniform treatment of all kinds of data in workflow definition and provide abstraction mechanism which allow transparent access to all kinds of data in a uniform way. We use XML as data access language in our workflow definition language WDL-X. The concept contributes to transparency of data location and logical and physical data independence of workflow systems. It facilitates the reuse of predefined activities and subworkflows on different data sets and eases the interaction of a workflow with its environment by abstracting from the actual representation of data.

Synchronizing copies of external data in workflow management systems

Workflow management systems integrate applications and data resources in business processes. Frequently they have to keep local copies of data in the so called workflow repository. We introduce and define synchronization policies for these copies with their external data sources ranging from the provision of fully synchronized replications of external data sources to unsynchronized storage of read results. We analyze in detail the effects of combining various pull and push policies and show in an example how these policies can be used in different situations.

Workflow data guards

Workflow management systems (WfMSs) frequently use data to coordinate the execution of workflow instances. A WfMS evaluates conditions defined on data to make the control flow decisions i.e. selecting the next activity or deciding on an actor. However, data – within and outside of a running workflow instance – may change dynamically. Modifications of data needed for past control flow decisions may invalidate these decisions. We analyze the desired synchronization policies, and propose a mechanism called data guard to selectively guarantee that significant changes in data are recognized and handled by the data management system to ensure correctness of workflow execution in face of asynchronous updates.

Uniform and Flexible Data Management in Workflow Management Systems

Various kinds of data are processed in workflow management systems: from case data to control data, from internal data to access to external databases or documents exchanged in inter-organizational workflows. We propose a uniform treatment of all kinds of business data in workflows. This is achieved by an abstraction mechanism which enables the transparent access to data in any source in a uniform way. Moreover, we ensure simplicity by binding the human user interface layer of the workflow system with XML-based forms. The concept contributes to transparency of data location, and logical and physical independence of data, business logic and presentation in workflow systems. It facilitates the reuse of predefined activities and forms on different data sets and eases the interaction of a workflow with its environment by abstracting from the actual representation of data.