Handling of irregularities in human centered systems: a unified framework for data and processes

Abstract

Practical process-support and workflow systems should be built to describe the simple, normal flow of events and then deal easily with irregularities, including tolerating deviations. Similarly, these systems should describe the normal format and constraints concerning the large amounts of data that are usually stored, but then deal with abnormalities and possibly accommodate exceptional values. We offer a framework for treating both kinds of irregularities uniformly by using the notion of exception handling (with human agents as potential online exception handlers) and applying it to processes that have been reified as objects in classes with steps as attributes. As a result, only a small number of new constructs, which can be applied orthogonally, need to be introduced. Special runtime checks are used to deal with the consequences of permitting deviations from the norm to persist as violations of constraints. A logical semantics of process coordination and deviations is presented as a specification for implementations.