Abstract:
Workflow management systems (WFMSs) are only applicable in a secure and safe
manner if the business process (BP) to be supported is well-structured and
there is no need for ad hoc deviations at
run-time. As only few BPs are static
in this
sense, this significantly limits the applicability of current workflow
(WF) technology. On the other hand, to support dynamic deviations from
premodeled task sequences must not mean that the
responsibility for the
avoidance of consistency
problems and run-time errors is now completely shifted
to the (naive) end user. In this paper we present a formal foundation for the
support of dynamic structural changes of running WF
instances.
Based upon a formal WF model (ADEPT), we
define a complete and minimal set of change
operations (ADEPTflex) that support users in modifying the structure of a
running WF, while maintaining its (structural) correctness and
consistency.
The correctness properties defined by ADEPT are
used to determine whether a
specific change can be applied to a given WF instance or not. If these
properties are violated, the change is either rejected or the correctness must
be restored by
handling the exceptions resulting from the
change. We discuss
basic issues with respect to the management of changes and the undoing of
temporary changes at the instance level. Recently we have started the design
and implementation of
ADEPTworkflow, the ADEPT workflow engine, which
will make
use of the change facilities presented in this paper.
Keywords: Workflow Management, Exception Handling, Dynamic Change, Adaptive Workflows
Contact: reichert@informatik.uni-ulm.de