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13 The Business Process Modeling Notation 365
The STP BPMN modeler does not support certain features of BPMN. Specifi-
cally, it does not support the markers and properties for multiinstance activities and
ad-hoc activities. To overcome this limitation, the BPMN2YAWL tool is able to
detect special types of text annotations: one for multiinstance activities and one for
ad hoc activities. The text annotations for multiinstance activities include param-
eters for specifying minimum and maximum amount of instances to be started,
and number of instances that need to complete before proceeding (also called the
threshold).
In addition to these limitations imposed by the STP BPMN modeler, the trans-
formation tool is not able to map data aspects (properties) nor resource allocation
aspect (lanes and pools) that are described in this chapter. It also does not support
features of BPMN that are not relevant for execution purposes such as link events,
groups, associations, and text annotations (other than the special text annotations
for multiinstance and ad hoc activities mentioned above). Also, as the purpose of the
tool is to transform one BPMN diagram at a time (as opposed to a collection of inter-
acting BPMN diagrams comprising multiple pools), it does not take into account
message flows. Finally, the tool does not deal with advanced control-features that are
not covered in this chapter, such as complex gateways, compensation subprocesses,
and “compensate” events.
It is planned that the tool will in future be complemented by a reverse trans-
formation or a model co-evolution mechanism, in order to help developers who
modify a YAWL net produced by the BPMN2YAWL tool to propagate these changes
back to the BPMN diagram. This feature would allow business analysts working
with BPMN models and developers working with YAWL models to maintain their
models synchronized.
In addition to assisting in the transformation from high-level BPMN diagrams to
executable workflows in YAWL, the BPMN2YAWL tool, used in conjunction with
the WofYAWL component of the YAWL System, enables the analysis of BPMN
diagrams in order to detect deadlocks and other forms of unsafe behavior.

13.5 Summary

This chapter presents the Business Process Modeling Notation (BPMN). The BPMN
is a notation for modeling business processes at a more conceptual level as opposed
to a level at which the business process models can be executed directly by a work-
flow engine. At the conceptual level, business process models are used, among other
things, to facilitate communication between stakeholders, to analyze business prob-
lems by means of analysis or simulation of the models, and to serve as specifications
towards software development.
This chapter also presents the relation of BPMN process models to YAWL work-
flow models. The relation is described in such a way that automated transformation
of BPMN process models into YAWL models is possible. This is especially use-
ful when using BPMN models as a specification towards software development,
because it allows partial automation of the software development process to the