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1 Introduction 7
the business process level. This information can be used to automatically discover
models based on frequent patterns. Moreover, if a model is given, then the con-
formance of the process with respect to this model can be measured. The latter is
interesting when analyzing compliance and process flexibility. Both conformance
checking and process discovery are part of the process mining domain.

1.3 BPM Standard Approaches

Over the years, there have been many approaches toward the specification of busi-
ness processes. Many BPM tools supported their own languages and it was often
unclear how these languages compared. Over time a number of standards and/or
widely used approaches emerged, and we will briefly look at some of the more
important ones in this section.
One of the first attempts to define a standard approach to the specification of exe-
cutable business processes was the XML Process Definition Language (XPDL) 1.0,
defined in the nineties by the Workflow Management Coalition (WfMC), an indus-
try body promoting the spread and further development of workflow technology.
XPDL was intended to facilitate interoperability between workflow environments.
The language offered a minimal set of generally occurring routing constructs such
as various splits and joins, and these were defined in natural language. Due to this
minimalist approach and to the fact that various interpretations of even these basic
constructs was possible, the goal of interoperability was not achieved and gradually
XPDL 1.0 became irrelevant.
In 2003, the Business Process Execution Language (BPEL) was proposed. This
language combined Microsoft’s XLANG and IBM’s Web Services Flow Language
(WSFL) and is therefore a language that marries two fundamentally different
approaches to the specification of executable business processes. Generally speak-
ing, BPEL is a block-structured language where business processes are specified in
terms of self-contained blocks that are composed to form larger, more complex,
blocks. However, BPEL is not fully block-structured as it supports the specifi-
cation of dependencies that cross block boundaries through the use of so-called
control links. While BPEL was a clear step forward in terms of its support for
the specification of control-flow dependencies, the language provided no support
for the involvement of human participants in the execution of business activities.
In addition, the language has no graphical representation; specifications have an
XML-based depiction.
The Business Process Modeling Notation (BPMN) was introduced to provide
an easily understood graphical notation that could serve as a front end to var-
ious approaches for the execution of business processes. The language itself is
not intended to be directly executable, rather specifications are expected to be
transformed to an executable language to achieve their enactment. BPMN pro-
vides fairly strong support for the specification of control-flow dependencies and
is graph-structured rather than block-structured. Contrary to BPEL, BPMN imposes