of a merging tool. Section 5 shows the outcome of
our solution based on a exemplary use case. Finally,
Section 6 reflects and concludes the work.
2 FOUNDATIONS
This section describes the fundamentals concerning
business modeling, matching and merging.
2.1 Business Process Modeling
Languages
Process modeling is supposed to be an instrument for
coping with the complexity of process planing, with
importance for many purposes besides the develop-
ment of software (Becker et al., 2002). Business pro-
cess models help to improve and to re-engineer pro-
cesses. Vital for this purpose are models which help to
identify process weaknesses and allow an automated
comparison of new scenarios (Becker et al., 2003).
BPMN is a modeling language, using events and
activities to visualize (business-) processes. It descri-
bes the logic of process flows with the help of ga-
teway operators such as AND, OR and XOR
1
. Se-
quence flow, message flow and association elements
are used to describe the connection between certain
process objects (Kocian, 2011). In addition, swim-
lanes represent different roles, which allow to visu-
alize role-specific processes and their interdependen-
cies between each other in parallel.
Another prominent way of modeling processes is
Event-driven Process Chain (EPC). An EPC diagram
is a flowchart based diagram, used for resource plan-
ning and identifying possible improvements of a bu-
siness process (Object Management Group, 2016).
There are various other modeling techniques as well.
For the following explanations, we refer to the BPMN
2.0 standard.
2.2 Model Matching and Merging
In general, model matching and merging had already
been investigated in various modeling areas. For ex-
ample, (Brunet et al., 2006) show merging approa-
ches of entity relationship diagrams or state machi-
nes. Moreover, (Melnik, 2004) investigates the mat-
ching and merging of conceptual database schemata,
(Mandelin et al., 2006) proposes a technique for ma-
tching system architecture diagrams, using machine
learning and (Nejati et al., 2007) provide an approach
1
Exclusive or: True only, when one input is true and the
other is false.
for matching and merging statecharts specifications.
In general, (Brunet et al., 2006) describe model mer-
ging as an exploratory process, in which the goal is to
discover the exact nature of relationship between mo-
dels, as much as to combine them. Model merging is
facilitated by a number of related operations on mo-
dels, such as comparing, checking their consistency
and finding matches between them.
For our descriptions, we distinguish the operators
of matching and merging and refer to a business pro-
cess graph setting. Therefore, we use the following
definitions:
• A business process graph G is a set of pairs
of process model notes – each pair denoting
a direct edge. A node v of G is a tuple
(id
G
(v), λ
G
(v), τ
G
(v)) consisting of a unique iden-
tifier id
G
(v) within G, a label λ
G
(v) and a type
τ
G
(v) (La Rosa et al., 2013).
• Given process graphs G
1
, G
2
and nodes v ∈ G
1
,
w ∈ G
2
, process model matching is defined as
finding an injective mapping f (v, w) : v → w,
where f (v, w) is a scoring function and its value
is within the interval [0, 1] ⊂ R. This operation is
used to find commonalities between models (Bru-
net et al., 2006).
• Given n process graphs, process model merging
describes the reduction to k graphs (k < n), such
that the behavior and correctness is preserved.
In the specific field of interest of business pro-
cesses some valuable research has been done alre-
ady. (Kuester et al., 2008) suggest a process merging
tool that detects and resolves changes between pro-
cess models, which has limited applicability concer-
ning recent modeling languages. In addition, they fo-
cus more on the user-friendly design of their solution.
(La Rosa et al., 2013) provide a merging algorithm
for business process graphs. They explicitly abstract
from any specific notation, which increases the appli-
cability of the approach.
We base our studies on these findings and adapt
the algorithm correspondingly to our specific area of
interest.
3 APPROACH
We convert BPMN models to graphs. The approach
for merging the graphs consists of three main steps
(Figure 1):
1. Matching: Discovering similar parts of the graphs
and building a similarity map, which is passed on
to the next step.
Semi-automated Business Process Model Matching and Merging Considering Advanced Modeling Constraints
325