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D1
blocked
D1
created
D1
stored
created
A3
unblocked
blocked
A1
A2
A5
A4
stored
D1
unblocked
Fig. 3. Overview of the BP2OLC procedure
Besides, data objects are created within the BP instance that uses them (i.e.
data objects created outside of the process are not considered).
3. Each data object has always a state. In case an appearance of a data object
in the BP model is not associated with any state, this appearance will be
ignored.
4. The BP model can contain data objects connected to any kind of activity
(sub-processes are treated like task activities). Only XOR gateways can be
used.
Assumption 1 is made because control-flow soundness is out of the scope of this
paper. Assumptions 2 and 3 are reasonable and have also been made elsewhere
[2]. The last assumption is related to the reach of the current approach.
3.1 Step 1. From BPMN Model to Petri Net
We believe that providing a semantic mapping [7] between a BPMN model and
a target domain such as Petri nets, whose semantics has been formally defined,
is a good approach because it allows one to use the techniques specific to the
target semantic domain for analysing the source models. We chose Petri nets for
two reasons: (i) plenty of processing algorithms on Petri nets have already been
developed and can be useful for our purpose [6,8]; and (ii) the transformation
of the control flow of a BP model into an equivalent Petri net has already been
described in [6].
Definition 1. A Petri net is a 3-tuple PN =( T PN ,P,F ) ,where:
- T PN =
is the set of transitions of the Petri net, represented
graphically as rectangles.
- P =
{
t 1 ,t 2 , ..., t n }
{
p 1 ,p 2 , ..., p n }
is the set of places of the Petri net, represented graphi-
cally as circles.
- F
T PN ) ( T PN ×
( P
×
P ) is the set of arcs of the Petri net (flow relation),
represented as arrows.
A marking (state) or markup assigns a nonnegative integer to each place of a
Petri net. If it assigns to place p a nonnegative integer k ,wesaythat p is marked
with k tokens. Pictorially, we place k black dots (tokens) in place p .Amarkup
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