Pattern-Based Modeling and Formalizing of Business Process Quality Constraints - Advanced Information Systems Engineering - page 525

Fig. 4. EPPSL quality constraint model

an "All" temporal relationship on the action "enter the pin number", since the word
"always" in QC 3 states that the temporal relationship "Until" must hold for all instances
of the action "enter the pin number".

Non-Deterministic Temporal Relationships: The non-deterministic temporal rela-
tionships are "PossiblyNext", "PossiblyAfter", "PossiblyUntil", and "PossiblyAll".
These relationships have the same semantics of "Next", "After", "Until", and "All" re-
spectively with one different aspect that they must not hold for all control flows of a
business process, but for at least one control flow. For example, we want to verify QC 4
on the business process model in Fig. 1.
QC 4 : "There exists a possibility after starting the process to check the application
data which is possibly followed by making an interview" .
The EPPSL model in Fig. 5 models QC 4 . It states that there exists at least one control
flow on which starting the process is followed by checking the application data which
is followed on at least one control flow by making an interview.

Fig. 5. EPPSL quality constraint model

4.3 Modeling Logical Relationships

A logical relationship may link actions, guards, and partial quality constraints. For ex-
ample, QC 2 consists of a logical relationship "Or" which combines two guards and
states that either the first guard "qualifications are sufficient" or the second one "quali-
fications are not sufficient" must follow the action "check the application data".
EPPSL provides the following set of modeling elements to express logical relationships,
which may link Actions, Guards, and ConstraintContainers:

- Join/ForkNode: is used to model the logical relationship "And". "Join/ForkNodes"
can be used to link Actions, Guards, and ConstraintContainers. We refer to Join/Fork
Nodes as control nodes.
- Decision/MergeNode: is used to model the logical relationship "Or". "Decision/
MergeNodes" can be used to link Actions, Guards, and ConstraintContainers. We
refer to Decision/MergeNodes as control nodes.
-Not: is used to model the "Not" logical operator. "Not" can be applied to Actions,
ConstraintContainers, and all EPPSL temporal relationship modeling elements.
- Connector: is used to model the "Imply" logical relationship. Connectors can link
between two ConstraintContainers, or between ConstraintContainers and control
nodes.