=Paper=
{{Paper
|id=Vol-489/paper-1
|storemode=property
|title=DECLARE Demo: A Constraint-based Workflow Management System
|pdfUrl=https://ceur-ws.org/Vol-489/paper1.pdf
|volume=Vol-489
|dblpUrl=https://dblp.org/rec/conf/bpm/PesicSA09
}}
==DECLARE Demo: A Constraint-based Workflow Management System==
https://ceur-ws.org/Vol-489/paper1.pdf
DECLARE Demo:
A Constraint-based Workflow Management
System
Maja Pesic, Helen M. Schonenberg, and Wil van der Aalst
Department of Mathematics and Computer Science,
Eindhoven University of Technology,
P.O. Box 513, NL-5600 MB, The Netherlands
m.pesic,m.h.schonenberg,w.m.p.v.d.aalst@tue.nl
Abstract. Mainstream workflow management systems are using proce-
dural languages ranging from BPMN and EPCs to BPEL and YAWL.
By demonstrating DECLARE, we will show that it is also possible to use
a fundamentally different approach based on constraints. DECLARE al-
lows for multiple constraint-based languages whose semantics are grounded
in Linear Temporal Logic (LTL). The DECLARE system provides a
broad range of functionalities ranging from design, enactment and dy-
namic change to verification, discovery and recommendation. This demo
presents the main functionalities of DECLARE and is intended for both
researchers and practitioners interested in innovative BPM solutions for
processes that require flexibility.
1 Introduction
DECLARE1 [1, 2] is a constraint-based WFMS. The core of the system consists
of three components, as shown in Figure 1. First, the Designer component is
used for creating constraint templates, defining organizational structures, cre-
ating and verifying constraint models. Second, instances of constraint models
are enacted and dynamically changed in the Framework tool. Finally, each user
1
http://declare.sf.net
Worklist
Designer
DECLARE
Framework instance execution
constraint templates user
...
...
organizational structure instance enactment
constraint models instance dynamic change
model verification Worklist
instance execution
user
constraint templates constraint models
Fig. 1. Architecture of DECLARE
II
uses his/her Worklist component to access active instances and execute their
tasks. DECLARE is a Java desktop application and is distributed under terms
of the GNU General Public License. There is also a tight coupling between DE-
CLARE and ProM2 allowing for innovative forms of analysis and support, e.g.,
recommending particular process paths based on historic information.
DECLARE is significant and innovative in the BPM field because it uses a
declarative constraint-based approach instead of the procedural one. In partic-
ular, DECLARE illustrates how declarative approaches can indeed be used to
realize more flexible BPM solutions, while providing for various types of sup-
port [1]. However, the constraint-based approach (and DECLARE) is suitable
for smaller business processes: using this approach for complex processes signif-
icantly reduces the efficiency and usability of the tool .
2 Main Functionalities
This demo presents the five main functionalities of DECLARE.
First, constraint templates are created on the system level as types of con-
straints. Figure 2 shows that a template is graphically represented as a special
line between tasks. The formal specification of the template is given as a Linear
Temporal Logic formula.
2
http://prom.win.tue.nl/research/wiki/
Fig. 2. Creating the response template
III
(b) executing a constraint model
(a) creating a constraint model
Fig. 3. Creating and executing constraint models
Second, constraint models are created by adding tasks and using constraint
templates to create constraints between tasks. Figure 3(a) shows a model with
tasks curse, pray, bless and become holy, and two constraints. Constraint response
specifies that every time one curses, one has to eventually pray afterwards. Con-
straint 1..* specifies that one has to pray at least once. Third, Figure 3(b) shows
how a model from Figure 3(a) is executed in the Worklist. The whole model is
shown to the user, tasks are executed by double-clicking, and states of constraints
are presented via special colors: red for satisfied, orange for temporarily violated
(not satisfied at the moment, but can become satisfied in the future) and red for
permanently violated (not satisfied at the moment, and cannot become satisfied
in the future).
(b) verification report
(a) a model with an error
Fig. 4. Verifying constraint models
IV
(a) adding a constraint dynamically (b) dynamic change report
Fig. 5. Dynamically changing instances of constraint models
Fourth, Figure 4(b) shows how our verification procedure detects an error
in the model model shown in Figure 4(a): task curse is dead. This is due to
constraints not co-existence between tasks curse and become holy, which specifies
that one cannot both curse and become holy, and 1..* on task become holy, which
specifies that one must become holy at lest once.
Finally, Figure 5(a) illustrates the support for dynamic changes in DE-
CLARE. Constraint precedence between tasks pray and become holy is added
to all current and future instance of the model. Because this constraint requires
that one must pray before one becomes holy, and task become holy has already
been executed before task pray in instance number 4, this change is applied to
all active instances except the instance number 4 (cf. Figure 5(b)).
3 Conclusions
DECLARE is a fully functional constraint-based WFMS, and it allows for cre-
ating, verifying, executing and dynamically changing constraint-based process
models. DECLARE proves that a declarative approach can be applied to WFM,
which makes WFMSs more flexible.
References
1. W.M.P. van der Aalst, M. Pesic, and H. Schonenberg. Declarative workflows: Bal-
ancing between flexibility and support. Computer Science - Research and Develop-
ment, 23(2):99–113, May 2009.
2. M. Pesic, M.H. Schonenberg, and W.M.P. van der Aalst. DECLARE: Full Support
for Loosely-Structured Processes. In Proceedings of the 11th IEEE International En-
terprise Distributed Object Computing Conference (EDOC), pages 287–298, Wash-
ington, DC, USA, 2007. IEEE Computer Society.