Mainstream workflow management systems are using procedural 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 allows 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 dynamic 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.
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Worklist instance execution user 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 DECLARE 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
particular, DECLARE illustrates how declarative approaches can indeed be used to
realize more flexible BPM solutions, while providing for various types of
support [
This demo presents the five main functionalities of DECLARE.
First, constraint templates are created on the system level as types of constraints. 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 (a) creating a constraint model
(b) executing a constraint model
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. Constraint 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 (a) adding a constraint dynamically (b) dynamic change report
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 DECLARE. 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
DECLARE is a fully functional constraint-based WFMS, and it allows for creating, 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.