Graphical specification and formal verification of the Workflow Petri Nets properties in a business process context

State of the art organizations produce models of their business processes to ensure continuous improvement of their activities which help to achieve high revenue performance. They also use these models to build up quality and preserve knowledge. Business processes are determined according to the organization's function and they consist of a completely closed, timely and logical sequence of structured activities that contribute to fulfill a common purpose and mission. The business processes that are modeled within an organization are very often composed by components that contain various sub-processes. These interact with each other to accomplish a specific purpose as defined by the apex. The complexity level can be very high so that the BP designer becomes unable to manage the correctness of his entire design. Failure within the execution of the processes can be fatal and costly to repair. Therefore, providing a formal and automatic verification method is necessary to overcome the above drawbacks. We are interested in this study by using the formal methods for workflow process validation. Workflows have been established to manage the automatic execution of business processes. A workflow process is a set of activities that each contains executable tasks that consume and produce well defined data. We distinguish two main existing verification interests. In one hand, the workflow analysis axes that consist of verifying general properties like absence of deadlocks or livelocks. On the other hand, the use of verification tool to validate the dynamic properties of processes. The latest need a translation framework from the process workflow schema towards a format and content that are recognized by the verification software. The specification of the properties should also be expressed within a logic that is understood and supported by the software. We focus, in our case, on automatic and direct verification of a class of properties of the workflow processes. We are particularly interested in responses properties. These types of properties can be written as follows: Task “A” will always be followed by task “B”, or task “A” and task “B” will be executed in parallel and after task “A”. We use WFPN (Workflow Petri Net), introduced by Vander Aalst (1998), as a workflow formal model and a graphical user interface to specify the properties by using the same concepts as established in WFPN. We defined a formal semantic for these properties and we have implemented the verification algorithms inspired from existing formal methods. Our contribution relies on the integration of the formal verification techniques in the design phase. Constraints specifications on designed processes can be automatically and intuitively validated by the BP architect at this early stage.