Research Of Use Case Modeling Based On Petri Net

Requirement Engineering (RE) is very important and basic in the whole Software Life Cycle. With the increase of software's scale and complexity, RE becomes more important because it directly connects with the success or failure of the system. Use Case, as a strong Modeling tool, is mainly used for recording the System requirement. Following the definition of Use Case, there are many developments in the Software. The method driven by Use Case is that Use Case is the basis and start point of the software process. The Use Case is used throughout the software process, including getting requirement, system design, software test, software process.But in UML, there are no any unique rules for the description of Use Case. The different users use different methods. This makes some disagreement and ambiguity. The Use Case description formalization is good method for this. The known methods are too complex for the user of the early step. These methods have not enough power for the description of parallel and concurrency. The graphic description is a good method for this. There are some study about this based on activity graph, which inherits the limitation of UML that has no exact grammatical meaning. And there are few methods for the analysis for the System Model by UML.Taking account of the above two problems, the author gives the description formalization of Use Case by the introduction of the definition of event sequence. A mapping algorithm is constructed from the Use Case to Petri Nets model, and a Use Case modeling method based Petri Net is got. This method is not only improvement for the description formalization, but also good for the graphic description of Use Case. Hence the model can be test by the tools of Petri Net, and the quality of the software is improved.