Research On Model Transformation Between UML Behavior Models

Software modeling is very important for software development. With the rapidly expanding of software system scale and complexity, modeling language has become the key factor that influences software modeling. Unified Modeling Language(UML) was adopted as standard modeling language based on object-oriented technique by Object Management Group(OMG), November 1997. UML provides multiple graphics for system analysis and development. It is also applied to different phases of system developing. From requirement description to the testing and maintenance of the finished system, these modeling diagrams can integrate organically for analyzing and constructing a whole system. Now, UML has been widely accepted and used. Many companies have taken UML as a criterion for their development process and products.The study and application of UML model transformation are important to elaboration, optimization, reversion engineering, analysis and design patterns, software reconstruct, model consistency detecting of software development. Especially the appearance and development of MDA whose core technique is model transformation, celebrates the study and application of model transformation. To the software developers, model transformation can improve developing efficiency and model quality, convenient the model management and maintenance, guarantee the model consistence during system development. At the same time, the results of model transformation can help to judge accuracy and consistency of the models, improve the intelligibility of the system.Behavior models are very important models in UML, and will participate in every stage of object-oriented software development. They play an important role during the software development processes. We studied the problems of model transformation between the behavior models of UML. In the thesis, the concept and functions of model transformation, as well as its studying present situation, are introduced. The status of UML behavior models during object-oriented software development is specified. According to the problems of model transformation between the behavior models, we study the transformation between sequence diagrams and statechart for scenario description, the consistency detecting method of sequence diagrams and statechart ,and the transformation from sequence diagram to activity diagram .The thesis introduces our works from the following aspects:(1) Automatic transformation from sequence diagrams to statecharts based on Scenario We discuss the description method of scenario, as well as the definition and recognition of objection state, extend the state vector, proposed a series of rules for deriving state variable from use cases specification to form state vector. We also evaluate the sequence diagrams that describes the scenario by vector information. Based on these works, we propose an arithmetic that can produce statecharts from sequence diagrams. The arithmetic uses OCL attached semantic information.The algorithm is extendible so that to satisfy the extension of system requirement. It models only the objects that the developers are interested in or whose state changes are complex. At the same time, the execution efficiency is improved. In the data structure that transforms t, we introduce the scenario information. This data field provides facility for solving overgeneralized problem, producing implied scenario and extending use cases description. What's more, the scenario information provides also the gist for requirement track during the code test and test stage.(2)Study of detecting and constructing implied scenariosThere may be unexpected state transition paths among the statechart generated by work (1). Invalid unexpected state transition paths will cause misunderstanding to the actions of objects by developers. On the contrary, valid unexpected state transition path will help to extend the actions of objects. In order to elaborate the requirements, an algorithm to differentiate these paths and judge the validity of the paths is given. We described how to get new scenarios using unexpected state transition paths. A new concept of"object scenario message snippet"is put forward. Also the algorithm to generate these message snippet and the steps to construct the implied scenarios are proposed.The valid unexpected state transition paths and the scenario messages of generated statechart compose the implied scenario description. Generating implied scenario description can help to elaborate user requirements, as well as to extend requirement description. Especially during the system test stage, implied scenarios are important to test the generating of the use cases. (3)Study of the consistency of the sequence diagram and the statechartSequence diagrams describe the interactions of multiple objects according to time sequence, While statechart modeling all the actions during the whole lifecycle of the use cases. The events in statechart are accord with the messages in the sequence diagram. Many of aspects are overlapped in these two diagrams. We study and define the consistency of sequence diagram and statechart. Statechart are transformed to Finite state processes which is the text-describe form of LTS, and sequence diagrams are described as a trace of messages. We also analyze the two diagrams by LTSA so that the consistency is detected from two characters of existence and sequence. This is a simple method, need no additional information, and can be supported by suitable analysis tools. Detecting of consistency is important for detecting modeling mistakes during early development stage.(4) Study of transformation from sequence diagram to activity diagramThe concurrent operation semantics of the messages in sequence diagrams and the relationships between the actions of sending and receiving messages in UML 2.0 are described. We can get the sequential relationships of messages by mapping them to the messages. According to the sequential relationship of messages, we design the consistency mapping rules from sequence diagram to activity diagrams. The activity diagrams are called Message Semantics-based Concurrent Control Flow Graph(MSCCFG). Thus, the control flow information of sequence diagram can be got.Better concurrency of concurrent control flow can be got by this method, which is useful for consistency comparison to the control flows of activity diagrams expression use cases, and important to the test techniques based on sequence diagrams, also the compiling, comprehension and executing of the models.Further, we plan to perfect the works listed above, including the study of the whole system statechart of the generating objects, improving the arithmetic efficiency of constructing implied scenario, study of the new model transformation occurence by change of UML2.0 interaction diagrams and activity diagrams, the study of relationship between activity diagrams and other behavior models, and the implement of integrated model transformation tools.