Research And Implementation Of Object Modeling Tool Of Service-Oriented Platform Based On MDA

With the development of computer hardware and the popularization of computer applications, an increasing number of people pay attention to the other part of computer, software. We need to create the systems which are more complicated and more powerful to meet the requirements of computer applications. Such systems are often in large-scale and have many modules which can not be completed by a person or several people in a short period of time. It needs a number of teams to cooperate with each other to complete such systems. It is difficult to control the process of software development. The traditional software development way is unable to handle this problem. Software engineers are aware of the importance of model design. When we develop the large-scale systems, the time we spend on modeling is even longer than on coding. The model can help us implement the large-scale system easily. Coding is much easier when we have a well-designed model. However, the traditional development way describes the model in charts and text and stores them in documentations. Those documentations are hard to modify. As the developing process goes on, documentations are always abandoned or neglected and become just a pile of waste paper. Model Driven Architecture (MDA) has completely changed the situation we mentioned above.Model Driven Architecture (MDA) is a software development framework proposed by Object Management Group (OMG). MDA divides business requirements from implementation techniques. A series of models which are in different abstraction hierarchies are the main products of the developing process. These models are divided into two hierarchies: Platform Independent Model (PIM) and Platform Specific Model (PSM). The core idea of MDA contains two steps. The first step is to construct PIM. PIM is a high abstraction-layer model; it describes the behavior requirements of the system which are not related to any implementation techniques or platform information. The second step is to construct PSM by adding specific implementation technique into PIM according to the developing platform. The model transformation mapping mechanism controls the transformation from PIM to PSM. MDA advances the abstract hierarchy. When developing the abstract model, Software developer can ignore the specific implementation technique. MDA makes the software extensible and increases the development efficiency.With the popularization of management information system (MIS), more and more enterprises desire the information-based management. Enterprises and software developers have encountered many problems such as how to interconnect the multiple systems of the enterprise with low-cost, high flexibility and high scalability, how to fulfill data sharing and business collaboration between business partners, how to effectively manage and monitor internet communications which are in growing number.The developing of MDA service-oriented integrated platform, the major project of"Jilin Province Technology Development Plan", is to solve those problems above. This platform is a MDA-based, service-oriented and business process-oriented distribute software development platform. Using this platform, developers can customize and develop the workflow applications which process business requirements. Business flows can also be packaged as services and deployed on the service integrated platform. Service provider can publish their own services for others to visit by using this platform. At the mean time, service requestors can find the services they need and integrate them into their applications.The Object modeling tool is the core module of MDA service-oriented platform. It provides model service for the platform. It is designed according to Meta object Facility (MOF). It contains four layers: M3 meta-metamodel layer, M2 metamodels layer, M1 models layer and M0 information layer. In implementation point, the tool is divided into 3 layers: Storage layer, logic layer and presentation layer. The storage layer is the persistence layer of the system data. The logic layer is the interface which connects the storage layer and the presentation layer. The presentation layer is the User Interface of object modeling tool.The meta-modeling module is located in the storage layer. The main function of this module is to construct meta-models based on the models which are constructed by the model control module. Specifically, the functions of meta-modeling module are divided into two parts: One is to expand the relationships in object-oriented concept, which means to redefine some new relationships. These relationships not only consist of relationships between two objects (classes) but also attributes and objects, and two attributes. The other one is to expand the data types, which means to redefine a few of new data types.The EJB module is located in the logic layer. It manages the interaction between the storage layer and the presentation layer. It is used to control the program flow. It deals with behaviors of users in the presentation layer and changes the behaviors into atomic operations of database in the storage layer. Finally, it responds to the presentation layer.The implementation of model control module consists of two parts; one is database tables located in the storage layer, the other one is atomic operations defined by the EJB module. This part is located in the logic layer. Therefore, the model control module is across two layers of the object modeling tool. The model control module is the core module of object modeling tool. Whether the meta-modeling module or the transformations from abstract models to domain models, they both need the model control module. The main function of model control codule is to define and manage the work in each phase of the object modeling tool.The model management module is located in the presentation layer. It is used to transform abstract models to domain models. Specifically, when meta-models have been constructed, modeler uses model management module to construct and maintain domain models according to the domain (business) requirements. The model management module consists of three parts: class management, relationship management and attribute management.The original ideas of the object modeling tool of service-oriented platform based on MDA are listed as follows:The design of object modeling tool is based on MOF which is the core technique of MDA. Object modeling tool divides the traditional modeling process into two phases: meta-modeling and modeling. It can meet the modeling requirements of complex and large-scale system of different industries. When requirements have been changed or system has to be updated, we can rapidly adjust the models to meet the new requirements using the object modeling tool.In the meta-modeling phase, when original modeling elements (relationship, data type, attribute) can not meet system requirements, we can expand modeling elements by ourselves to meet the system requirements. At the mean time, it is easy to expand elements. Only two steps need to be taken: Firstly, create new modeling elements; secondly, design atomic operations for new elements. The object modeling tool has expanded the relationships in object-oriented concept. It has created attribute-attribute relationship and object-attribute relationship and has implemented the relationships in the EJB module.