The Design And Implementation Of DM_EJB Container Prototype System

EJB component technology, a new distributed computing technology, is specified by Sun. The component makes it possible to develop distributed and object-oriented applications for enterprises with Java. EJB container is a system that provides running environment and various basic services for these components. By this means, the application develop process has been simplified. The DM_EJB container system based on "the homemade DBMS: DM3" makes it easy and convenient for customers to establish the applications that are based on Java language.The global architecture of DM_EJB container system satisfies the general application requirements under the circumstances of the Three-tier application architecture. According to the functions to be realized, it includes the managements of customer service, the container management and the basic service.Based on the further study of EJB specification, the object-oriented ideas have been used for designing and implementing DM_EJB container system that accords with EJB specification. The EJB container system has been considered as an independent part as the different roles what the application server and EJB container play in the J2EE Platform. The component-access requests will be submitted and performed through CPI interface. EJB container needs to supply many kinds of services. For the purpose of improving the system flexibility and reusing the codes of the application, the EJB container and the services necessary are separated. The container accesses the necessary services through SPI interface. By offering these interfaces, DM_EJB container can not only makes use of the current services realized but also supports new kinds services occurs in the future. Furthermore, it can supply instant service support to web application services that need the services provided by EJB container.In the process of designing and Implementing of CPI and SPI interface, the following key techniques have been adopted. For instance, the proxy implementation of the remote interface and the EJB home interface of the container, the management of the lifecycle of the component objects and the pooling management of the component objects. Besides, the security service, transaction service and the database connection management service that have been achieved by the DM_EJB container system.