Design And Implementation Of EJB Container Of Webframe Application Server

In the Internet-based web computation, the traditional middleware technologies are challenged by the problems of high concurrency, distributed transaction, and integration of middleware and legacy systems. Web application server is put forward to solve those problems. A web application server is a distributed system that provides runtime-integrated services such as naming service, security service, transaction management, load balancing, fault tolerance etc, for transactional web application. Developers can concentrate on their own business logic rather than be involved in those issues. The research of this thesis focuses on the key technologies in developing EJB container, the kernel of an application server.Firstly, this thesis provides solutions for the issues of service framework of EJB container, multi-type client invocation, lifecycle management and persistence management for EJB. An extensible service framework of EJB container is presented, which allows services to be added transparently into the EJB container. Then, invocation using dynamic proxy is implemented for RMI/JRMP clients and invocation for RMI/IIOP is implemented in a way that the client can download IIOP stubs, which are automatically generated by the application server, from the stub server. Concerning the life circle management, caching and pooling technologies are used to provide efficient management. When it comes to persistence management, file-based persistence manager and JDBC-based persistence manager are both implemented.Secondly, load balancing and fault tolerance services, with which web application server cluster achieves its high reliability and scalability, are implemented in this thesis. The key requirements of adaptive load balancing services for web application servers are addressed, and the key design challenges including hot plug-in, customizable load balancing strategy, adaptive control, state migration and fault tolerance etc. are described. Then, based on the Proxy Fault ToleranceModel, a transparent fault tolerance service is put forward for all kinds of EJB. Concerning the state replication issue, three kinds of strategies-file-based replication, in-memory replication and database-based replication, are implemented.Lastly, in order to improve the overall performance of the application server, a task-queue-based and multithread-manageable RMI framework is presented in this thesis. The RMI logic is separated from the application logic. The result is that thread overload problem in Java RMI is solved and the timed request can be produced.The EJB container of Webframe, a J2EE compatible application server, has been developed based on this thesis. And Webframe has been used in the field of electronic government affair, electronic business and ERP systems.