| JTang Application Server is a lightweight J2EE application server which developed by middleware technolog research center at Zhejiang university. It pass INTEL testing in 2006 and concluded that: "The platform is a pure Java development for enterprise application server which supports J2EE1.4 related standard such as Enterpirse Java Bean, Java Naming and Directory Interface, Java Message Service,Data Source, Java Server Page/Servlet."In order to provide high available EJB (Enterprise Java Bean) services, we need to develop EJB clustering which can achieve failover and load balance. The paper discusses several key technologies of EJB clustering, system implementation and system testing.At first, the paper introduces the background of middleware platform and related knowledge of clustering technology. Then a brief introduction of JTang application server software platform. To implement EJB clustering of JTang application server, paper proposed two design goals: load balance and failover, according to its own features. And design the architecture of JTang EJB clustering. Next, the majority of this paper is to solve several key technology of clustering. As EJB services related to RMI and JNDI technology, to achieve reliable EJB services, we must first implement reliable RMI service and JNDI service, which we called HA-RMI and HA-JNDI respectively. In HA-JNDI design, paper proposes a new storage structure with a new strategy to lookup and band resource. In HA-RMI design, paper proposes an intelligent agent, the agent can achieve load balance and failover. In addition, paper solves state synchronization of stateful session bean through interceptor of client. At the same time, paper designs a removable load balance services, users can apply their own strategy for load balancing.At last, paper discusses implementation of EJB clustering, including the detailed design of each module, a browser-based console. And system testing includes: load balancing and failover, performance testing and stress testing of session bean clustering both stateful and stateless. Test results showed that the system well support load balancing and failover and achieve high-reliability EJB services, at the same time the system performance also improved greatly. |
