To deploy your Web application in a cluster, you must have a mechanism to support load balancing (and optionally failover), configure a mechanism to replicate HTTP session data between servers in the cluster, and make sure your code supports distributed deployment.
Beginning in EAServer 6.0, the wlb Web application (Web-load balancer) provides load balancing for Web applications using HTTP redirects—see “Setting up and using the Web-load balancer”.
If a Web application is distributed and running in a cluster, EAServer replicates session data to all servers in the cluster, using persistent storage. EAServer stores session data in a persistent data store to support shared sessions and session failover.
No changes are required to your servlet and JSP implementation code to support distributed sessions, as long as:
You are managing session data using the servlet session APIs or some other mechanism where storage is not tied to the host server (such as an EJB session or entity bean).
You use a database (or an EJB entity bean that connects to a database) to store global data. You can use the Web application’s environment properties to store global read-only data.
Because session data is bound to a single user, you cannot use sessions to store global read-write data. Many applications use ServletContext properties to store global data, but the ServletContext is not global to a distributed application and cannot be used as a read-write shared-memory store.
