Oracle Application Server is highly scalable, as a J2EE application server. As demand grows for web applications in particular J2EE application server capacity grows vertically and horizontally.
Oracle Application Server can change its ability to vertically at more than one OC4J instance at a particular computer or a Java virtual machine in a particular instance of OC4J. An instance of Oracle Application Server can be configured to run multiple instances of OC4J or run. In this configuration, each instance of OC4J is to run its own JVM. However, several cases OC4J on the same computer is configured as a convenient way to OC4J scalability in many cases, a configuration file on the machine itself.
It is not uncommon for multiple applications to share the application server. By running multiple instances of OC4J uneven application runs in its own OC4J instance. This reduces the risk that may affect the implementation of the proposal and other programs. It also may account for the use of funds, as a necessary evil, surrounded by many companies.
The vertical scale is best done by running multiple processes in the JVM, OC4J Instance reached. You are using the computing power of multiple processors. If more than one JVM process works, objects and EJB session states between repeated HTTP JVM. In addition to increasing server capacity to handle incoming requests such a configuration, the server is also better prepared to recover from the failure of the JVM. In this type of errors, you can redirect requests to one of the other in the same instance of the JVM running OC4J.
Replicating HTTP session objects can be a daunting task. Thus we can say that replicating HTTP session objects can become a resource-intensive task. To cope with this condition replication, Oracle Application Server provides a mechanism that allows the degree of control. Each JVM is assigned to the island. Logical group is called as islands in the HTTP session replication JVM. If two or more JVMs, the name of the same island, which are themselves instances of Oracle Application Server on different nodes of the cluster, copy the HTTP session objects between them. This feature means that checking the state of the JVM with others.
However, there is no way to control the replication of EJB sophisticated. EJB state replication does not use the install Replication island. Stan EJB stateful replicated to all OC4J JVM instance or instances in a cluster of Oracle Application Server.