Oracle Application Server is highly scalable as a J2EE application server. As demand for a particular J2EE web application grows, so too can the application server’s capacity grow, both vertically and horizontally. The following subsections describe the various types of scaling supported by the product.
Vertical Scaling with OC4J
Oracle Application Server can scale its capacity vertically by running more than one instance of OC4J on a given host, or by running more than one Java Virtual Machine in a given instance of OC4J.
Multiple OC4J instances per host
An Oracle Application Server instance can be configured to run one or more instances of OC4J. In such a configuration, each OC4J instance runs with its own JVM. However, running multiple instances of OC4J on the same host is more of a configuration convenience than it is a means of scalability because multiple OC4J instances on a single machine share the same configuration files.
It isn’t uncommon for several applications to share an application server. By running multiple OC4J instances, each heterogeneous application can run in its own OC4J instance. This reduces the risk that the deployment of an application may affect other applications (or appear that it has). It also makes it possible to do resource consumption accounting by application, which is a necessary evil in many business environments.
Multiple JVM processes per OC4J instance
Vertical scaling is better achieved by running more than one JVM process ...