Oracle Containers for J2EE (OC4J) is a complete J2EE (Java 2 Platform Enterprise Edition) server written entirely in Java which executes on the standard Java Development Kit (JDK). It provides a complete J2EE environment that contains, among other things, a Java Servlet engine.
By default Forms uses the OC4J (J2EE) servlet engine.
In a simple scenario, an HTTP request is received by the Oracle HTTP Listener which passes it off to the Forms Listener Servlet running inside the OC4J process. This Forms Listener Servlet establishes a Forms Server Runtime process and is responsible for on-going communication between the client browser and the runtime engine.
As more users request Forms sessions, the requests are received by the HTTP
Listener Servlet which again passes them off to the Forms Listener Servlet which
will establish more runtime processes. The Forms Listener Servlet is a multi-threaded
process that can handle many Forms Runtime sessions simultaneously. There is,
of course, a limit to the number of concurrent users this servlet can support,
however,the architecture presents a number of opportunities for tuning and configuration
to achieve better performance.