This figure illustrates an Oracle
Application Server configuration using port tunneling. The iaspt daemon,
a stand alone component, acts as a communication concentrator for connections
between Oracle HTTP Server, which is guarded by firewalls on both sides,
and OC4J.
Oracle HTTP Server does not connect
directly to OC4J. Instead, it connects to the iaspt daemon which then forwards
communication on to OC4J. Each iaspt daemon routes requests to multiple
OC4J instances. By doing this concentration of connections, only one port
is opened per port tunneling process on the internal firewall, instead
of one port per OC4J instance.