Sunday, July 13, 2008

How requests are forwarded to Oc4j

In case of an Application Server the most common types of requests are HTTP based and RMI-based requests.

For HTTP based request, within the application server environment, the Oracle HTTP Server (OHS) acts as a front-end listener and OC4J as the back-end J2EE application server.

For RMI-based requests —such as EJB and JMS—clients should send their requests directly to OC4J.

A browser accesses the OHS listener for all HTTP requests. The Oracle HTTP Server is an Apache server.

The request flow between Oracle HTTP Server and OC4J is as follows:
  1. incoming HTTP request is received by the Oracle HTTP Server listener.
  2. HTTP Server passes the request to an OC4J instance through the mod_oc4j module.

The connection between Oracle HTTP Server and OC4J uses the Apache JServe Protocol (AJP) on a port number negotiated during OC4J startup.

HTTP Application Listener request flow

AJP is faster than HTTP, through the use of binary formats and efficient processing of message headers.

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