Anyone who has installed OBIEE in the past few years knows that the default web/application server that comes with the installation binaries is OC4J.  A lot of clients question having the application server and the BI Server on the same box, not only from an infrastructure standpoint but as well as a valid performance concern when implementing a distributed environment.  You have probably heard some performance “red-flag” statements such as “don’t use OC4J if you plan to have more than 200+ users hitting the server”, etc. just like I have.  And, that might be a valid statement, however, I have not personally benchmarked it with any performance testing software but it does make perfect sense once you uncover what OC4J really is.

OC4J is a slimmed down version of Oracle Application Server. For those that have done an OBIEE install, you are familiar with the one installation prompt where you can choose either the standard or advanced option.  If you choose advanced you are prompted to provide Oracle Application Server connection information. Otherwise, you are defaulted to OC4J.  And, this version of OC4J that you get with OBIEE is a pre-packaged “StandAlone” (or, unmanaged) version that only has a little more than the basic functionality that the full-blown Oracle Application Server (OAS) has.  Think of OC4J as OAS-lite.
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