On your way in you may have missed that we have a policy on screen names here at JavaRanch. Basically, it must consist of a first name, a space, and a last name, and not be obviously fictitious. Since yours does not conform with it, please take a moment to change it, which you can do right here.
As to your question, can you describe a bit more of your architecture? A servlet can't call an applet in the general case (a servlet runs on the server, while an applet runs on the client). So unless this is a special case (like everything running on your local machine), it may be more complicated than setting the codebase attribute.