Although I agree with the other contributers (chromatic and The Mad Hatter) that it is hard to design in advance to unknown requirements, it might be useful to keep a few design patterns in mind.

Specifically, you might have a look at the Filter pattern (GoF pattern), as well as the Dynamic Linkage pattern (Grand98).

References are Design Patterns and Patterns in Java.

Just my 2 cents, -gjb-

In reply to Re: Best way to 'add modules' to web app? by gjb
in thread Best way to 'add modules' to web app? by BUU

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