Building web-based expert systems?

A client has asked us to build a web-based tool to help new users entering into their domain. The system would ask users questions to help build a profile on them and their interests. The profile could then be us开发者_StackOverflow中文版ed by real-life counselors in figuring out what the user needs to do next (ie get funding, find partners, do more research).

Ideally the user would be able to skip certain questions and continue on. At a later decision point the system could ask them if they would like to answer a previous question they skipped if that information is needed to go on.

My question is what is the best way to code a system like this? I have looked at Expert Systems and decision trees. The use case patterns seem to fit an Expert System but there don't seem to be any good web frameworks for either to build a tool like this.

Any recommendations for an open source solution?

One simple word: Databases

In that way you'll be able to save all questions, answers and unanswered questions which should be answered later. I'd recommend MySql