Probably your best bet is going to be either using PHP or Java servlets, which itself may or may not involve JSP. I've dealt with the Oracle stuff, and it is horribly clunky. We threw it away within a week of trying. Depending on your exact application, it's likely that the main portion of the load will be on your database and your network, so I would get your Oracle guys to concentrate on making Oracle work well. As long as you have programmers reasonably experienced in database programming, you should be okay no matter what exact solution you choose. The main advantage to PHP and servlets is going to be cost, relative ease of use, as compared to most of the proprietary solutions, flexibility, and the ease of finding help. Of course, that may all be moot if you need to support all of your 10,000 users on a single Sparc 5. Then it might behoove you to look at those proprietary solutions, as their advantage is usually that they're more efficient, at least in my experience.
The other big problem I see you having is in web page design. I've always found it to be much easier if you get a designer to work with you at the beginning to mock up what your web site should look like, with no real back-end. Just fake it. That allows your programmers to not have to worry about looks and usability too much when they should be busy programming; they can just plug data into preexisting templates.
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Bitt Faulk