What is your experience regarding the scalability of Oracle Forms? What's the maximum number of application users you would use Oracle Forms for: 100, 1000, 10000, 50000?
I know that this question lacks many detail information for a well-founded answer. However, I am interested in the gut feeling of seasoned Forms developers.
Thanks.
Personal opinon: At this point, we tend to use Forms for complex UI apps with lots of validation and pretty intense usage.
If you can meet the business needs easily in a pure-web tool like ApEx (or any of hundreds of others), I wouldn't use forms.
So you'll probably need to assume that many of those Forms users are going to be keeping their connections pretty active.
And complex Forms use a lot of memory. We're running the app server on 34-bit Windows (not my choice) and running into memory limits with about 50 active connections.
Forms is pretty good on concurrency, so with reasonable coding you're not going to hit any major database limits. And app server processing and IO won't be your constraint. It's really just a matter of how many active users you're dealing with at one time, what their memory footprint is, and how big or how many app servers you're willing to deal with.
(Background: Forms Developer since version 2.3 (with a bit of 2.0), still using it for some projects and a lot of legacy)
You may find this Oracle white paper useful: Forms Capacity Planning Guide.
One thing to consider is that Forms is a "stateful" system, so connected users will actually be maintaining Oracle sessions. Contrast this with a "stateless" system like Oracle Application Express (APEX). I believe (but don't have evidence to prove it) that APEX will scale better than Forms (i.e. with less hardware).
I am currently involved in an APEX project that will have 2000 concurrent users. The original plan was to use Oracle Forms, but we didn't change because Forms couldn't scale to 2000 users (it could), there were other reasons for doing so.
In simple terms Oracle Forms scales. My evidence? Oracle E-business Suite uses it. If one of Oracle's premier products couldn't scale it would have been moved off this platform a long time ago.
I agree with Tony & Jim comments, in that Forms being more expensive to scale because of the use of persistent connections.