There is the JSF validation framework - the JSF Validators and the validation phase, in which they run. So far my intuition was, they are designed mostly for simple, local, independent checks - regex test, number validation, etc.
But then comes the question - how should the the complex validation scenarios be realized? By complex I mean: some long-running checks with possibly heavy backend calls (DB, WS) and side-effects involved. By how I mean: do they also fit into the validation framework?
What I have seen so far, is that people rather lean towards here into invoke application phase and custom error handling. And here comes the ugly part - custom error handling, so either coupling into JSF API (invalidating components, setting messages) or rendering everything by hand (independent of h:messages) - i.e. struggling hard only to mimic the already existing solution.
So the question is less about technical feasibility (defining validators) and more about best-practices.
Thx, Jarek