Validate Me

[Jeff McDonald]

As part of the App kernel frameworks discussion Richard has discussed the
need for a validation frameworks. I'm breaking out the discussion on
validation because the topic is broad enough to benefit from a focused
discussion.

My random thoughts:
- All of Java can benefit from validation, and not just JavaFX. Where
should a validation frameworks fit into the Java ecosystem?

- Thinking about validation there are two categories that I can think of
(1)passive validation - this is the most obvious. A users types in a value
and submits it and validation is performed and either the input is bad or
it's good. (2) active validation - input is evaluated and validated during
the input process. As an example: Let's say you have a field that accepts
an email address. With passive validation the user could be informed that
they entered an invalid email address. In an active validation system the
field could restrict the user from entering invalid characters or stop
accepting input once a maximum size is reached.

- JavaFX can benefit from both passive and active forms of validation. The
important question becomes how to implement validation into the UI. Where
to place the hooks and response behavior in the UI code.

- What things work great in existing validation frameworks? What sucks?

- What libraries do you use? Why did you pick that library?

- What is missing from existing validation frameworks?

Cheers,
Jeff