GWT-VL stands for "Google Web Toolkit - Validation Library"!.
It is here to fill the gap of missing validation functionality from GWT. Its aim is to provide a library of prebuilt validation functionality as well as a framework that helps you to implement your own custom validation appearance and logic.
It takes care for you of the functionality common for all validation purposes, like connecting server side validation with the displaying of that information on the client side. Thus the only thing you need to think of is how you want your error indicators displayed visually and what you actually want to validate. All the ground work is already provided by this framework. Additionally to get you started fast, there are prebuilt ways of showing validation errors and validation logic.
For a quick overview about what you will get "out-of-the-box" visit the Showcase. Everything you can see there is already provided for by GWT-VL:
- The red border on the input fields
- The display of the description message of what to input into a specific field
- The display of a summary of all the failed validations
- I18n support
- The resetting of the failed validations indicators
- The cycling to the first input field that failed validations
- The different prebuilt validators like: StringLength, Integer, Range, RegularExpression, MultiEquals, etc.
And there is even more coming prebuild!
One further thing to mention is the i18n support. It is easy to write multilingual validation messages and the library even provides support for right to left languages like persian. The built-in validators are already localized for three languages: English, German and Persian (and its easy to extend them to further languages).
So in summary:
The GWT Validation Library takes care of two different aspects of input validation. These two aspects are
- the usability aspect
- and the security aspect
of input validation. As the security aspect is the only aspect that really matters, its a well-known fact (at least it should be) that you cannot ignore the usability aspect of validation.
Time saving validation development
As these two aspects of validation are a "must have" we can't ignore them during development of an application. But not be able to ignore some kind of functionality does not necessarily mean that it needs to be time consuming to implement it. So the GWT Validation Library was made to aid you in not needing to reinvent the wheel again and again. It also tries to give you great flexibility and richness for the usability aspect of validation while trying to assist you with a modular, reusable design that makes it easy and fast to implement the validation needs you have.
For a more specific introduction into the motivation for creating the GWT Validation Library you can check out the following blog article: mayduTechblog on GWT Validation Library.