Regular ASP.Net gives you this trough server-side validation controls, which is up to you to embed in your forms. This generates client-side Javascript with vis

Regular ASP.Net gives you this trough server-side validation controls, which is up to you to embed in your forms. This generates client-side Javascript with visual feedback for the user, where you are to some extent in control how the results will look. If you tune up your ASP.Net to go include Enterprise Library you can use simple "proxy validation controls" which infers validation rules from attributes/annotations added to your base entity-classes. This again bleeds to the client-side allowing you to set validation rules once and only once. Even programmatic violation of these rules will result in errors. While rather enterprisey to work with, it is rather neat on a technical level. I'd be surprised if you can't do the same with Java. If you are however stuck with some ghetto PHP framework chances are yes, you will have to double or tripple your validation-logic because the language is simply too lacking to allow for complex runtime reflection based auto-generated sub-classes based on class metadata.