The PHP Web Toolkit enables the rapid development of multi-layered web applications and is designed to be easy to use, extensible, reliable, reusable, scalable and secure. It integrates with ADOdb, FCKeditor, kses, Libmcrypt, Libmhash and Smarty.
Schema validation with simple dom php classes, that will check the xsd file before the xml based forms will accept any submit. The ajax wrapper should work with widgets to show any validation error to the form user.