Wt (pronounced 'witty') is a C++ library and application server for developping and deploying web applications. The API is widget-centric, and inspired by existing C++ Graphical User Interface APIs. To the developer, it offers complete abstraction of any web-specific implementation details.
DWR, or Direct Web Remoting is a Java open source library which helps developers wanting to write web sites that include Ajax technology. It allows code in a web browser to use Java functions running on a web server as if those functions were within the browser. It consists of 2 main parts:
Echo2 is the next-generation of the Echo Web Framework, a platform for developing web-based applications that approach the capabilities of rich clients. The 2.0 version holds true to the core concepts of Echo while providing dramatic performance, capability, and user-experience enhancements made possible by its new Ajax-based rendering engine.