GWT Reflection give ability for GWT Developers to use reflection API on client side (browser side) of GWT Aplication.
GWT Reflection are composed of two component GWT Reflection Wrapper and GWT Reflection Description Generator.
GWT Reflection Wrapper – provides basic functionality for Java 1.4 reflection API, we use this component on client side.
GWT Reflection Description Generator – provides simple tool (you can use it as ANT task) which create helpers for GWT Reflection Wrapper. This description will by used in runtime of application to manipulate your application classes.