GWT2SWF intend to provide software bridge between GWT and FLASH/FLEX. It means that using GWT2SWF you will be able to communicate between GWT and FLASH/FLEX. GWT2SWF provides SWFWidget and FlashPlayer version detection.
JavaFlashBridge provides integration of a Flash player within Java Panel container using JDic and JavaScript and Flash Integration Kit. The communication protocol is String-based, so it can be XML, serialized objects or anything else. It is event-driven.
Interfuse is a workflow framework that joins ("fuses") the services, rules and objects of a traditional application with user-defined workflow. Interfuse is lightweight and designed to be embedded in existing Java-based applications.