Apache ActiveMQ is a popular and powerful message broker and enterprise integration patterns provider. Apache ActiveMQ is fast, supports many cross language clients and protocols, comes with easy-to-use enterprise integration patterns and many advanced features, while fully supporting JMS 1.1 and J2EE 1.4.
RestyGWT is a GWT generator for REST services and JSON encoded data transfer objects. RestyGWT Rest Services allow you to define an asynchronous service API which is then implemented via GWT deferred binding by RestyGWT. It features generation of asynchronous RESTful JSON based service proxies, encoding and decoding of Java objects to JSON, and an easy-to-use REST API.