Granite Data Services aims to be a free, open source (LGPL’d), alternative to Adobe® Flex™ 2 Data Services for J2EE application servers. Note that alternative does not mean replacement: it rather means that Granite DS supports AMF3 serialization/deserialization via RemoteObject.
GDS implements service factories required for:
EJB3 (Session and Entity Beans),
Simple Java classes (aka POJO) interactions.
GDS is designed to be lightweight, robust, fast and highly configurable. While GDS is still in early development stage, you should be already able to use the current 0.2 version in non critical production environment.