I am happy to announce that SDO 2.1.1 (JSR-235) has been approved by the JCP, and EclipseLink SDO is the reference implementation.
EclipseLink Download
http://www.eclipse.org/eclipselink/downloads/
Reference Implementation Download
http://www.eclipse.org/eclipselink/downloads/ri.php
SDO is a generic structure to represent data from many sources such as XML and relational databases, most commonly associated with SCA.
http://wiki.eclipse.org/EclipseLink/FAQ/WhatIsSDO
EclipseLink SDO was implemented as a thin layer on top of EclipseLink's object-to-XML layer (which is also the base for EclipseLink JAXB). EclipseLink SDO can be used alone, or as a means to expose POJOs as DataObjects so that components like EclipseLink JPA and JAXB can be used.
Accessing Relational Data as SDO DataObjects using JPA
http://wiki.eclipse.org/EclipseLink/Examples/SDO/JPA
Converting POJOs to/from SDO DataObjects using the POJO/SDO Bridge
http://wiki.eclipse.org/EclipseLink/Examples/SDO/JAXB
Thank you to all of the EclipseLink committers that contributed to the SDO component.
