SDO is a framework for data application development, which
includes an architecture and API. SDO does the following:

- Simplifies the J2EE data programming model
- Abstracts data in a service oriented architecture (SOA)
- Unifies data application development
- Supports and integrates XML
- Incorporates J2EE patterns and best practices

With SDO, you do not need to be familiar with a
technology-specific API in order to access and utilize data.
You need to know only one API, the SDO API, which lets you
work with data from multiple data sources, including
relational databases, entity EJB components, XML pages, Web
services, the Java Connector Architecture, JavaServer Pages
pages, and more.

This package contains only a Java API of SDO 2.1 spec.
EclipseLink is a implementation of this spec.