The SDO Java Source Code can be found in the Apache svn repository.

The code for the SDO API is housed in this repository at http://svn.apache.org/repos/asf/incubator/tuscany/java/spec/sdo-api/

The code for the current implementation can be found at  http://svn.apache.org/repos/asf/incubator/tuscany/java/sdo/

Source code for previous releases can be found at http://svn.apache.org/repos/asf/incubator/tuscany/tags/java/sdo/