A project is nothing without its source.
Apache OODT uses Apache Subversion to manage its Apache source code. You can read the book Version Control with Subversion online or pick up a copy at your favorite dead tree retailer, if you're unfamiliar with Subversion.
Anonymous Access
You can use your favorite Subversion tools to access OODT source repository. The repository URL is:
http://svn.apache.org/repos/asf/oodt
If you're behind a firewall or other access control mechanism that restricts HTTP access that Subversion needs, then using the secure HTTPS access method might work:
https://svn.apache.org/repos/asf/oodt
If all else fails, you might find better luck with an HTTP proxy; consult the Subversion and/or your tools documentation on configuring Subversion to use a proxy.
Repository Viewer
If you don't have access to Subversion client tools, or don't like the austere raw HTTP view that a Subversion repository provides, you can use the Apache ViewVC web application for a more friendly look at the OODT source repository.
Developer Access
If you've signed your Apache contributor's agreement and have your Apache user name, then by all means use Apache Subversion for Apache-authenticated access to the Apache OODT repository. Just don't sit there—do it!
The repository URL is:
https://svn.apache.org/repos/asf/oodt
(Astute readers will notice it's the same as the HTTPS URL above. Have a cookie.)