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.
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.
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.
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.)