ODE uses Git to manage its source code. Instructions on Git use can be found here.
ODE source can be checked out anonymously with this command:
$> git clone git://git.apache.org/ode.git
Once you have ODE checked out you can update the source by executing the following command from within the ode directory.
$> git pull
Once you've got the code you'll probably want to build it; for instructions see Building ODE.
If you make changes to ODE, and would like to contribute the to the project, you should create a patch and post it to the ODE JIRA issue tracker. To create a patch, simply execute one of the following commands:
$> git format-patch master --stdout > your-changes.patch :::text $> git diff > your-changes.patch
Everyone can access the ODE Git repository via HTTP, but ODE Committers must checkout the repository via HTTPS.
$> git clone https://git-wip-us.apache.org/repos/asf/ode.git
For further instructions, please see here