In order to share what we've learned as widely as possible, and in appreciation of the common pool of research and software which makes projects like this feasible, the complete source code to SoNIA is available from the sonia site on SourceForge according to the terms of the GNU GPL license. SoNIA is written in Java, so you will a free java compiler if you want compile the code yourself.
By downloading the source code you agree to the terms of the GNU GPL license. The main idea is that you may use the code however you like, but any project which uses the code must also make its source code availible for free. This ensures that it will remain in the public domain for us all to use in the future.
A zip compressed archive of the most recent "stable" code is availble here[link].
SoNIA's code is stored using a concurrent versioning system so multiple people can work on it at once. It is possible to browse the archive and checkout (download) a read-only version of the most current changes from the SourceForge CVS page. If you are intrested in contributing to the development, please contact us.