The VersionOne Data mart is a data store that has been optimized for analytics and reporting.  Using the information provided in the Data mart, any RDBMS reporting tool can be configured to generate the reports currently available in VersionOne and extend these reports as desired by your organization.  All reports can be analyzed from the perspectives available in VersionOne, and new perspectives such as Goals or custom drop downs, that are configured in your VersionOne instance, are also available.  Finally, you can create new reports based on custom numeric fields configured in your VersionOne instance.

 

The VersionOne Integration Platform is an open-source toolkit for building applications that integrate with the VersionOne Application.  

An external application or integration can interact with the VersionOne server using one of the following methods

We also see that each layer builds on the previous layer.  The higher layers make development simpler and faster, but with that simplification comes a loss of power/expressiveness.   Most projects should only need the Object Model Library, but there is the ability to 'drop down' to using the APIClient directly for more advanced capabilities - and there's always the option to work directly against the API.