The first goal of Plexxi/Congress project was to create a driver for the OpenStack policy engine, Congress, that integrated data from PlexxiCore, a system that contains a database with wealth of network information. In congress, 'Drivers' are software that live within the congress server and while the server is running the drivers constantly pull data from their respective data sources and put this into tables for congress to use.
Having a Plexxi Driver allows congress to create and populate tables with data gained from PlexxiCore inside of Congress. This data can then be used within Congress to create network policies. Also, this driver also demonstrates one use of data from PlexxiCore inside a policy. The driver can be configured to have Congress monitor and react to the current state of the network with a policy to check for duplicate virtual machine names on separate hypervisors. This feature is demonstrated in the video on this page.
Once getting started with Congress drivers we then used Plexxi's opensource vCenter integration project as a starting point to create a vCenter driver for Congress. This driver, functions similarly to PlexxiCore driver and connects congress with another rich source of network information.