CORD adopts a model-based design, which is to say all aspects of operating and managing CORD is mediated by a model-based control plane. XOS is a tool that CORD uses to implement this control plane. For an overview of XOS, see the XOS page on the CORD wiki.
XOS is a self-contained component of CORD, with its own Guide. Consult this Guide to learn how to use XOS to write models and synchronizers for CORD services. The Guide also describes how to install XOS as a stand-alone platform, which can be useful when developing models and synchronizers.