The Argo project is a simple, extensible, framework for controling a host running multiple Xen instances.
The monitoring system is setup in two halves:
A network server which accepts commands via a simple text-based protocol and takes action on a local Xen host.
Any number of clients written in any network-capable language to provide the GUI
So far several clients have been produced: A PHP4 client, a Perl GUI, and a console based client using netcat and dialog.
Development upon argo has ceased pending a redesign.