monitor.py it can monitor xenserver host and those VMs which is hosting on it,
but it depends on parse_rrd.py to parse XML-format data.
enjoy it
if have any problem, you can contact me
reference from http://community.citrix.com/display/xs/parse_rrd.py+(Python+Script+for+parsing+RRDs)
./monitor.py <host> <user> <password> <type>