Monitoring/inventory client-server app

[snorble]

I'm writing a tool for monitoring the workstations and servers in our
office. I plan to have a server and a client service that runs on each
workstation and reports back to the server (heartbeat, disk free
space, etc).

So far I am considering XMLRPC, or a client service that just
downloads a Python file and runs it.

With XMLRPC I don't know how to easily add features without having to
update every client. Also while playing with XMLRPC I learned that
when you run a registered function, it runs it on the server. I was
hoping it would run on the client, so that when I get the machine's
computer name (or disk space, etc) it will return the client's info.
It seems with XMLRPC I would have to hard code the functionality into
the client (i.e. client gets it's computer name, then calls the XMLRPC
function to pass it to the server)? I was hoping it would work more
like, "pass some code to the client to be run on the client, and
report it to the server". Almost XMLRPC in the reverse direction.

With the download-and-run approach, it seems trivially easy to add new
functionality to the clients. Just save the updated Python file to the
server, and clients download it and run it.

Are there any standard approaches to problems like this that can be
recommended? Thank you.