How to run a python script on the server, returning the results to the client

Here's the end result I'm trying for:

• the user clicks on a feature on an ArcGIS Server JS map


• a Python script is triggered on the server


• the Python script uses an attribute from the feature (eg its OID) to perform some calculations (using arcpy modules)


• the results are returned to the infoWindow as HTML, for display

I guess I'd need to be able to trigger a Python script (containing arcpy commands) on the server, passing parameters between the client and server.

Assuming this is possible, what is the best approach:

• via the ArcGIS Server geoprocessing framework


• directly via an AJAX call to the Python script (and is that even possible)?


• something else?