Get raw performance data for an object.
Issue a GET request such as /api/beta/perfdata/fetch/?host=monitor&service=System%20load&ds=load1&start=-3600%20seconds.
Issue a GET request such as /api/beta/perfdata/fetch/?host=monitor&service=System%20load and the API will list datasources available for that resource.
You should urlencode all parameters (such as host and service) once.