Poll an MTConnect agent's /current for execution state (Python)

"""Poll an MTConnect agent's /current and print execution state per device.

Usage:  python mtc_poller.py https://demo.mtconnect.org
"""

import sys
import time
import urllib.request
import xml.etree.ElementTree as ET

POLL_SECONDS = 2


def local_name(tag):
    """Strip the namespace off an ElementTree tag - '{uri}Execution' -> 'Execution'."""
    return tag.rsplit("}", 1)[-1]


def read_current(base_url):
    with urllib.request.urlopen(f"{base_url}/current", timeout=10) as resp:
        root = ET.fromstring(resp.read())

    devices = {}
    for device_stream in root.iter():
        if local_name(device_stream.tag) != "DeviceStream":
            continue
        name = device_stream.get("name")
        state = {}
        for elem in device_stream.iter():
            tag = local_name(elem.tag)
            if tag in ("Execution", "ControllerMode", "Availability", "PartCount"):
                state[tag] = elem.text
        devices[name] = state
    return devices


def main():
    base_url = sys.argv[1] if len(sys.argv) > 1 else "https://demo.mtconnect.org"
    print(f"Polling {base_url}/current every {POLL_SECONDS}s - Ctrl+C to stop.")
    try:
        while True:
            for name, state in read_current(base_url).items():
                avail = state.get("Availability", "?")
                exe = state.get("Execution", "?")
                mode = state.get("ControllerMode", "?")
                parts = state.get("PartCount", "?")
                print(f"{name:<10} avail={avail:<12} exec={exe:<10} "
                      f"mode={mode:<10} parts={parts}")
            print("-" * 60)
            time.sleep(POLL_SECONDS)
    except KeyboardInterrupt:
        pass


if __name__ == "__main__":
    main()