weatherflow_listener.py

import socket
import select
import time
import struct
import pprint
import json
import datetime

# create broadcast listener socket
def create_broadcast_listener_socket(broadcast_ip, broadcast_port):

    b_sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP)
    b_sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)

    b_sock.bind(('', broadcast_port))

    mreq = struct.pack("4sl", socket.inet_aton(broadcast_ip), socket.INADDR_ANY)
    b_sock.setsockopt(socket.IPPROTO_IP, socket.IP_ADD_MEMBERSHIP, mreq)

    return b_sock


# map for the 'obs_st' type observations
OBS_ST_MAP = [
    ('Time Epoch', 'Seconds'),
    ('Wind Lull (minimum 3 second sample)', 'm/s'),
    ('Wind Avg (average over report interval)', 'm/s'),
    ('Wind Gust (maximum 3 second sample)', 'm/s'),
    ('Wind Direction', 'Degrees'),
    ('Wind Sample Interval', 'seconds'),
    ('Station Pressure', 'MB'),
    ('Air Temperature', 'C'),
    ('Relative Humidity', '%'),
    ('Illuminance', 'Lux'),
    ('UV', 'Index'),
    ('Solar Radiation', 'W/m^2'),
    ('Precip Accumulated', 'mm'),
    ('Precipitation Type', '0 = none, 1 = rain, 2 = hail'),
    ('Lightning Strike Avg Distance', 'km'),
    ('Lightning Strike Count', ''),
    ('Battery', 'Volts'),
    ('Report Interval', 'Minutes')
]

# map for the 'rapid_wind' type observations
RAPID_WIND_MAP = [
    ('Time Epoch', 'Seconds'),
    ('Wind Speed', 'm/s'),
    ('Wind Direction', 'Degrees')
]

# map for the 'evt_strike' type observations
EVT_STRIKE_MAP = [
    ('Time Epoch', 'Seconds'),
    ('Distance', 'km'),
    ('Energy', '')
]

# ip/port to listen to
BROADCAST_IP = '239.255.255.250'
BROADCAST_PORT = 50222

# create the listener socket
sock_list = [create_broadcast_listener_socket(BROADCAST_IP, BROADCAST_PORT)]

while True:
    # small sleep otherwise this will loop too fast between messages and eat a lot of CPU
    time.sleep(0.01)

    # wait until there is a message to read
    readable, writable, exceptional = select.select(sock_list, [], sock_list, 0)

    # for each socket with a message
    for s in readable:
        data, addr = s.recvfrom(4096)

        # convert data to json
        data_json = json.loads(data)

        if data_json['type'] == 'obs_st':
            # takes the map list and the list of observations and creates a dictionary with the first value in
            #  the map as the key and the first value in the list of observations as the value, second value
            #  to second value, etc
            observations = dict(zip(OBS_ST_MAP, data_json['obs'][0]))
            observations['Datetime'] = datetime.datetime.fromtimestamp(observations[('Time Epoch', 'Seconds')])
            pprint.pprint(observations)

        elif data_json['type'] == 'rapid_wind':
            observations = dict(zip(RAPID_WIND_MAP, data_json['ob']))
            observations['Datetime'] = datetime.datetime.fromtimestamp(observations[('Time Epoch', 'Seconds')])
            pprint.pprint(observations)

        elif data_json['type'] == 'evt_strike':
            observations = dict(zip(EVT_STRIKE_MAP, data_json['evt']))
            observations['Datetime'] = datetime.datetime.fromtimestamp(observations[('Time Epoch', 'Seconds')])
            pprint.pprint(observations)

        elif data_json['type'] == 'evt_precip':
            # no other information other than the timestamp is included so just print a simple message
            print('It started raining at {}!'.format(datetime.datetime.fromtimestamp(data_json['evt'][0])))

        else:
            print(data_json)