Coverage for tutorials/ngsi_v2/e1_virtual_weatherstation/e1_virtual_weatherstation.py: 0%

1""" 

2# # Exercise 1: Virtual Weather-Station 

3 

4# Create a virtual IoT device that simulates the ambient temperature and 

5# publishes it via MQTT. The simulation function is already predefined. 

6# This exercise gives a simple introduction to the communication via MQTT. 

7 

8# The input sections are marked with 'ToDo' 

9 

10# #### Steps to complete: 

11# 1. Set up the missing parameters in the parameter section 

12# 2. Create an MQTT client using the paho-mqtt package with mqtt.Client() 

13# 3. Define a callback function that will be executed when the client 

14# receives message on a subscribed topic. It should decode your message 

15# and store the information for later in our history 

16# `history_weather_station` 

17# 4. Subscribe to the topic that the device will publish to 

18# 5. Create a function that publishes the simulated temperature `t_amb` and 

19# the corresponding simulation time `t_sim `via MQTT as a JSON 

20# 6. Run the simulation and plot 

21""" 

22 

23# ## Import packages 

24import json 

25import time 

26from urllib.parse import urlparse 

27from uuid import uuid4 

28import matplotlib.pyplot as plt 

29import paho.mqtt.client as mqtt 

30 

31# import simulation model 

32from tutorials.ngsi_v2.simulation_model import SimulationModel 

33 

34# ## Parameters 

35# ToDo: Enter your mqtt broker url and port, e.g. mqtt://test.mosquitto.org:1883. 

36MQTT_BROKER_URL = "mqtt://test.mosquitto.org:1883" 

37# ToDo: If required, enter your username and password. 

38MQTT_USER = "" 

39MQTT_PW = "" 

40 

41# ToDo: Create a unique topic that your weather station will publish on, 

42# e.g. by using a uuid. 

43UNIQUE_ID = str(uuid4()) 

44TOPIC_WEATHER_STATION = f"fiware_workshop/{UNIQUE_ID}/weather_station" 

45 

46# set parameters for the temperature simulation 

47TEMPERATURE_MAX = 10 # maximal ambient temperature 

48TEMPERATURE_MIN = -5 # minimal ambient temperature 

49 

50T_SIM_START = 0 # simulation start time in seconds 

51T_SIM_END = 24 * 60 * 60 # simulation end time in seconds 

52COM_STEP = 60 * 60 # 60 min communication step in seconds 

53 

54# ## Main script 

55if __name__ == "__main__": 

56 # instantiate simulation model 

57 sim_model = SimulationModel( 

58 t_start=T_SIM_START, 

59 t_end=T_SIM_END, 

60 temp_max=TEMPERATURE_MAX, 

61 temp_min=TEMPERATURE_MIN, 

62 ) 

63 

64 # define a list for storing historical data 

65 history_weather_station = [] 

66 

67 # ToDo: Create an MQTTv5 client with paho-mqtt. 

68 mqttc = ... 

69 # set user data if required 

70 mqttc.username_pw_set(username=MQTT_USER, password=MQTT_PW) 

71 

72 # ToDo: Define a callback function that will be executed when the client 

73 # receives message on a subscribed topic. It should decode your message 

74 # and store the information for later in our history. 

75 # Note: Do not change the function's signature! 

76 def on_message(client, userdata, msg): 

77 """ 

78 Callback function for incoming messages 

79 """ 

80 # decode the payload 

81 payload = msg.payload.decode("utf-8") 

82 # ToDo: Parse the payload using the `json` package and write it to 

83 # the history. 

84 ... 

85 

86 pass 

87 

88 # add your callback function to the client. You can either use a global 

89 # or a topic specific callback with `mqttc.message_callback_add()` 

90 mqttc.on_message = on_message 

91 

92 # ToDo: Connect to the mqtt broker and subscribe to your topic. 

93 mqtt_url = urlparse(MQTT_BROKER_URL) 

94 ... 

95 

96 # ToDo: Print and subscribe to the weather station topic. 

97 print(f"WeatherStation topic:\n {TOPIC_WEATHER_STATION}") 

98 mqttc.subscribe(topic=TOPIC_WEATHER_STATION) 

99 

100 # create a non-blocking thread for mqtt communication 

101 mqttc.loop_start() 

102 

103 # ToDo: Create a loop that publishes every 0.2 seconds a message to the broker 

104 # that holds the simulation time "t_sim" and the corresponding temperature 

105 # "t_amb". 

106 for t_sim in range( 

107 sim_model.t_start, int(sim_model.t_end + COM_STEP), int(COM_STEP) 

108 ): 

109 # ToDo: Publish the simulated ambient temperature. 

110 ... 

111 

112 # simulation step for next loop 

113 sim_model.do_step(int(t_sim + COM_STEP)) 

114 time.sleep(0.2) 

115 

116 # close the mqtt listening thread 

117 mqttc.loop_stop() 

118 # disconnect the mqtt device 

119 mqttc.disconnect() 

120 

121 # plot results 

122 fig, ax = plt.subplots() 

123 t_simulation = [item["t_sim"] / 3600 for item in history_weather_station] 

124 temperature = [item["t_amb"] for item in history_weather_station] 

125 ax.plot(t_simulation, temperature) 

126 ax.set_xlabel("time in h") 

127 ax.set_ylabel("ambient temperature in °C") 

128 plt.show()