Examples¶

The following are a list of examples for lib.mozilla.webthing.

Simple_Thing¶

In this example a simple Thing is created and will be able to control a LED. Properties, events and actions are exposed through the Mozilla Web of Things API specifications.

We used a Xinabox ESP32 which has an onboard LED.

See https://iot.mozilla.org/wot/#web-thing-rest-api for more informations.

How to run this example¶

Edit the Wi-Fi informations at the beginning of main.py; compile and uplink the project through Zerynth Studio and open the serial monitor.

Your board will print out it's local IP address and an URL you can use to begin with. E.g.: http://192.168.1.137/xinabox.

We'll be using curl command in a Linux terminal to easily test our API.

Fetch Thing informations¶

$ curl http://192.168.8.137/xinabox

{
  "name": "Xinabox ESP32",
  "description": "My really cool Xinabox ESP32",
  "properties": {
    "led": {
      "label": "LED",
      "type": "boolean",
      "readOnly": false,
      "description": "A LED which can be turned ON or OFF",
      "links": [
        {
          "href": "/xinabox/properties/led"
        }
      ]
    }
  },
  "actions": {
    "led": {
      "label": "LED",
      "description": "A LED which can be turned ON or OFF",
      "input": {
        "type": null
      }
    }
  },
  "events": {
    "led_change": {
      "description": "LED changed status"
    }
  },
  "links": [
    {
      "rel": "properties",
      "href": "/xinabox/properties"
    },
    {
      "rel": "actions",
      "href": "/xinabox/actions"
    },
    {
      "rel": "events",
      "href": "/xinabox/events"
    }
  ]
}

Fetch current LED status¶

$ curl http://192.168.8.137/xinabox/properties

{
  "led": true
}

Turn LED on/off¶

$ curl -XPUT -H 'Content-Type: application/json' -d '{ "led": false }' http://192.168.8.137/xinabox/properties/led

{ "led": false }


$ curl -XPUT -H 'Content-Type: application/json' -d '{ "led": true }' http://192.168.8.137/xinabox/properties/led

{ "led": true }

main.py

#############################################
# Simple_Thing
# Created at 2018-12-01 23:59:48.293498
#############################################

import streams
import json
import requests
from espressif.esp32net import esp32wifi as wifi_driver  # Esp32 Wifi driver
from wireless import wifi
import mcu
import threading

# Mozilla WebThing library
from mozilla.webthing import webthing


# Wifi SSID and password
SSID = "YourSSID"
PASSWORD = "YourPassword"


def setup_wifi():
    '''
    Init wifi driver and connect to the network using ssid and password
    provided in the `config` module.
    '''
    wifi_driver.auto_init()
    print("Establishing link to %s" % SSID)
    try:
        wifi.link(SSID, wifi.WIFI_WPA2, PASSWORD)
    except Exception as e:
        print("Error connecting to Wi-Fi")
        print(e)
        sleep(5000)
        mcu.reset()  # reboot device so it can retry
    print("Connected")


def get_timestamp_from_the_web():
    '''
    Fetch and return current timestamp from a web service.
    '''
    try:
        time_data = requests.get('http://now.zerynth.com').json()
        return time_data['now']['iso8601']
    except Exception as e:
        print("Error while obtaining current time")
        print(e)


streams.serial()  # init serial connection for print
setup_wifi()      # connect to Wi-Fi

# Init a Thing
xinabox_thing = webthing.Thing(
    "xinabox",
    "Xinabox ESP32",
    description="My really cool Xinabox ESP32",
    timestamp_fn=get_timestamp_from_the_web
)

# Register available EVENTS
xinabox_thing.register_event("led_change", "LED changed status")

# Register available PROPERTIES
# for this example a LED can change its status (on or off)
pinMode(LED0, OUTPUT_PUSHPULL)
digitalWrite(LED0, HIGH)
_led_status = True                  # we'll remember the LED status here


def get_led(payload=None):
    '''
    Return a boolean indicating if the led is currently on or not.
    '''
    res = _led_status
    return res


def set_led(status):
    '''
    Set the LED to a new status indicated in payload["led"].
    '''
    global _led_status
    digitalWrite(LED0, HIGH if status else LOW)
    _led_status = status
    xinabox_thing.signal_event('led_change', inp_data={"new_status": status})
    return status


xinabox_thing.add_property(
    "led",
    "LED",
    "boolean",
    get_led,         # This function is called on GET requests
    setter=set_led,  # This function is called on PUT requests
    description="A LED which can be turned ON or OFF"
)

# Register available ACTIONS
xinabox_thing.add_action(
    "led",
    "LED",
    callback=get_led,
    description="A LED which can be turned ON or OFF"
)

# Start the webserver exposing this Thing via HTTP requests
webthing.run_server(xinabox_thing)