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Using REST API on Raspberry Pi

This article is about using AirVantage API for devices. It will focus on a device: the famous Raspberry Pi.

Operating System & network access

Starting this tutorial, I assume you have flashed a Rapsbian on your Raspberry Pi SD. To find it on the network, I used the Internet sharing capabilities of my Mac and nmap.

$ sudo nmap -sn 192.168.2.0/24
Starting Nmap 6.40 ( http://nmap.org ) at 2013-11-25 16:49 CET
Nmap scan report for 192.168.2.6
Host is up (0.00070s latency).
MAC Address: B8:27:EB:76:EA:56 (Raspberry Pi Foundation)
Nmap scan report for 192.168.2.1
Host is up.
Nmap done: 256 IP addresses (2 hosts up) scanned in 2.02 seconds

This command shows us an unique Raspberry Pi available at 192.168.2.6.

Connect to Raspberry Pi

• Connect to the Raspberry Pi we just found is simple.

$ ssh 192.168.2.6

• Now, we are ready to perform some work.

Define your data

• First of all, to be able to send and receive data, you have to describe your data to AirVantage. Here is the description, you just need to change the type value with a unique identifier for your application and the name and revision with the appropriate values for your use case.
• You can modify the <data> area. Once it matches your needs, save everything as model.app.

Don’t modify the asset id as it is used in the code source application or modify it accordingly

<?xml version="1.0" encoding="ISO-8859-1"?>
<app:application 
        xmlns:app="http://www.sierrawireless.com/airvantage/application/1.0" 
        type="com.test.airvantage.app" 
        name="AirVantage Greenhouse"
        revision="0.0.1">
 <capabilities>

    <communication>
      <protocol comm-id="SERIAL" type="REST" />
    </communication>

    <data>
      <encoding type="REST">
        <asset default-label="Greenhouse" id="machine">
          <variable default-label="Temperature" path="temperature" 
                                                type="double"/>
          <variable default-label="Luminosity" path="luminosity" 
                                               type="double"/>
          <setting default-label="Threshold" path="threshold" 
                                             type="int"/>
        </asset>
      </encoding>
    </data>
  </capabilities>
</app:application>

Install Requests

Before enjoying easy Requests, let’s install it.

# Installing Setuptools
wget https://bitbucket.org/pypa/setuptools/raw/bootstrap/ez_setup.py
sudo python3.2 ez_setup.py
# Installing pip
wget https://raw.github.com/pypa/pip/master/contrib/get-pip.py
sudo python3.2 get-pip.py
# Installing Requests
$ sudo pip install requests

Note: If you are wondering about Setuptools and pip, they are just prerequisites for installing Requests .

The app

Here is the app wich communicate with AirVantage’s RESTful APIs:

#!/usr/bin/env python3.2
from argparse import ArgumentParser
import json
import requests
from time import time

# Parse arguments
parser = ArgumentParser(description="Using RESTful AirVantage.")
parser.add_argument("identifier",
  help="Your identifier, defined on AirVantage, here a trimmed a MAC address.")
parser.add_argument("password", help="REST password.")
args = parser.parse_args()

#
# Sending data to AirVantage
#
timestamp = int( time() * 1000)
# +1000 and +2000 are here to avoid aving several data points at the same time
data = [
  {
    "machine.temperature": [
      { "value" : "23.2", "timestamp" : timestamp },
      { "value" : "24.5", "timestamp" : timestamp + 1000 },
      { "value" : "22.9", "timestamp" : timestamp + 2000 }
    ]
  },
  {
    "machine.threshold": [
      { "value" : "30", "timestamp" : timestamp }
    ]
  }
]

# Using Basic Authentication
url = "https://eu.airvantage.net/device/messages"
print("Sending to {}.".format(url))
response = requests.post( url,
  auth=(args.identifier, args.password),
  data=json.dumps(data),
  headers={'Content-type': 'application/json'}
)
print("Response: {}. Content: {}".format(response.status_code, response.text))

# Check if there are messages
message_url = "https://eu.airvantage.net/device/tasks"
print("Checking for messages at {}.".format(message_url))
response = requests.get( message_url,
  auth=(args.identifier, args.password),
  headers={'Content-type': 'application/json'}
)
print("Response: {}. Content: {}".format(response.status_code, response.text))
print("Done")

View your application running

The 2 first parameters are identifier and password: it’s the two fields you supplied when creating your system and when you have associated the application you had to keep in mind.

Look, it is alive:

$ ./rest.py "B827EB76EA56" your_rest_password
Sending to https://eu.airvantage.net/device/messages.
Response: 200. Content: []
Checking for messages at https://eu.airvantage.net/device/tasks.
Response: 200. Content: []
Done

Your data is now sent. You can check your data communication. Just go to Inventory > Systems, then pick your own and click Timeline. That is it.

If you want to try it but feeling a bit lazy, it is all available at GitHub.

Next Step

Continue the tutorial by using tools supplied by AirVantage to test your communication with your device.