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IoT scenario

Device: Raspberry Pi

The Raspberry Pi is a series of small single-board computers. https://www.raspberrypi.org/

API

  1. gpiozero: A simple interface to everyday GPIO components used with Raspberry Pi. (https://gpiozero.readthedocs.io/en/stable/index.html)

  2. LED control example: https://gpiozero.readthedocs.io/en/stable/index.html

Device Usage and Workflow

  1. LED light on/off button: following example below. And set up circuit as below: https://www.raspberrypi.org/learning/python-quick-reaction-game/worksheet/
  2. implement call back function when button for LED light on/off
  3. when LED on/off triggered, a message will be sent to EC2 server (described below)
  4. server process request with LED light status
  5. web browser/apps query server for LED light status and display to end user

Backend Usage

  1. ngnix server up
  2. flask server up
  3. mongod up

Server - Flask & Nginx

Install

sudo pip install Flask

sudo pip install flask-pymongo

Run Server - Flask

cd /path/to/code
export FLASK_DEBUG=1
export FLASK_APP=server.py
flask run --host=0.0.0.0

Flask Server deployment

  1. spin up ec2 instance (Amazon Linux)
  2. get .pem key
  3. ssh -i /Users/xinr/Downloads/sapHackathon.pem [email protected]
  4. setup Mongo on centOS: https://docs.mongodb.com/manual/tutorial/install-mongodb-on-red-hat/

(@note: change .pem file to 600: chmod 600 /Users/xinr/Downloads/sapHackathon.pem)

(@note: user name is root, not centos. aws turotial is wrong at http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/AccessingInstancesLinux.html)

http://flask.pocoo.org/docs/0.12/deploying/#deployment

Nginx Server deployment

  1. sudo yum install nginx
  2. sudo /etc/init.d/nginx start
  3. nginx will redirect requests to localhost(127.0.0.1)

Ref: http://vladikk.com/2013/09/12/serving-flask-with-nginx-on-ubuntu/

Client

status request

http://localhost:5000/status?udid=d1

udpate request

http://localhost:5000/update?udid=d1&status=closed

@note: I didn't do param checking or exeception handling, here is just a super simple demo

MongoDB

PyMongo

sudo python -m pip install pymongo

https://api.mongodb.com/python/current/tutorial.html

MongoDB Server

sudo mkdir -p /Users/xinr/Downloads/mongodb/

mongod --dbpath /Users/xinr/Downloads/mongodb/

MongDB Query

use local
db.status.insert({'deviceId':'d1', 'status':'open'})
db.status.insert({'deviceId':'d2', 'status':'occupied'})

Schema

> db.status.find().pretty()
{
	"_id" : ObjectId("58e9681d2533a670f43efb17"),
	"deviceId" : "d1",
	"status" : "open"
}
{
	"_id" : ObjectId("58e9683c2533a670f43efb18"),
	"deviceId" : "d2",
	"status" : "occupied"
}

Front-End Hookup

Usage

  1. click 'Add' to add a green circle
  2. Drag circle to map
  3. click 'Refresh'

Color and Room Status

  • Green circle: room not occupied
  • Red circle: room is occupied

Endpoint

http://ec2-34-209-46-58.us-west-2.compute.amazonaws.com:5000/

return html file

  1. create a folder called templates
  2. and use built-in render_template
def hello(name=None):
    return render_template('hello.html', name='name')

Ref: http://flask.pocoo.org/docs/0.12/quickstart/#rendering-templates

for css and js files

  1. need to have a static folder setup (for css/js files)
  2. then: <link rel= "stylesheet" type= "text/css" href= "{{ url_for('static',filename='styles/mainpage.css') }}">

Ref: http://stackoverflow.com/questions/22259847/application-not-picking-up-css-file-flask-python