Internet-of-Things Web Server

Web server to:

Store data from IoT devices in format

The data has two kind of objects releated:
* Object key: has all the attributes to descript an object, only exists
              one object for each array of values
* Object value: has the reference of the description object, and all the 
              values in a given date time and the date time

Create data triggers to send alerts

Exposed methods

The web server expose REST methods to manage keys and values.

Key object managing

Methods to manage key objects [GET|POST|PUT|DELETE]. The URL is /key/ A key object is an object that can have a collection of values and can belong to an other key object in an hierarchy of key objects. A key object must have the following mandatory attributes:

id
name: default value string empty
description: default value string empty
unit:
- code: code of the measure unit of the key (ex: m, kg, l, cm, ...), default value string empty
- description: description of the measure unit (ex: meter, kilogram, liter, ...), default value string empty
parentKey: id of the parent key, if does not has a parent key the value is string empty

/key/ [GET|POST|PUT|DELETE]:

Ex: Get a key

  Request:
    [GET] /key/198O3JLKEDJE1312
   
  Response:
    200,
    { 
      id: "198O3JLKEDJE1312",
      name: "", 
      description: "",
      unit: { code: "", description: "" },
      parentkey: "" 
    }

Ex: Post a key

  Request:
    [POST] /key
    Data: { name: "", description: "", unit: { code: "", description: "" }, parentKey: ""}
     
  Response:
    200,
    {
      id: "198O3JLKEDJE1313",
      name: "", 
      description: "", 
      unit: { code: "", description: "" }
      parentkey: "" 
    }

Value object managing

Methods to manage value objects [GET|POST|PUT|DELETE] A value object must have the following mandatory attributes:

id
value
timestamp
key: id of the key

/key//value/ [GET|POST|PUT|DELETE]:

Ex: Gets all the values from a key

  Request:
    [GET] /key/198O3JLKEDJE1312/value
    
  Response:
    200,
    { 
      id: "198O3JLKEDJE1312",
      name: "", 
      description: "",
      unit: { code: "", description: "" },
      parentkey: ""
      values: 
        [
          {
             id: "198O3JLKEDJE1313",
             value: "123.567",
             timestamp: ""
          }
           ...
        ]
    }

Ex: Get a value from a key

  Request:
    [GET] /key/198O3JLKEDJE1312/value/20934rjñlkqwdjfwq4
    
  Response:
    200,
    { 
      id: "198O3JLKEDJE1312",
      name: "", 
      description: "",
      unit: { code: "", description: "" },
      parentkey: ""
      value: 
        {
           id: "198O3JLKEDJE1313",
           value: "123.567",
           timestamp: "" 
        }
    }

Ex: Posts a new value

  Request:
    [POST] /key/198O3JLKEDJE1312/value 
    Data: { value: 123.567 }
    
  Response:
    If the node id exists and the value field exists:
    200, 
    {
      id: "198O3JLKEDJE1312",
      value: "123.567",
      timestamp: "",
      key: "198O3JLKEDJE1312"
    }

Internet-of-Things Clients

Simple client to water the plants

This client has to do the following tasks:

Control that the water depot has enough water, if not stop irrigate plants and send message
Water the plants according to some time table

The client needs to be configured before start with the following values:

Wifi and password
Internet-of-Things web server address, user and password
Email server to send alerts
Angle of the ultrasonic sensor from vertical

This client is build with:

1 Weemos D1 mini V2 with
1 ultrasonic sensor HC-SR04 to control the depot water level
1 rele to activate the water bomb

The main control loop will do:

Read the depot water level
Post the water level to the web server
If the water level is not between the safe range
- Stop the water bomb acting over the rele
- Post the rele value to the web server
- Send a message to alert
- Post the send message to the web server
Else
- Check the time table and if its time to start watering open the relé o if its time to stop watering close the rele
- Post the rele value to the web server
- Send a message to inform start or stop watering
- Post the send message to the web server
Sleep some seconds

SSL

Basat en el post: http://blog.mgechev.com/2014/02/19/create-https-tls-ssl-application-with-express-nodejs/ Instalem els paquetes HTTPS y FS, per implementar el servidor SSL i poder llegir els fitxers de certificats.

$ npm install --save https
$ npm install --save fs

Editem el fitxer "/bin/www", comentem:

/**
 * Create HTTP server.
 */

//var server = http.createServer(app);

Afegim

var https = require('https');
var fs = require('fs');


/**
 * Create HTTPS server.
 */

var server = https.createServer(
    {
        key: fs.readFileSync('ssl/key.pem'),
        cert: fs.readFileSync('ssl/cert.crt')
    },
    app);

Creem els certificats i els copiem a la carpeta "/ssl":

$ openssl genrsa -out key.pem \2048
$ openssl req -new -key key.pem -out csr.pem -subj "/C=<coutry code>/ST=<state>/L=<city>/O=<organization name>/OU=<organization unit> demo/CN=localhost"
$ openssl x509 -req -days 9999 -in csr.pem -signkey key.pem -out cert.crt

$ cp cert.crt /ssl
$ cp key.pem /ssl

En els fitxers de test frisby afegim la sentència següent per que no fallin en ser no confiable el certificat:

// Include this line at the beginning of your firsby test. This will direct non-rejection of SSL cert
process.env.NODE_TLS_REJECT_UNAUTHORIZED = "0";