IDG2001 course - Assignment 2

Project to IDG2001 class at NTNU. It should simulate MQTT messaging between publishers (smart sensors), broker and subscribers.

Quick start

Get started in several quick steps

1. Install dependencies

npm install

2. Enter your DB_URL in .env

DB_URL = '<ENTER YOUR DB_URL>'
// mongodb+srv://<user>:<password>@<cluster_hostname>/<DB_name>?retryWrites=true&w=majority

3. Start the broker

npm start

4. Add a sensor (publisher)

• Open a new terminal window

node ./Class/publisher.js

5. Add a client (subscriber)

• Open a new terminal window

node ./Class/subscriber.js

Event listeners of the Aedes Broker

• Event 'client':
  • When a client connects to the broker ('connect' event initiated by the client)
• Event 'subscribe':
  • When a client subscribes to one or more topics ('subscribe' event initiated by the client)
  • Stores the client in mongoDB to collection Subscribers with topics it had subscribed to (if it does not exist yet)
• Event 'publish':
  • When a client publishes a message to the broker ('publish' event initiated by the client)
  • Converts message to JSON - differs through contentType
  • Stores the publisher in mongoDB to collection Publishers (if it does not exist yet)
  • Stores the message in mongoDB to collection Messages
• Event 'unsubscribe':
  • When a client unsubscribes from one or more topics
• Event 'clientDisconnect':
  • When a client disconnects from the broker (closing the terminal window with pub/sub)
  • Deletes publisher/subscriber from Publishers/Subscribers collection respectively

Publisher

Publishers have a choice of connecting to eiter one of the rooms below. Then the code chooses randomly which format of the message it will be sending from messageTypes:

const rooms = ['Bedroom', 'Garage', 'LivingRoom', 'Basement'];
const messageTypes = ['senml+json', 'senml+xml', 'senml+exi'];

You can start one or more publishers. When starting a publisher.js:

1. Enter name of the publisher (sensor),
2. Enter a topic to which you want the sensor to connect,
3. Enter the contentType of the messages sensor should send,
4. Enter a unit reported by the sensor,
5. The publisher starts sending messages every 7.5 seconds to the broker in format:

{
  contentType: `application/${this.payload}`,
  data: {
    bn: client.options.clientId,
    u: this.unit,
    n: this.name,
    v: getRandomIntInRange(-5, 35),
    t: Date.now()
  }
}

Subscriber

Subsribers have a choice of connecting to any of the topics below. You can choose more than one topic. Then the code starts to listen to any of the messages published by a publisher.

const rooms = ['Bedroom', 'Garage', 'LivingRoom', 'Basement'];

You can start one or more subscribers. When starting a subscriber.js:

1. Enter subscriber name,
2. Enter one or more topics,
3. The subscriber starts to listen to the broker and receives messages destined to the topics it subscribed to.