DCCS-API-js

This git hub shows how an edge device to connect to WISE-PaaS IoT Hub service remotely and securely via DCCS api.

A secure method

Normally, if we are a developer of a WISE-PaaS application, we may have access to all the service credentials on the WISE-PaaS Management Portal. However, if we are now providing a service, we won't want our users to hard-code the uri in the code, because this may lead to privacy issues and security breaches. Therefore, as a service provider, we give out service keys. These keys are genuinely confidential and only authorized personnel could have access to it.

Step-by-step

Once we have the key, we may retreive service credentials via DCCS API. See more DCCS Documentation.

STEP1 Install node modules

npm install

NOTE: If you want to add any other packages during your development,

use the command npm install --save {nodeModuleName}

STEP2 Create a key file

This file could by a txt file or whatever file you prefer, but remember that the format must be like how you define a string type variable:

variableName = 'key'

STEP3 Require the file in your code

For example:

require('./fileName');
const codeVariable = variableName;

Now, you have access to the key in the code.

Code Description

const DCCSUrl = 'https://api-dccs.wise-paas.io/v1/serviceCredentials/' + DCCSKEY;

NOTE: This is the api url to retreive credentials of the service. If you wish to come up with other functions, see DCCS Documentation.

async function createMockTemp(){
    //await the response of the fetch call
    let response = await fetch(DCCSUrl)
    //proceed once the first promise is resolved.
    let data = await response.json();
    //proceed only when the second promise is resolved
    let uri = data.credential.protocols.mqtt.uri
    let correctUri = uri.replace(data.credential.hostname, data.credential.externalHosts)
    return correctUri;
}

NOTE: This is the most tricky part of the code is that Javascript is an asynchronous language, which means that it does not execute the code in order. However, the node-fetch package we use, would need some time to retreive data from the internet and may not be done before other commands in the code. Therefore we need to use an async function in our code.

createMockHumi()
  .then(function(mqttUri){
    console.log('=*=*=*=*=*=URI=*=*=*=*=*=');
    console.log(mqttUri);
    console.log('=*=*=*=*=*=URI=*=*=*=*=*=');
    const client = mqtt.connect(mqttUri);

    // Use mqttUri or connectOpts
    client.on('connect', (connack) => {
      setInterval(() => {
        publishMockHumi();
      }, 3000);
    });
    // Publish mock random humidity periodically
    function publishMockHumi() {
      const humi = Math.floor((Math.random() * 6) + 50);
      
      client.publish('livingroom/humidity', humi.toString(), { qos: 2 }, (err, packet) => {
        if (!err) console.log('Data sent to livingroom/humidity -- ' + humi);
      });
    }
  })

NOTE: In the async function above, it has a return of the uri we require to connect to the IoT Hub service. We need to make sure we get the uri before we start publishing data. So, we need a promise function to make sure that the codes are fully executed and we get the parameter, .then() execute the code in this promise function.