How I simply integrate a Node module into Wakanda!

Thanks to the new feature NodeWorker developed by Wakanda teams, it becomes now possible to have full benefit of any Node package module into a Wakanda application.

npm into wakanda

Let’s think about a situation where we need to use a Node module in a Wakanda backend project.

For example, in my Wakanda application I need to check the code of a visa credit card passed into a url as a query string to check if it is valid or not. To check the visa code, we will use a node package module called visa-validation, this npm is able to check the credit card number validity, the expiration date and also the cvv validity.

Create the request handler

After creating a backend project, we will create a requesthandler that will call the function responsible for creating the node worker. Into bootstrap.js we will add this line of code:

httpServer.addRequestHandler('/verify-visa', 'handler.js', 'check');

Create a handler

Then we will need to add a file called handler.js that will contain the function check() which will be responsible for creating a nodeWoker where we will require the visa-validation module.

var check = function(req, res){
	var myWorker = new NodeWorker( './node-worker.js', 'my-worker');
	var result;
	var query = req.urlQuery;
	var query = query.substr(5);
	myWorker.port.postMessage(query);
	myWorker.port.onmessage = function(event){
		result = event.data;	
	}
	wait(1000);
	if(result === true)	
		return 'The result is ' + result +', your visa credit card is valid'
	if(result === false) 
		return 'The result is ' + result +', your visa credit card is not valid'
}

Create the node worker of visa validation

We will need to install the node module into the backend folder. So in our terminal we will have to insert those commands

cd backend
npm install visa-validation --save

And here is the code defining how the Node module will be required into the file node-worker.js.

var visaCard = requireNode('visa-validation');

onconnect = function(connectEvent) {

    var workerPort = connectEvent.ports[0];
    
    workerPort.onmessage = function(event){
    	var validation = visaCard.isValidCardNumber(event.data);
    	workerPort.postMessage( validation );
		close();
    }
}

How it works?

When the request handler is called through the browser via this link:

http://127.0.0.1:8081/verify-visa?code=4916396764746993

That means that the function check(req, res) contained into handler.js is called automatically and it will instantiate the node worker present on the node-worker.js.

var myWorker = new NodeWorker( './node-worker.js', 'my-worker');

Then it will get the parameter on the query string, so it can post it to the node worker.

myWorker.port.postMessage(query);

On the other side, when the node worker is created it waits for an event from the handler. When it receives the message that it is waiting for, it posts a response containing the result of the visa-validation node module and finally closes the node worker.

workerPort.onmessage = function(event){
    	var validation = visaCard.isValidCardNumber(event.data);
    	workerPort.postMessage( validation );
		close();
   }

We should also not forget to add a wait() in handler.js so it can be able to receive the response from the node worker before its context is killed. At the end, the check() function will return the node worker response as a result, so it can display it on the browser.

thelbouffi / wakanda-node