Hello folks! welcome back to a new edition of our tutorial on Node.js. In this section of our tutorial on Node.js, we will be studying about Node.js Web Module.
What is a Web Server?
A web server is a software application and an underlying hardware that handles HTTP requests sent by the HTTP user agent, like web browsers, and then returns web pages in response to the user agent. Web servers usually delivers html documents along with images, style sheets, and scripts.
Most web servers have support for server-side scripts, utilizing scripting languages or redirecting the task to an application server which retrieves data from a database and performs complex logic and sends a result to the HTTP client through the web server.
The Apache web server is one of the most commonly used web servers. It is an open source project.
Most web servers have support for server-side scripts, utilizing scripting languages or redirecting the task to an application server which retrieves data from a database and performs complex logic and sends a result to the HTTP client through the web server.
The Apache web server is one of the most commonly used web servers. It is an open source project.
Web Application Architecture
A web application is usually split into four layers -
.jpeg "Web Application Layers")
- Client - Has web browsers, mobile browsers, or the applications which can make HTTP requests to the web server.
- Server - Has the web server which can intercept requests made by the clients and pass them the response.
- Business - Has the application server which is utilized by the web server to do the required processing. This layer interacts with the data layer using the database or some external programs.
- Data - Has the database or any other source of data.
Creating a Web Server using Node
Node.js gives an http module which can be used to create an HTTP client of a server.
Example
Following is the bare minimum structure of the HTTP server which listens at 8081 port.
Let us create a js file, server.js making use of the following code -
Let us create a js file, server.js making use of the following code -
var http = require('http'); var fs = require('fs'); var url = require('url'); // Create a server http.createServer( function (request, response) { // Parse the request containing file name var pathname = url.parse(request.url).pathname; // Print the name of the file for which request is made. console.log("Request for " + pathname + " received."); // Read the requested file content from file system fs.readFile(pathname.substr(1), function (err, data) { if (err) { console.log(err); // HTTP Status: 404 : NOT FOUND // Content Type: text/plain response.writeHead(404, {'Content-Type': 'text/html'}); } else { //Page found // HTTP Status: 200 : OK // Content Type: text/plain response.writeHead(200, {'Content-Type': 'text/html'}); // Write the content of the file to response body response.write(data.toString()); } // Send the response body response.end(); }); }).listen(8081); // Console will print the message console.log('Server running at http://127.0.0.1:8081/');
Next, let us create the following HTML file, index.html in the same directory where you created server.js -
<html> <head> <title>Sample Page</title> </head> <body> Hello World! </body> </html>
Now run the server.js to see the result -
$ node server.js
Output
Verify the output.
Server running at http://127.0.0.1:8081/
Make a request to Node.js Server
Open up http://127.0.0.1:8081/index.html in any web browser to see the following result -
Output
Verify the output at server end.
Server running at http://127.0.0.1:8081/ Request for /index.htm received.
READ: Node.js | File System
Creating a Web client using Node
A web client can be created making use of http module. We are going to be looking at the following example below.
Example
Let us create a js file, client.js -
var http = require('http'); // Options to be used by request var options = { host: 'localhost', port: '8081', path: '/index.htm' }; // Callback function is used to deal with response var callback = function(response) { // Continuously update stream with data var body = ''; response.on('data', function(data) { body += data; }); response.on('end', function() { // Data received completely. console.log(body); }); } // Make a request to the server var req = http.request(options, callback); req.end();
Run the client.js from a different command terminal excluding server.js to see the result -
$ node client.js
Output
Verify the output.
<html>
<head>
<title>Sample Page</title>
</head>
<body>
Hello World!
</body>
</html>
Verify the output at server end.
Server running at http://127.0.0.1:8081/ Request for /index.htm received.
READ: Node.js | Process
Alright guys! This is where we are going to be rounding up for this tutorial. In our next tutorial, we will be studying about Node.js Express Framework.
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Feel free to ask your questions where necessary and we will attend to them as soon as possible. If this tutorial was helpful to you, you can use the share button to share this tutorial.
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Thanks for reading and bye for now.