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Step 2 - Building the server

What is a server?

  • Servers are computer programs that receive requests from other programs, the clients and send back a response e.g share data, information or hardware and software resources.

...and what is a server in plain English?

  • A server is a computer program. Its job is to send and receive data.

  • Let's take a website for example. A website is just a collection of HTML and CSS files, images, maybe some javascript files.

  • When you type a website address in your browser's address bar, the browser (client) sends a request to the server that lives at that address.

  • The browser asks the server to give it the files it needs to display the website properly.

Server flow

1. Understanding 'modules'

What's a module?

Modules are just small programs you can integrate with the bigger program you are writing.

Modules would be listed in your package.json.

There are 3 types of modules.

a. Node core module

'Core' Node modules come with Node automatically. Examples of common core modules are http, fs and path.

There is a list of all the core modules and their methods on the Node.js website.

b. Node 3rd-party module

There are thousands of open-source, 3rd-party Node modules that other clever people have written. You can download useful 3rd-party modules (also known as "packages") from npm (the node package manager).

The npm website says:

npm makes it easy for JavaScript developers to share and reuse code, and it makes it easy to update the code that you're sharing.

The npm command-line tool comes automatically with Node. You can install 3rd-party packages on the command line, so no need to download from the npm website or anything.

c. Modules you've written

Also called a module, but slightly different from the first two.

These are modules you write yourself in your code. We will talk about this later on in step 7.

Time to code!!!

2. require the http core module

For our server, we are going to use a core Node module called http.

http is a useful core module - it helps us process our server requests and responses. Just like other modules, http is a big JavaScript object containing properties and methods (functions) that we can use.

The official reference to the http module can be found on the Node.js website here.

Create a file called server.js

Inside server.js, write the following:

var http = require('http');

In Node, you access modules in your project by 'requiring' them.

3. Initialise the server

To build our server, we will use a specific method, http.createServer.

Add the following line to server.js:

var http = require('http');

var server = http.createServer();

4. Start 'listening' for potential requests

One more step left, we need to set a port for our server to listen to. Think of a port as a door number; any requests that come to the server will come via that door.

We use the server.listen method to do this. It will take two arguments, a port and a callback function.

var http = require('http');

var server = http.createServer();

server.listen(3000, function () {

    console.log("Server is listening on port 3000.  Ready to accept requests!");
});

5. Switch the server on!

You've built your server, but it isn't running yet. We will use the node keyword to run the server file.

To do so, type this command in your command line:

node server.js

If you see this...

success

Congratulations!

You have built yourself a server!

Commit your changes

git add .
git commit -m 'enter relevant message'

next step >>>

Keywords

  • server
  • client
  • request
  • response
  • require
  • module
  • method
  • port