One of the very many cool things about node.js, is that it makes it possible to easily create really simple event driven applications with very few lines of code.
You’ll also need to ensure you have node installed on your machine, Check out my post for instructions on how to install node.js on ubuntu desktop.
If you understand the basics of Node.js, you’ll know that Node.js has a simple module loading system. In Node.js, files and modules are in one-to-one correspondence and each file is treated as a separate module).
One of these Node.js modules is the
http module which helps to manipulate and handle the HTTP
response . http messages.
For a detailed discussion about this API check out Node.js v8.2.0 Documentation.
As you can see there is not a lot of code to write to create this little web server. All we’ve done here is referenced the http module created a server and set it to listen on port 3939.
In order to run the webserver just go to your command line and invoke it with the following
Once you have executed the command you computer will now have a web server running on port 3939. You can test this web server using two methods.
The first method is to open a web browser i.e. Google Chrome, Safari or Firefox etc. and navigate to to http://localhost:3939
You’ll notice the little web server responds and the web page is displayed.
The second method you can test is by using a command-line program
curl, which most Mac and Linux machines have pre-installed. Open a terminal window and type
You should now see something similar to the following
As you can see we’ve created a pretty cool a web server in just 9 lines of code! Obviously it doesn’t pack all the features of Apache etc, but it still is a handy little web server. At the moment it only has one route and you can’t really do anything else with it, but from this point on we can scale it a bit more.
Node.js provides a lot of powerful functionality out of the box, and as we can see in the first line of the previous code, you can use one of the built-in modules – the http module, which allows your app as a web server. The require function includes this function and we created a variable of http to refer to it.
The createServer function takes only one argument, a function that will be called whenever somebody makes a connection to your server. You will typically pass a ServerRequest and a ServerResponse objects to the function. Once the server is created, you tell it to start listening for requests on a particular port – in our case we used 3939 – when you launch the program.
To stop the web server, go back to the command line and CTRL + C
Lets now make it a little more complicated and enable it to handle a few more routes and create a log entry if somebody tries to browse to a route it doesn’t know about. We are now going to start diving into some basic features that make node so extensible. We start using the Node Package Manager (NPM)
What is NPM ?
A detailed discussion of NPM is beyond the scope of this post, but I recommend you visit the great tutorials at https://docs.npmjs.com/getting-started/what-is-npm or watch this short video will give you most of the information you’ll need.
A logging web server
In order to create a logging web server we are going to use an existing library within NPM called
log4js. First we’ll need to configure our application to use
We’ll answer all the questions, don’t worry too much about what all these mean right now, and we will be able to edit the answers we provide later. Once the command has finished executing you will notice a new file and a new directory appear in your directory.
I’ll explain more about these files in a later tutorial but for now feel free to explore the file and directory. You’ll see the file will contain all the answers to the questions you answered during the previous step.
The next step will be to import the log4js file into your project. To do this we will execute another line in the terminal window
We’ll need to create a new directory in our project folder , and call it logs.
We’ll also need to create a reference to log4js module and configure it to create an error log file. We’ll also add a basic switch statement to handle a few basic routes, with a default which handles a basic 404 error. The completed code looks like this.
Now if we run the application, the same as before we start and navigate to the website, we’ll start seeing a bit more output on the command line and if you navigate to the logs folder you’ll notice a log file created with some entries. Try accessing some of the routes and try entering a route that doesn’t exist.
The log file will also have similar entries appended
I’d admit this particular webserver is lacking some enterprise scale functionality, but at its root it is still a webserver and it can be used as a starting point for building a more complex little tool.
As you can see by this short example, that node is extremely scalable and by simply adding a reference to an existing module within the node package manager we can very quickly add and use other libraries to further expand on our existing application.
Node.JS enables developers to turn any server into a lightweight webserver with just a few lines of code. It’s perfect for developing small lightweight event driven web applications, without having to concerns ourselves with all the infrastructure plumbing required.
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