Using multiple processes is the best way to scale a Node application. Node.js is designed for building distributed applications with many nodes. This is why it’s named Node. Scalability is baked into the platform and it’s not something you start thinking about later in the lifetime of an application.

In this article we look at how to create a basic child process which can be used to run long-running processes in the background.

Fork A Process

Let’s consider a process in which an array is iterated over and the data is acted upon. To do this basically we will be forking a child process with the in-built child_process module to send the data to a worker file.

var cp = require('child_process');
var child = cp.fork('./worker');
var obj = [1,2,3,4,5];
child.send(obj);

A QR (Quick Response) code is a type of a barcode which is used to store information is a visual machine-learning format. QR Code is being used extensively in a lot of industries for various applications.

QR codes can be used effectively in marketing as well. For e.g., a URL or Visiting Card information can be stored in a QR code, which when scanned from a phone camera, can either redirect to the said URL or store personal details to your phone contacts respectively.

Let’s see the various QR code information data format which can be embedded.

1] Embed URL

A site URL or site address can be embedded into a QR code. Some of the QR code scanner application in your phones can read this QR code and automatically open up a browser redirecting to the URL that is embedded.

The QR code information data format to be embedded as URL is as follows

http://codincafe.com

SMSTO:+1123456:

Like the above example, this QR code only have the phone number. The user is free to write their own text content and the number from the QR code will be pre-filled.

3] vCard Data

vCard or VCF (Virtual Contact File), is a file format standard for electronic business cards. This can be embedded in a QR code so that when scanned, the contact information within it like name, email, phone number etc. can be parsed by a QR code scanner and can be saved in your phone or call the number etc.

Most of the QR code scanners will support vCard version 3.0 and higher.

The QR code information data format to be embedded as vCars is as follows

vCard V3.0

BEGIN:VCARD
VERSION:3.0
N:Gump;Forrest;;Mr.;
FN:Forrest Gump
ORG:Bubba Gump Shrimp Co.
TITLE:Shrimp Man
PHOTO;VALUE=URI;TYPE=GIF:http://www.example.com/dir_photos/my_photo.gif
TEL;TYPE=WORK,VOICE:(111) 555-1212
TEL;TYPE=HOME,VOICE:(404) 555-1212
ADR;TYPE=WORK,PREF:;;100 Waters Edge;Baytown;LA;30314;United States of America
LABEL;TYPE=WORK,PREF:100 Waters Edge\nBaytown\, LA 30314\nUnited States of America
ADR;TYPE=HOME:;;42 Plantation St.;Baytown;LA;30314;United States of America
LABEL;TYPE=HOME:42 Plantation St.\nBaytown\, LA 30314\nUnited States of America
EMAIL:forrestgump@example.com
REV:2008-04-24T19:52:43Z
END:VCARD

You may have heard of, bought or thinking of doing a project on RaspberryPi to enter the world of IoT. RaspberryPi is the first step to dive in head first into Internet of Things. It is the most simplest piece of technology that you can get your hands on to develop quick and efficient prototypes.

IoT devices are generally small and basic equipments, most of the times without event a display. Most of the times you will be using RaspberryPi as well, without a display or a monitor. You need to remotely access these computers to configure them and work your way up.

The makers of RaspberryPi provides – Raspbian Linux, which is a Debian based operating system. It is the official Linux version which has been recommended to be used. Installing Raspbian is very easy with the right tools and experience.

To start with a basic Raspbian installation, you would need the following:

Hardware

• RaspberryPi
• 8 GB Class 10 SD Card (I recommend 32 GB as they are quite cheaper now a days)
• SD Card Adapter / Reader

Software

• Raspbian Linux
• Etcher – This program is used to burn Raspbian Linux to you SD card.

Please note: The above links to Amazon.com are my affiliate links. This helps us to keep the blog alive!

• In the first step select the Raspbian image which was downloaded from Step 1
• In the next step, select the USB card reader device where the SD card is placed to burn the operating system
• In the last step confirm your settings and let the program create the Raspbian disk.
• Once the OS is burned to the SD card, there are 2 things which you need to follow to make your life easier. These are a) Enable SSH and b) Preload WiFi credentials so that RaspberryPi is connect to your network as soon as it is powered on. These steps are mentioned below

Enable SSH

For headless setup, SSH can be enabled by placing a file named ssh, without any extension, onto the boot partition of the SD card from another computer. When the Pi boots, it looks for the ssh file. If it is found, SSH is enabled and the file is deleted. The content of the file does not matter; it could contain text, or nothing at all.
Source: https://www.raspberrypi.org/documentation/remote-access/ssh/

If you have loaded Raspbian onto a blank SD card, you will have two partitions. The first one, which is the smaller one, is the boot partition. Place the file into this one.

Preload WiFi Credentials

Create a file in this directory called wpa_supplicant.conf onto the boot partition of the SD card. The file should contain the following details:

 ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
 network={
     ssid="YOUR_NETWORK_NAME"
     psk="YOUR_PASSWORD"
     key_mgmt=WPA-PSK
 }

Source: https://howchoo.com/g/ndy1zte2yjn/how-to-set-up-wifi-on-your-raspberry-pi-without-ethernet

And that’s it folks! Now insert your SD card in RaspberryPi and power it on. Wait for a few minutes for it to setup. You can check in your router page to a new device and get its IP address. You can now ssh into your Pi with the default username pi and password raspberry

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Nginx has become the most important player in web server’s. With very low footprint and easy virtual host configuration, Nginx is becoming more and more popular among Developers and System Admins.

There is a lot of struggle when it comes to configure Nginx with Node.js. A Node.js app can be started on any free port that is not in use and it is a web server in itself. But there are a couple of drawbacks in using Node.js as raw web server. Hence here comes the need for Nginx to act as reverse proxy.

In a typical Nginx + Node.js environment, Nginx is installed to listen to the port 80 to serve http or port 443 to serve https requests and forward the request to the Node.js application on the laters specific port.

Below is a gist for the server block configuration for Nginx that can we use to reverse proxy a Node.js app.

server {
  listen        PUBLIC_IP:80;
  server_name   example.com www.example.com;
	  location / {
	  	proxy_pass      http://PUBLIC_IP:5001;
		root           /home/admin/web/example.com/public_html;
	  }
}

node.js is still considered to be the new mischievous kid on the block.

node.js is an event-driven JavaScript platform. It is a light-weight and efficient framework. Its efficiency in terms of speed and and high throughput has been derived due to its non-blocking (aka Asynchronous) I/O model.

Along with many things Node.js can be used as a web server. This tutorial explains how to create a simple HTTP server with node.js which gives a 200 status OK page with some content.

Please note: You must need node.js installed to start with this tutorial. You can download the flavor of node.js of your choice from here https://nodejs.org/en/download/

Getting Started

Once you have installed node.js, its time to get started.

First lets create a directory.

$ mkdir myNodeApp