How Whatsapp works technically..?

Every one of us is familiar with a real time messaging application Whatsapp.
It's quit interesting to know actually how the Whatsapp works. 

Whatsapp make use of Ejabberd Extensible Messaging and Presence Protocol (XMPP) server.
This server facilitates instant message transfer between two or many users at any given second. ERLANG is the programming language used by Whatsapp. Ejabberd is an open source Jabber server written in Erlang language. It was preferred by the developers of Whatsapp as it was best suited for handling huge communication system with high sustainability. Erlang also helps by quickly adapting to instant updates and hot fixes. Whatever may be the improvisations or coding improvements, Erlang helps in quickly pushing the changes to live implementation without needing restarts.
 

Whatsapp manages more than 50 billion message transfers a day. The key to the smooth data processing lies with the message queue length. The length of the message queue of all the processes associated with a node is monitored. Incase of multimedia messages, contents (audio, video, pdf, locations, contacts or image) are uploaded into a HTTP server and are linked with the content and then sent to the receiver in the form of a thumbnail. Based on the user's needs the content can either be downloaded or discarded.
XMPP is being used by Whatsapp. To ensure network security, Data security layer (DSL) is being used. This ensures private data transfer. As and when message is sent, it is queued on the server. The message waits in the queue until the recipient reconnects to receive the message. As and when a message is delivered the sender gets notified by a double check mark near the message. After the delivery the messages are instantly deleted from the server memory.
For the database management Mnesia DB comes into play. Mnesia is a multiuser distributed DBMS which happens to be the default database of ERLANG. Thus by using Mnesia, the app is able to achieve fast request responses, thereby improving the overall efficiency. Free BSD is the operating system upon which Whatsapp is laid upon.

-Mr. Gurukiran Bhat
Department of CS

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Age of the Selfie

On July 7, Russia issued a 'safe selfie' guide after 100 –odd people were injured and 10 died, this year alone, while taking selfies; a women who accidentally shot herself in the head miraculously survived. What was, until 2012, an innocuous smart phone tool now annoys as many people as it excites, riding on the increasing popularity of social media sites/ apps like facebook, twitter and instagram.

The Origin: The earliest known usage of the word 'selfie' was on an Australian online forum on September 13,2002. The selfie became popular with the INTRODUCTION OF FRONT CAMERA IN THE IPHONE 4, which was launched in june 2010. It first appeared as a hash tag on a photo-sharing site in 2004. Before the selfie craze for the 'My Space Pic'-a self portraittaken infront of the mirror and posted on Myspace.  

Where Selfies are Banned: n MECCA n La Garoupe beach, France n Running of the bulls event, Pamplona, Spain. n In august 2014, New York banned the popular 'tiger selfies'.

- Rashmi M.

II BCA

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IT Jokes

1. What did the spider do on the compute ? 
Ans: Made a website

2. What did the computer do at lunch time ? 
Ans: Had a byte!

3. What does a baby computer call his father ? 
Ans: Data !

4. Why did the computer keep sneezing ?
Ans: It had a virus !

5. What is a virus ? 
Ans: A terminal illness

6. Why was the computer cold ?
Ans :It left its windows open !

7. Why was there a bug in the computer ?
Ans :Because it was looking for a byte to eat !

8. What do you get when you cross a computer and a life guard ?
Ans: A screen saver !

- Naveena Kumar S.

  III BCA

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Programmers Prayer

Our program who are in memory.
Hello by thy name.
Thy operating system come.
Thy commands be done at the
printer as it is on the screen
Give us this day our daily data,
And forgive us our I/O errors.
As we forgive those whose logic
circuits are faulty.
Lead us not into frustration and deliver
us from power surges.
For thine is the algorithm,
The application,
And the solution,
Looping forever and ever
Return
                 

  - Nishanth Bhat

II BCA

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Raspberry Pi

As the name suggests it is names after a fruit which is Raspberry and Pi comes from mathematics.

Let’s start with what is the Raspberry Pi?

The Raspberry Pi is a low cost, credit-card sized computer that plugs into a computer monitor or TV, and uses a standard keyboard and mouse. It is a capable little device that enables people of all ages to explore computing, and to learn how to program in languages like Scratch and Python.

Being small in size you might think how much power does the Raspberry Pi use?

In a Shutdown State.
5.23 V, 0.05 Amps = 0.26 Watts.
Overall. So we can see that the new Raspberry Pi B+ uses 1.21 Watts with just keyboard dongle vs 1.89 Wattsfor the old model B. The difference, 0.68 Watts might not sound like a lot, but it's 36% less power usage.

Now you wonder what kind operating system is used for this device?

The answer would be Linux. (Being a freeware Linux can be installed and used in almost every device from desktops to mobile phones Linux can be used in almost every device.)

The Raspberry Pi can run almost any Linux distro. Most used is Arch Linux.

Now we are going to discuss about some Linux Distros used in Raspberry Pi.

1. Arch Linux

Arch Linux is a one of the most popular distro among the Linux users and also one of my favorite Distro. Initially it doesn’t contain any GUI so the user has to use correct and appropriate command to install and operate it. It uses PACMAN installation scheme, so that one can use regular apps as well as all the basic features of Pure Unix. One can install GUI if necessary. Overall if one wants to use commands for every operation this Linux distro is recommend for such Users.

2. Kali Linux

Formally Known as the Backtrack. It made from base of Debian and made for Penetration testing. It is a simple looking Linux distro but it is equipped with powerful tools used for reverse engineering, Data Mining, and often for Hacking. It uses APT installation scheme. Despite having such powerful weapons some people use this is as a daily driver. Well I am using this Distro for quite a while now. Overall it is one of most used Linux Distro for Raspberry Pi.

3. Rabian Linux

Rasbian is a version of Debian made for Raspberry Pi. All the features are same as the Debian for desktops difference is compatibility options. It uses APT installation scheme and very easy to use.

 Now let’s shed some light on Architecture of Raspberry Pi, the basic Architecture contains

• Broadcom BCM2835 (CPU & GPU)
• 256/512MB SDRAM
• 1/2 USB 2.0 Ports
• None/Ethernet Port
• HDMI port
• Audio port
• SD Card Slot and an USB slot for power

The CPU architecture of this device is

• ARM11J6JZF-S (ARM11 Family)
• ARMv6 Architecture
• Single Core
• 32-Bit RISC
• 700 MHz Clock Rate
• 8 Pipeline Stages
• Branch Prediction

Being as small as a Credit card this portable device is quite powerful. As for the price of this device is concerned it is around Rs. 2500 – 5500.  Price may wary on the specifications. Such a small machine is used for Robotics, Game emulation, Media Servers, Education (Python is the primary language used), Powerful enough to be used as a personal computer and for thousands of other projects.

Raspberry Pi was created by Eben Upton, Rob Mullins, Jack Lang and Alan Mycroft at University of Cambridge.

They, in conjunction with Pete Lomas and David Braben, formed the Raspberry Pi Foundation.

It was created to provide inexpensive programming machines to today’s youth.

It is also the smallest CPU being regularly used by millions of people around the world. It’s like a portable CPU. Just imagine walking around the streets with a heavy laptop well this is the device for the young people these days. In the end of this article I conclude that Raspberry Pi can be considered a technology of the future.

- Nishanth Bhat K
  II BCA

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