HOW DOES FACEBOOK WORKS >>>

Facebook is social networking. People have been “facebooking” each other for about 6 years now, making Facebook the most used social network with over 350 million users worldwide. But how does Facebook work?
In this article, I will discuss Facebook’s inner workings, covering its architecture and frontend/backend infrastructure””the nuts and bolts that hold Facebook together.

How Does Facebook Work?””The Front End

Facebook uses a variety of services, tools, and programming languages to make up its core infrastructure. At the front end, their servers run a LAMP (Linux, Apache, MySQL, and PHP) stack with Memcache. Not a computer science expert? Let’s take a look at exactly what that means.

Linux & Apache

This part is pretty self-explanatory. Linux is a Unix-like computer operating system kernel. It’s open source, very customizable, and good for security. Facebook runs the Linux operating system on Apache HTTP Servers. Apache is also free and is the most popular open source web server in use.

MySQL

For the database, Facebook utilizes MySQL because of its speed and reliability. MySQL is used primarily as a key-value store as data is randomly distributed amongst a large set of logical instances. These logical instances are spread out across physical nodes and load balancing is done at the physical node level.
As far as customizations are concerned, Facebook has developed a custom partitioning scheme in which a global ID is assigned to all data. They also have a custom archiving scheme that is based on how frequent and recent data is on a per-user basis. Most data is distributed randomly.

PHP

Facebook uses PHP because it is a good web programming language with extensive support and an active developer community and it is good for rapid iteration. PHP is a dynamically typed/interpreted scripting language.

Memcache

Memcache is a memory caching system that is used to speed up dynamic database-driven websites (like Facebook) by caching data and objects in RAM to reduce reading time. Memcache is Facebook’s primary form of caching and helps alleviate the database load.
Having a caching system allows Facebook to be as fast as it is at recalling your data. If it doesn’t have to go to the database it will just fetch your data from the cache based on your user ID.

Downsides to Using LAMP

Facebook has realized that there are downsides to using the LAMP stack. Notably, PHP is not necessarily optimized for large websites and therefore hard to scale. Also, it is not the fastest executing language and the extension framework is difficult to use.

Mike Schroepfer, Facebook’s Vice President of Engineering, recently did an interview at EmTech@MIT concerning this. “Scaling any website is a challenge,” Schroepfer said, “but scaling a social network has unique challenges.”
He went on to say that unlike other websites, you can’t just add more servers to solve the problem because of Facebook’s “huge interconnected dataset.” New connections are created all the time due to user activity.
Facebook has grown so quickly that they are often faced with issues regarding database queries, caching, and storage of data. Their database is huge and largely complex. To account for this, Facebook has started a lot of open source projects and backend services.

How Does Facebook Work?””The Back End

Facebook’s backend services are written in a variety of different programming languages including C++, Java, Python, and Erlang. Their philosophy for the creation of services is as follows:
1. Create a service if needed
2. Create a framework/toolset for easier creation of services
3. Use the right programming language for the task
A list of all of Facebook’s open source developments can be found here. I will discuss a few of the essential tools that Facebook has developed.

Thrift (protocol)

Thrift is a lightweight remote procedure call framework for scalable cross-language services development. Thrift supports C++, PHP, Python, Perl, Java, Ruby, Erlang, and others. It’s quick, saves development time, and provides a division of labor of work on high-performance servers and applications.

Scribe (log server)

Scribe is a server for aggregating log data streamed in real-time from many other servers. It is a scalable framework useful for logging a wide array of data. It is built on top of Thrift.

Cassandra (database)

Cassandra is a database management system designed to handle large amounts of data spread out across many servers. It powers Facebook’s Inbox Search feature and provides a structured key-value store with eventual consistency.

HipHop for PHP

HipHop for PHP is a source code transformer for PHP script code and was created to save server resources. HipHop transforms PHP source code into optimized C++. After doing this, it uses g++ to compile it to machine code.

Conclusion

In a nutshell, that’s Facebook. This article could easily be 37 pages longer if I were to go into more detail, but to answer the question “How does Facebook work?” I think this will suffice. If you look past all of the features and innovations the main idea behind Facebook is really very basic””keeping people connected. Facebook realizes the power of social networking and is constantly innovating to keep their service the best in the business.

What technology using in GOOGLE search engine..

The technology behind Google's great results
As a Google user, you're familiar with the speed and accuracy of a Google search. How exactly does Google manage to find the right results for every query as quickly as it does? The heart of Google's search technology is PigeonRank™, a system for ranking web pages developed by Google founders Larry Page and Sergey Brin at Stanford University.


Building upon the breakthrough work of B. F. Skinner

 

, Page and Brin reasoned that low cost pigeon clusters (PCs) could be used to compute the relative value of web pages faster than human editors or machine-based algorithms. And while Google has dozens of engineers working to improve every aspect of our service on a daily basis, PigeonRank continues to provide the basis for all of our web search tools.
Why Google's patented PigeonRank™ works so well
PigeonRank's success relies primarily on the superior trainability of the domestic pigeon (Columba livia) and its unique capacity to recognize objects regardless of spatial orientation. The common gray pigeon can easily distinguish among items displaying only the minutest differences, an ability that enables it to select relevant web sites from among thousands of similar pages.
By collecting flocks of pigeons in dense clusters, Google is able to process search queries at speeds superior to traditional search engines, which typically rely on birds of prey, brooding hens or slow-moving waterfowl to do their relevance rankings.
When a search query is submitted to Google, it is routed to a data coop where monitors flash result pages at blazing speeds. When a relevant result is observed by one of the pigeons in the cluster, it strikes a rubber-coated steel bar with its beak, which assigns the page a PigeonRank value of one. For each peck, the PigeonRank increases. Those pages receiving the most pecks, are returned at the top of the user's results page with the other results displayed in pecking order.
Integrity
Google's pigeon-driven methods make tampering with our results extremely difficult. While some unscrupulous websites have tried to boost their ranking by including images on their pages of bread crumbs, bird seed and parrots posing seductively in resplendent plumage, Google's PigeonRank technology cannot be deceived by these techniques. A Google search is an easy, honest and objective way to find high-quality websites with information relevant to your search.
Data
PigeonRank Frequently Asked Questions
How was PigeonRank developed?

The ease of training pigeons was documented early in the annals of science and fully explored by noted psychologist B.F. Skinner, who demonstrated that with only minor incentives, pigeons could be trained to execute complex tasks such as playing ping pong, piloting bombs or revising the Abatements, Credits and Refunds section

 

of the national tax code.

Brin and Page were the first to recognize that this adaptability could be harnessed through massively parallel pecking to solve complex problems, such as ordering large datasets or ordering pizza for large groups of engineers. Page and Brin experimented with numerous avian motivators before settling on a combination of linseed and flax (lin/ax) that not only offered superior performance, but could be gathered at no cost from nearby open space preserves. This open space lin/ax powers Google's operations to this day, and a visit to the data coop reveals pigeons happily pecking away at lin/ax kernels and seeds.

What are the challenges of operating so many pigeon clusters (PCs)?

Pigeons naturally operate in dense populations, as anyone holding a pack of peanuts in an urban plaza is aware. This compactability enables Google to pack enormous numbers of processors into small spaces, with rack after rack stacked up in our data coops. While this is optimal from the standpoint of space conservation and pigeon contentment, it does create issues during molting season, when large fans must be brought in to blow feathers out of the data coop. Removal of other pigeon byproducts was a greater challenge, until Page and Brin developed groundbreaking technology for converting poop to pixels, the tiny dots that make up a monitor's display. The clean white background of Google's home page is powered by this renewable process.

Aren't pigeons really stupid? How do they do this?

While no pigeon has actually been confirmed for a seat on the Supreme Court, pigeons are surprisingly adept at making instant judgments when confronted with difficult choices. This makes them suitable for any job requiring accurate and authoritative decision-making under pressure. Among the positions in which pigeons have served capably are replacement air traffic controllers, butterfly ballot counters and pro football referees during the "no-instant replay" years.

Where does Google get its pigeons? Some special breeding lab?

Google uses only low-cost, off-the-street pigeons for its clusters. Gathered from city parks and plazas by Google's pack of more than 50 Phds (Pigeon-harvesting dogs), the pigeons are given a quick orientation on web site relevance and assigned to an appropriate data coop.

Isn't it cruel to keep pigeons penned up in tiny data coops?

Google exceeds all international standards for the ethical treatment of its pigeon personnel. Not only are they given free range of the coop and its window ledges, special break rooms have been set up for their convenience. These rooms are stocked with an assortment of delectable seeds and grains and feature the finest in European statuary for roosting.

Dropbox...

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