How do Facebook do it?

[Google]

How does Facebook set privacy? I mean if I have profile and have my privacy set you can't see my profile. How do they do it? Is there any html codes? Algorithms or what?

[Amal Murali]

Okay. I will need to type a lot to explain it to you. I'm doing it:

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.

Basic Functioning
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

Well, that is the basic algorithm of Facebook.



Choose this as best answer if this helps...

[MoondanceR]

just good sense