I. Introduction
Advanced features of social networking such as content recommendation and community based environment enhance people's communications and access to the information. Along with the wave of web 2.0, plenty of social networking applications are popped out in the internet. Today, Facebook with around 300 millions active users [2] is the most visited web-site per day in the internet. Moreover, P2P technologies have been very popular during last decade and accounted around 20% of the internet traffic.