Social network applications are becoming increasingly popular on mobile devices. A mobile presence service is an essential component of a social network application because it maintains each mobile user’s presence information, such as the current status (online/offline), GPS location and network address, and also updates the user’s online friends with the information continually.
the system model, and the buddy-list search problem. The geographically distributed presence servers to form a server to- server overlay network. The ubiquity of the Internet, mobile devices
and cloud computing environments can provide presence-enabled applications, social network applications/services, worldwide. Facebook, Twitter, Foursquare, Google Latitude, buddycloud and Mobile Instant Messaging (MIM) , are examples of presence-enabled applications that have grown rapidly in the last decade.The future, mobile devices will become more powerful, sensing and media capture devices. It is inevitable that social network services will be the next generation of mobile Internet applications. A mobile presence service is an essential component of social network services in cloud computing environments. The key function of a mobile presence service is to maintain an up-to-date list of presence information of all mobile users. The server architectures of existing presence services, and introduce the buddy-list search problem in distributed presence architectures in large-scale geographically data centers. The buddy-list search problem is a scalability problem that occurs when a distributed presence service is overloaded with buddy search messages. The buddy list searching algorithm of Presence Cloud coupled with the two-hop overlay and one-hop caching strategy ensures that Presence Cloud can typically provide swift responses for a large number of mobile users.