A unified social network service model for enhancing privacy and message gain

Social Network Services such as Facebook and Twitter are popular these days. Such SNSes are usually provided as a centralized model or a peer to peer model depending on the main objectives of the SNSes. For a high performance and robust service, the centralized model is better than the peer to peer model because all the data is stored at the server (or server farm), which can be exploited for various new services and performance enhancement. For the privacy protection, however, the peer to peer model is more helpful because the data is stored at the peers. Since each model has its own advantages and disadvantages, it is quite natural to consider a new model that exists between the two. Thus, in this paper, we first propose a unified model that incorporates both the centralized and peer to peer models. In the unified model, there can be multiple servers owned by independent service providers and the servers communicate with each other to provide the SNS to the users. We also investigate the characteristics of the unified model. Under the simple assumption that the users join the system considering the decision of their friends, we show that the users usually get together to form a nearly centralized system. This result motivates a new server selection mechanism that maximizes the privacy protection and the messaging performance.