Oshani Seneviratne, Albert Au Yeung, Kenny Lu, Tim Berners-Lee
In a decentralized social networking framework, a user does not need to join any particular social networking service such as Facebook or MySpace. Instead, the user chooses a server which he trusts to host his own data such as his FOAF file, his activity log and his photo albums. Given that we refer to these files with their URIs, they can actually be stored on different servers.
We envision a user's FOAF file will play a central role in this framework. Other users who want to access this user's social network (friends list), his status, his photos, or to write on his personal messasge board, will go to his FOAF file and obtain the corresponding URIs.
By storing the data in a trusted server chosen by the user, the user are given more control over the data. The user can create access control policies using policy languages such as AIR [cite] to help restrict access to his data or applications. Such a decentralized framework also allows higher customization of the applications and interfaces. For example, users can create their own homepage which shows their social network, online activities and photos. Notice that once a FOAF compactible server software is developed, it can be installed on different servers and they can link to each other.
In the following, we describe how three popular applications in current social networking sites will look like in a decentralized version of online social networking and mention their advantages.
A wall, generally speaking, is a space where you accept information from others, and it's semi-private in the sense that you should be able to determine who can view the information on this space. Within the decentralized social networking infrastructure, you choice a server you trust to host your wall, associated with policy you prefer. Some basic options might include
Suppose your server doesn't provide the policy option that suits you, or you think it's not worth trusting, you can simply change your server. Since all the data is in the FOAF format, it shouldn't be a difficult job.
Photo updating in the dentralized setting works the same. But when you tag a person whose server B is different from the server A you sent your photo to, server A should sent a notification to server B so that server B can generate corrsponding news feed for this tagging event. Again, if your server does not meet this expectation, you can change the server.
The "News Feed" is one of the controversial features in Facebook which draws concern of privacy in social networks [cite]. Many users complain that the feature reveals too much of their activities on the social networking site. In a decentralized setting, users will be allowed more control to their own data, including the log of their activities. A news feed similar to the ones in Facebook can be provided by publishing an RSS feed and including its URI in the user's FOAF file. Subscribing to the feed is subjected to certain access control policies specified by the user. In the simplest form, an access control policy allows users who are specified as friends in the FOAF file (by using the foaf:knows property) to subscribe to the feed. It is also possible to serve different information depending on the identity of the user who submits the request. In current social networking sites, such functionalities, although possible, depend on the design of the sites which the users have little control.