7DS - Node Cooperation and Information Exchange in Mostly Disconnected Networks

When the node density in a network decreases below the level necessary to sustain ad-hoc and mesh networks, communication can succeed only by leveraging node mobility and transitioning to message-based communications. In the 7DS (Seven Degrees of Separation) project, we have been investigating how to emulate two core Internet services, namely Web access for information retrieval and email for delivering messages from mobile nodes to the Internet. We have implemented and evaluated a 7DS prototype system that leverages search, feedback and propagation limits to build a scalable system that can deliver data to and from mobile nodes. 7DS makes data exchange in disconnected networks possible by providing an application-level set of protocol services that will enable exchange of information between peer devices. It enables dynamic information exchange by using a proxy server, a multicast query system, a search engine, and a transport entity. With these entities, 7DS can perform efficient and transparent data exchange among peers in the absence of a network connection. Data exchange with the larger Internet occurs when peers enter or exit the peer network.