TACO-DTN: a time-aware content-based dissemination system for delay tolerant networks

Content dissemination applications are becoming more and more popular on fixed infrastructure: in this paper we introduce TACO-DTN, a content dissemination system which, by virtue of being time-aware in terms of subscriptions and events, is appropriate for delay tolerant networks, where a number of nodes act as infostations, enjoying some form of connectivity to the backbone, and other nodes are mobile devices, reachable sometimes only through intermittent connectivity of carriers. Examples of applications benefiting from such a system could be travel information dissemination systems in large cities (exploiting infostations at bus stops) or on highways, advertisements dissemination at specific times, and information dissemination to remote villages. The approach is based on a novel concept of temporal utility of subscriptions and events. The temporal utility is used to govern the routing of the events to the right infostation (i.e., the one reached by the interested subscribers at the right time), avoiding unnecessary information transfer on slow links and the buffer management, in case buffer limitations are an issue. We give a description of our protocol and discuss its validation through simulation.