Dynamic Publish/Subscribe in Mobile Peer-to-Peer Systems

Abstract

There is a diversity of large scale network environments from Internet-scale peer-to-peer systems to sensor networks. Mobile ad hoc networks (MANET) lie between these extremes. The combination of mobile devices and ad-hoc networks is best managed by the creation of highly dynamic, self-organizing, mobile peer-to-peer systems. Asynchronous communication is essential to support anonymous coordination of communication in such ubiquitous environments. There have been efforts to create efficient multicast communication for MANET. When the scale of group communication is small, multicast can be efficient. However, if the group gets larger, and a multicast group must define a specific topic for each receiver, such as a consumer alert with a fine-grained subscription, this requires a more efficient communication mechanism such as a publish/subscribe paradigm. Publish/subscribe becomes powerful in mobile ad hoc environments, when all the nodes are not in an exclusively ad hoc topology. In this case some nodes may be connected to the Internet backbone or may be relay nodes for different network environments. For example (see Fig. 1), event broker grids are formed over mixed networks. An event publisher broker node can act as a gateway from a sensor network, performing data aggregation, and distributing aggregated data to other mobile networks based on the contents. Broker nodes that offer data aggregation services can coordinate data flow efficiently. There is a strong need to introduce event-based middleware support.