Opportunistic Overlays: Efficient Content Delivery in Mobile Ad Hoc Networks

Abstract

Abstract. Current content-based publish/subscribe systems assume network environments with stable nodes and network topologies. For mobile environments, one resulting problem is a mismatch between static broker topologies and dynamic underlying network topologies. This mismatch will result in inefficiencies in event delivery, especially in mobile ad hoc networks where nodes frequently change their locations. This paper presents a novel middleware approach termed opportunistic overlays, and its dynamically reconfigurable support framework to address such inefficiencies introduced by node mobility in publish/subscribe systems. The opportunistic overlay approach dynamically adapts event dissemination structures (i.e., broker overlays) to changes in physical network topology, in nodes' physical locations, and in network node behaviors, with the goal of optimizing end-to-end delays in event delivery. Runtime adaptations include the dynamic construction of broker overlay networks and changes of mobile clients' assignments to brokers. Experimental results demonstrate that the opportunistic overlay approach is practically applicable and that the performance advantages attained from the use of opportunistic overlays can be substantial.

Load Balancing Content-Based Publish/Subscribe Systems

“…Consequently, the farther the publication travels, the higher is the delivery delay. The overlay of filter-based approaches may consist of either a set of dedicated brokers [Banavar et al 1999;Carzaniga et al 2001;Chen and Schwan 2005;Cugola et al 2001;Mühl 2001;Li et al 2008b;MSRG 2008;Pallickara and Fox 2003;Pietzuch and Bacon 2002;Segall and Arnold 1997] or purely clients [Aekaterinidis and Triantafillou 2006;Baldoni et al 2005;Castelli et al 2008;Chand and Felber 2005;Gupta et al 2004;Patel et al 2009;Tam et al 2003;Terpstra et al 2003;Triantafillou and Aekaterinidis 2004;Voulgaris et al 2006;Zhang et al 2005;Zhu and Hu 2007]. In the multicast-based approach [Adler et al 2001;Casalicchio and Morabito 2007;Opyrchal et al 2000;Riabov et al 2002Riabov et al , 2003Wong et al 2000], subscribers with similar interests are clustered into the same multicast group.…”

“…In general, their load sharing algorithm is only invoked upon new peers joining the system and peers are assumed to be homogeneous. Chen and Schwan [2005] proposed a dynamic overlay reconstruction algorithm called Opportunistic Overlay that reduces end-to-end delivery delay and also performs load distribution on the CPU utilization as a secondary requirement. Load balancing is triggered only when a client finds another broker that is closer than its home broker.…”

A Self-Repairing Tree Topology Enabling Content-Based Routing in Mobile Ad Hoc Networks

“…A different form of content-based publish-subscribe is proposed in [13], where the authors describe mechanisms to reconfigure an overlay network according to the changes in the physical topology and to the current brokers' load. Unlike our solution, each broker must be provided with a global view of the system.…”

Efficient Probabilistic Subsumption Checking for Content-Based Publish/Subscribe Systems

“…-The publish/subscribe systems architecture is increasingly used in environments with highly variable subscriptions, such as MANETs and sensor networks, where the assumption of both network [12] and subscription stability no longer holds.…”