Opportunistic Overlays: Efficient Content Delivery in Mobile Environments

Mobile ad hoc networks;Adaptive middleware;Communication middleware;Overlay networks;Active middleware

Chen, Yuan ; Computing

University:Georgia Institute of Technology

Department:Computing

关键词: Mobile ad hoc networks;    Adaptive middleware;    Communication middleware;    Overlay networks;    Active middleware;   

Others  :  https://smartech.gatech.edu/bitstream/1853/6893/1/chen_yuan_200505_phd.pdf

美国|英语

来源: SMARTech Repository

【 摘 要 】

Middleware has become a key enabler for the development ofdistributed applications. Unfortunately, conventional middlewaretechnologies do not yet offer sufficient functionality to make themsuitable for mobile environments. This dissertation proposes a novelmiddleware approach termed opportunistic overlays and itsdynamically reconfigurable support framework for building efficientmobile applications. Specifically, we address the inefficiency ofcontent delivery introduced by node mobility and by dynamicallychanging system loads, in the context of publish/subscribe systems.In response to changes in physical network topology, in nodes'physical locations, and in network node behaviors, the opportunisticoverlay approach dynamically adapts event dissemination structures(i.e., broker overlays) with the goal of optimizing end-to-enddelays in event delivery. Adaptation techniques include the dynamicconstruction of broker overlay networks, runtime changes of mobileclients' assignments to brokers, and dynamic broker load balancing.Essentially, opportunistic overlays implement a middleware-levelanalogue of the networking routing protocols used in wirelesscommunications (i.e., Mobile IP, AODV, DSR and DSDV). By thuscoordinating network- with middleware-level routing, opportunisticoverlays can attain substantial performance improvements overnon-adaptive event systems. Such improvements are due to their useof shorter network paths and better balancing of loads across eventbrokers.Opportunistic overlays and the adaptive methods they use arerealized by a set of distributed protocols implemented in aJava-based publish/subscribe infrastructure. Comprehensiveperformance evaluations are performed via simulation, emulation, andwith two representative applications on actual networks.Experimental results demonstrate that the opportunistic overlayapproach is practically applicable and that the performanceadvantages attained from the use of opportunistic overlays can besubstantial, in both infrastructure-based mobile environments andmobile ad hoc networks.