Dynamic Search Algorithm in Unstructured Peer-to-Peer Networks

Dynamic Search Algorithm in Unstructured Peer-to-Peer Networks

Abstract:-
Designing efficient search algorithms is a key challenge in unstructured peer-to-peer networks. Flooding and random walk (RW) are two typical search algorithms. Flooding searches aggressively and covers the most nodes. However, it generates a large amount of query messages and, thus, does not scale. On the contrary, RW searches conservatively. It only generates a fixed amount of query messages at each hop but would take longer search time. We propose the dynamic search (DS) algorithm, which is a generalization of flooding and RW. DS takes advantage of various contexts under which each previous search algorithm performs well. It resembles flooding for short-term search and RW for long-term search. Moreover, DS could be further combined with knowledge-based search mechanisms to improve the search performance. We analyze the performance of DS based on some performance metrics including the success rate, search time, query hits, query messages, query efficiency, and search efficiency. Numerical results show that DS provides a good tradeoff between search performance and cost. On average, DS performs about 25 times better than flooding and 58 times better than RW in power-law graphs, and about 186 times better than flooding and 120 times better than RW in bimodal topologies. Subscribe to Complete IEEE Topics and Abstract by Email For more IEEE Topics .

Author:-Tsungnan Lin Pochiang Lin Hsinping Wang Chiahung Chen
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A Modeling Methodology for Real-Timemultimedia Operating Systems

A Modeling Methodology for Real-Timemultimedia Operating Systems

Real-time scheduling theory attempts to guarantee that a
real-time task set will always meet its deadlines. Historically,
there has existed a wide gap between real-time scheduling
theory and the reality of applying the theory to task sets
implemented via real-time operating systems (RTOSs). This
paper provides aftamwork to account for implementation
costs in real-time scheduling theory. In addition, an
engineering methodology that allows users and developers
to accurately model and evaluate RTOSs is presented. We
use this methodology to model three dinerent commercial
real-time operating systems that are being used in
multimedia applications. We show how to use the RTOS
scheduling models to evaluate the performance and design
of RTOSs. Subscribe to Complete IEEE Topics and Abstract by Email For more IEEE Topics .

Author :- Kevin A. Kettler, Daniel I. Katcher, anid Jay K. Strosnider'
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