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System Support for Mobile, Adaptive Applications. 2003. 4.8 Brian Noble, University of Michigan Presented by Hyeeun Choi. Contents. Introduction Application Vs. OS Fidelity Agility Stability Future Work Conclusion. Introduction. Difficulty of pervasive networking
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System Support for Mobile, Adaptive Applications 2003. 4.8 Brian Noble, University of Michigan Presented by Hyeeun Choi
Contents • Introduction • Application Vs. OS • Fidelity • Agility • Stability • Future Work • Conclusion System Support for Mobile, Adaptive Applications
Introduction • Difficulty of pervasive networking • Quality of network connectivity afforded mobile users is extremely turbulent • Mobile application must deal with such fluctuation • How can deal with such fluctuation? • Ideal • Take advantage of high–quality connectivity • Behave reasonably with poor performance • What to do • To monitor and control resource • To make adaptive decision System Support for Mobile, Adaptive Applications
Application Vs. OS • Application-Aware Adaptation • Odyssey’s approach : Collaborative Model • Policy decision to Application • Resource control to Operating System • The OS on the mobile node is wholly responsible for making adaptation decisions for applications. • Applications cannot choose to make their own adaptive decisions • Each application must inferthe resource consumption of the others. • Without a common point of resource control, cannot have accurate knowledge of one another Application-aware collaboration Application-transparent System Laissez-faire application System Support for Mobile, Adaptive Applications
Architecture of Adaptive Client • Viceroy • Manage type independent task on client • Resource usage/availability monitoring • Notifying application of changes in resource availability • Single point of resource control Figure 3. Odyssey Client Architecture • Wardens • One per type • Provide all type specific functionality • Manage communication between client & server • Offer menu of fidelity to application System Support for Mobile, Adaptive Applications
Fidelity • Measure of data quality • The degree to which a data item used by a mobile client • It is per type , not per application. • Some different dimension is possible • Related to adaptation policy • Require knowledge of item or type’s structure Figure 1. Fidelity dimensions for images System Support for Mobile, Adaptive Applications
Agility • Agility • The Limit on Adaptation • Detecting change of resource availability • Viceroy’s role • By passive observation of network • Trace network RPC latency & bulk transfer rate • Estimate available bandwidth to server & notify application • Application can adapt changed environment via adaptive decision loop System Support for Mobile, Adaptive Applications
Stability • Stability • Improving the use experience • If perceived difference between some fidelities is too large, • User can’t tolerate of frequent, perceptual large changes • Application must be skeptical of an increase in resource availability • Viceroy’s role VS Application’s role • Add information about expected variance of availability • Application can decide their own stability System Support for Mobile, Adaptive Applications
Conclusion • Collaborative adaptation model • OS : adaptation mechanism • Application : adaptation policy • Powerful model • Consideration about • Agility • Stability System Support for Mobile, Adaptive Applications
Programming model • Programming model • A decision loop • Adaptive applications are equipped to handle different fidelities • proxy Figure 4. Adaptive Decision Loop System Support for Mobile, Adaptive Applications