Data Dissemination in Wireless Computing Environments

Data Dissemination in Wireless Computing Environments




In our increasingly mobile world the ability to access information on demand at any time and place can satisfy people's information needs as well as confer on them a competitive advantage. The emergence of battery-operated, low-cost and portable computers such as palmtops and PDAs, coupled with the availability and exploitation of wireless networks, have made possible the potential for ubiquitous computing. Through the wireless networks, portable equipments will become an integrated part of existing distributed computing environments, and mobile users can have access to data stored at information servers located at the static portion of the network even while they are on the move. Traditionally, information is retrieved following a request-response model. However, this model is no longer adequate in a wireless computing environment. First, the wireless channel is unreliable and the bandwidth is low compared to the wired counterpart. Second, the environment is essentially asymmetric with a large number of mobile users accessing a small number of servers.



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Published 01 January 2000
Reads 9
EAN13 0306470268
License: All rights reserved
Language English

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Preface vii 1. INTRODUCTION 1 1.1 Reference Architecture of Wireless Computing Environments 1 1.2 Characteristics of Wireless Computing Environments 3 1.3 Potential, Benefits and Applications 4 1.4 Design Issues in Wireless Data Dissemination 7 2. MODELS FOR INFORMATION DISSEMINATION 9 2.1 Taxonomy of Data Delivery Mechanisms 9 2.2 Performance Metrics 18 3. DATA BROADCAST SCHEDULING 21 3.1 Organization of Broadcast for Pushbased Broadcast System 21 3.2 Scheduling Strategies for Pullbased Broadcast System 33 4. INDEXING ON AIR 41 4.1 Data Organization for Selective Tuning 41 4.2 Flat Broadcast Programs with Indexes 44 4.3 Selective Tuning for Skewed Data Access 54 4.4 Non55flat Broadcast Programs with Indexes 4.5 Selective Tuning Mechanisms for Pull60Based Model 5. FAULTTOLERANT BROADCAST ORGANIZATION 71 5.1 Fault on Air 71 5.2 Characteristics of Fault Tolerant Index 73 5.3 InterIndex Schemes 74 5.4 Intra76Index Schemes 6. CACHE INVALIDATION MECHANISMS 87 6.1 A Taxonomy of Cache Invalidation Schemes 88 6.2 Cache Invalidation Schemes 95
7. BALANCING PUSH AND PULL 7.1 Architecture of Integrated Model 7.2 The Case for Dynamism 7.3 Adaptive Integrated Models 8. SUPPORTING RELATIONAL OPERATIONS 8.1 Cache Coherency Strategies in Pullbased Systems 8.2 Join Processing in Pushbased Systems 9. CONCLUSIONS 9.1 Summary 9.2 Research Directions References Index
115 116 116 119
 131 131 137
145 145 147 153 165