Versatile and Remote Database Access for Pervasive Processing

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Versatile and Wireless Database Access for Pervasive Computing ... Versatile Information Appliances - consolidating individualized computing and shopper gadgets ...

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An IEEE ICDE 2000 Tutorial on Mobile and Wireless Database Access for Pervasive Computing Panos K. Chrysanthis University of Pittsburgh & Carnegie Mellon University Evaggelia Pitoura University of Ioannina

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Outline Motivating Example Issues: Mobility, Wireless Communication, Portability Adaptability and Mobile Client-Server Models Location Management Broadcast information scattering Disconnected database operations Mobile Access to the Web Mobility in Workflow Systems State of Mobile DB Industry and Research Projects Unsolved Problems

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Party on Friday Update Smart Phone's logbook with visitors names. Make a note to request sustenance from Dinner-on-Wheels. Upgrade shopping list in view of the visitors drinking inclinations. Bear in mind to swipe that last container of brew's UPS mark. The shopping rundown is dependably up and coming.

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Party on Friday AutoPC recognizes a close Supermarket that promotes deals. It gets to the shopping list and your timetable on the Smart Phone. It illuminates you the pop and lager are marked down, and reminds you. that your next arrangement is in 60 minutes. There is sufficient time in light of the most recent movement report.

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Party on Friday TGIF… Smart Phone advises you that you have to request sustenance by twelve. It downloads the Dinner-on-Wheels menu from the Web on your PC with the visitors' inclinations stamped. It sends the shopping rundown to your CO-OP's PC. Everything will be conveyed when you return home at night.

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Mobile Applications Expected to make a whole new class of Applications new monstrous markets in conjunction with the Web Mobile Information Appliances - consolidating individualized computing and customer hardware Applications: Vertical: vehicle dispatching, following, purpose of offer Horizontal: mail empowered applications, sifted data arrangement, shared figuring…

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Mobile and Wireless Computing Goal: Access Information Anywhere, Anytime, and in any capacity. False names: Mobile, Nomadic, Wireless, Pervasive, Invisible, Ubiquitous Computing. Refinement: Fixed wired system: Traditional appropriated figuring. Settled remote system: Wireless registering. Remote system: Mobile Computing. Key Issues: Wireless correspondence, Mobility, Portability .

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Wireless Communication Cellular - GSM (Europe+), TDMA & CDMA (US) FM: 1.2-9.6 Kbps; Digital: 9.6-14.4 Kbps (ISDN-like administrations) Public Packet Radio - Proprietary 19.2 Kbps (crude), 9.6 Kbps (viable) Private and Share Mobile Radio Wireless LAN - remote LAN connect (IEEE 802.11) Radio or Infrared frequencies: 1.2 Kbps-15 Mbps Paging Networks – regularly one-way correspondence low getting power utilization Satellites – wide-zone scope (GEOS, MEOS, LEOS) LEOS: 2.4 Kbps (uplink), 4.8Kbps (downlink)

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Mobile Network Architecture

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Wireless qualities Variant Connectivity Low transmission capacity and unwavering quality Frequent detachments unsurprising or sudden Asymmetric Communication Broadcast medium Monetarily costly Charges per association or per message/bundle Connectivity is feeble, discontinuous and costly

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Portable Information Devices PDAs, Personal Communicators Light, little and solid to be effortlessly conveyed imbecilic terminals [InfoPad, ParcTab projects], palmtops, wristwatch PC/Phone, walkstations will keep running on AA+/Ni-Cd/Li-Ion batteries might be diskless I/O gadgets: Mouse is out, Pen is in remote association with data organizes either infrared or PDA specific HW (for pressure/encryption)

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Portability Characteristics Battery control limitations transmit/get, circle turning, show, CPUs, memory expend control Battery lifetime will see little build require vitality productive equipment (CPUs, memory) and framework programming arranged disengagements - rest mode Power utilization versus asset usage

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Portability Characteristics Resource imperatives Mobile PCs are asset poor Reduce program measure – translate script dialects (Mobile Java?) Computation and correspondence stack can't be disseminated similarly Small screen sizes Asymmetry amongst static and versatile PCs

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Mobility Characteristics Location changes area administration - cost to find is added to correspondence Heterogeneity in administrations transfer speed limitations and fluctuation Dynamic replication of information and administrations take after clients Querying information - area based reactions Security and confirmation System setup is no more drawn out static

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What Needs to be Reexamined? Working frameworks File frameworks Data-based frameworks Communication engineering and conventions Hardware and design Real-Time, sight and sound, QoS Security Application necessities and plan PDA outline: Interfaces, Languages

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Query/Transaction Processing Concern moves from CPU time and system postponements to battery power and correspondence costs (counting taxes) Updates may appear as long-running exchanges hubs may proceed in disengaged mode require new exchange models [Chrysanthis 93, Satya 94] Move information versus move question/exchange Context (area) based inquiry reactions Consistency, independence, recuperation Approximate answers Stable stockpiling for logs, information - balance out at servers? Giving uniform access in a heterogeneous domain Design of human-PC interfaces (pen-based processing) Updated framework data : Location data, client profiles

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Recurrent Themes Handling disengagements (arranged disappointments?) storing procedures overseeing irregularities Delayed compose back and prefetch: utilize organize sit still times builds memory necessities Buffering/clumping: permits mass exchanges Partitioning and replication activated by movement Compression: increment viable BW expands battery control prerequisites Receiving needs less power than sending

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Outline Motivating Example Issues: Mobility, Wireless Communication, Portability Adaptability and Mobile Client-Server Models Location Management Broadcast information dispersal Disconnected database operations Mobile Access to the Web Mobility in Workflow Systems State of Mobile DB Industry and Research Projects Unsolved Problems

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Mobility in Db Applications Need to adjust to continually changing environment : arrange c onnectivity a vailable assets and administrations By shifting and (re)negotiating : the parcel of obligations between the versatile and static components the nature of information accessible at the versatile host Example: Fidelity (degree to which a duplicate of information m atches the reference duplicate at the server)

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Adaptability Where ought to bolster for portability and flexibility be set ? Application-Aware Laissez-Faire Application Transparent (- ) applications must be re-composed which might be extremely convoluted (- ) no point of convergence of control to determine possibly contradictory application requests or as far as possible on asset utilization (+) existing applications keep on working unaltered (- ) excessively broad, can't exploit application semantics (- ) may not be feasible (e.g., amid a long detachment)

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Adaptive Applications Need: Measurement of QoS and correspondence with application A component to screen the level and nature of data and educate applications about changes . Software engineer Interface for Application-Aware Adaptation A pplications must be deft : ready to reveive occasions in an offbeat way and respond suitably An essential issue for overseeing assets and approving any application-started ask for .

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Wireless Link Fixed Network Server Client Agent C-SA-C: Server-side Agent C-SA-C : The Client/Server-side Agent/Server Mod el Splits the cooperation between the versatile clien t and server: customer operator and specialist server diverse conventions for every part of the connection every part might be executed autonomously of the other

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Responsibilities of the Agent M essaging and queying M anipulate information preceding their transmission to the customer: perform information particular pressure clump together demands change the transmission arrange

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Role of the Agent Surrogate or intermediary of the customer Any correspondence to/from the customer experiences the specialist Offload usefulness from the customer to the specialist A pplication (benefit) particular give s a portable mindful layer to specifc administrations or applications (e.g., we b - perusing or database get to) handles all solicitations from versatile customers Filters pr ovide operators that work on conventions E .g., a MPEG-operator or a TCP-operator

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Wireless Link Fixed Network Client Agent Server Mobile Host C-CA-S: Client-side Agent C-SA-S : The Client/Client-side Agent/Server Model reserving foundation prefetchin g and accumulating different correspondence improvements

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C-I-S: Client & Server Agents Wireless Link C-I-S : Client/Intercept/Server Model Caching, prefetching and so on v arious correspondence enhancements at both finishes E.g., offbeat lined RPC r elocate calculation between the specialists Client interoperability Fixed Network Agent Client Agent Server Mobile Host

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Mobile Agents Mobile operators are moving procedures connected with a schedule dynamic code and state organization I mplement the specialists of the past structures as versatile operators, E.g., server-side specialists can relocat e amid handoff customer side specialist powerfully proceed onward and off the customer Relocatable element objects (RDO) [Rover] I mplement the correspondence utilizing versatile specialists: customers submit/get portable specialists to/from the server E.g., Compacts [Pro-Motion]

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A Taxonomy

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Outline Motivating Example Issues: Mobility, Wir