cpet 565 mobile computing systems data dissemination and management (1) lecture 7 hongli luo indiana...

CPET 565 Mobile Computing SystemsCPET 565 Mobile Computing Systems

Data Dissemination and Management (1)Data Dissemination and Management (1)

Lecture 7Lecture 7

Hongli Luo Hongli Luo Indiana University-Purdue University Fort WayneIndiana University-Purdue University Fort Wayne

Data Dissemination and Management - Data Dissemination and Management - TopicsTopics

IntroductionIntroduction ChallengesChallenges Data DisseminationData Dissemination Mobile Data CachingMobile Data Caching Mobile Cache Maintenance SchemesMobile Cache Maintenance Schemes Mobile Web CachingMobile Web Caching SummarySummary

Data Dissemination and Management – Data Dissemination and Management – Topics Topics (cont.)(cont.)

IntroductionIntroduction• Pull (On-Demand) ModePull (On-Demand) Mode• Push (Publish-Subscribe) ModePush (Publish-Subscribe) Mode• Information CachingInformation Caching

ChallengesChallenges• Architecture-basedArchitecture-based• Architecture-lessArchitecture-less

Data DisseminationData Dissemination• Bandwidth Allocation for PublishingBandwidth Allocation for Publishing• Broadcast Disk SchedulingBroadcast Disk Scheduling

Data Dissemination and Management – Data Dissemination and Management – Topics Topics (cont.)(cont.)

Mobile Data CachingMobile Data Caching• Caching in Traditional Distributed SystemsCaching in Traditional Distributed Systems• Cache Consistency MaintenanceCache Consistency Maintenance• Performance and Architecture IssuesPerformance and Architecture Issues

Mobile Cache Maintenance SchemesMobile Cache Maintenance Schemes• A Taxonomy of Cache MaintenanceA Taxonomy of Cache Maintenance• Cache Maintenance for Push-based Information DisseminationCache Maintenance for Push-based Information Dissemination• Broadcasting Invalidation ReportsBroadcasting Invalidation Reports• Disconnected OperationDisconnected Operation• Asynchronous Stateful (AS) Scheme Asynchronous Stateful (AS) Scheme • To Cache or Not to CacheTo Cache or Not to Cache

Mobile Web CachingMobile Web Caching• Handling DisconnectionsHandling Disconnections• Achieving Energy and Bandwidth Achieving Energy and Bandwidth

Data Dissemination and Management - Data Dissemination and Management - IntroductionIntroduction

Mobile Information Content and Mobile Information Content and ApplicationsApplications• Email, Messaging, NewsEmail, Messaging, News• Public Transportation, Traffic, Flight StatusPublic Transportation, Traffic, Flight Status• Business Info, Financial Info, Banking, Stock Business Info, Financial Info, Banking, Stock

quotes, Salesquotes, Sales• Events, ParkingEvents, Parking• Tourism, Hotel, Restaurants, WeatherTourism, Hotel, Restaurants, Weather• MedicalMedical• Consumer Services, Yellow pagesConsumer Services, Yellow pages

Data Dissemination and Management – Data Dissemination and Management – Introduction Introduction (cont.)(cont.)

Mobile Information ServersMobile Information Servers• EmailEmail• Web PortalWeb Portal• Calendar, Tasks, and ContactsCalendar, Tasks, and Contacts• etcetc

Possible CombinationsPossible Combinations• HardwareHardware• Network Protocols (Wireless Access Protocols, Network Protocols (Wireless Access Protocols,

GSM/Circuit, TDMA/CDPD, TDMA/Circuit)GSM/Circuit, TDMA/CDPD, TDMA/Circuit)• BrowsersBrowsers• GatewaysGateways

Data Dissemination and Management - Data Dissemination and Management - Introduction Introduction (cont.)(cont.)

Mobile Application Server Architecture Mobile Application Server Architecture (Data & Information) (Data & Information) • 11stst Tier – Thin clients Tier – Thin clients• 22ndnd Tier – Communications & Business Tier – Communications & Business

ApplicationsApplications• 33rdrd Tier – Database Systems (ERP, CRM, etc) Tier – Database Systems (ERP, CRM, etc)ReferencesReferences

http://www.mobileinfo.com/application_servers.htmhttp://www.mobileinfo.com/application_servers.htm


Wireless Communication ProblemsWireless Communication Problems• Physical MediumPhysical Medium

Signal FadingSignal Fading Path LossPath Loss InterferenceInterference Time dispersionTime dispersion

• Lower bandwidthLower bandwidth• Higher error ratesHigher error rates• Higher communication latencyHigher communication latency


Mobile Communication InfrastructuresMobile Communication Infrastructures• Wi-FiWi-Fi• Wi-MaxWi-Max• CDMA (Code Division Multiple Access)CDMA (Code Division Multiple Access)• GPRS (General Packet Radio Service; for data GPRS (General Packet Radio Service; for data

packet service on GSM network) packet service on GSM network) • EDGE (Enhanced Data GSM Evolution, up to 384 EDGE (Enhanced Data GSM Evolution, up to 384

Kbps)Kbps)• 3G (33G (3rdrd Generation Wireless Technology include Generation Wireless Technology include

enhanced multimedia, and upwards of 2 Mbps enhanced multimedia, and upwards of 2 Mbps throughput)throughput)

• Bluetooth, IrDA, IrFM, OMA (Open Mobile Alliance) Bluetooth, IrDA, IrFM, OMA (Open Mobile Alliance) Device ManagementDevice Management


Mobile Application (Data & Information) Mobile Application (Data & Information) • Enterprise Resource Planning (ERP)Enterprise Resource Planning (ERP)• Customer Resource Management (CRM)Customer Resource Management (CRM)• Sales Force AutomationSales Force Automation• Financial Accounting SystemFinancial Accounting System• Manufacturing SystemsManufacturing Systems• Field ServicesField Services

Data Dissemination and Management –Data Dissemination and Management –Introduction Introduction (cont.)(cont.)

Examples of Mobile Application ServersExamples of Mobile Application Servers• IBM Websphere Application ServerIBM Websphere Application Server• Oracle Mobile Application ServerOracle Mobile Application Server• Sybase Mobile Application StudioSybase Mobile Application Studio• Nokia WAP Application Gateway Nokia WAP Application Gateway • Microsoft Mobile Information ServerMicrosoft Mobile Information Server

http://technet.microsoft.com/en-us/library/http://technet.microsoft.com/en-us/library/bb676815.aspxbb676815.aspx


Other Related Tasks and/or ModulesOther Related Tasks and/or Modules• Mobile Data/Information IntegrationMobile Data/Information Integration• Global Mobile Information SystemGlobal Mobile Information System• Mobile Information Protection & SecurityMobile Information Protection & Security• Mobile Information CenterMobile Information Center• Unified Data ModelUnified Data Model• Middleware for Mobile Information AccessMiddleware for Mobile Information Access

Data Dissemination and Management – Data Dissemination and Management – IntroductionIntroduction (cont.)(cont.)

Mobile Information Delivery MethodsMobile Information Delivery Methods• Push (Publish-Subscribe) ModePush (Publish-Subscribe) Mode

Information broadcasting when its availableInformation broadcasting when its available Resource-efficientResource-efficient ScalableScalable

• Pull (On-Demand) ModePull (On-Demand) Mode User send query for particular information to an User send query for particular information to an

information source (server or peer)information source (server or peer) ReplyReply

• Information CachingInformation Caching Document, filesDocument, files


Issues of Mobile Information ServicesIssues of Mobile Information Services• Publication Content: Which itemsPublication Content: Which items• Publication Frequency: How oftenPublication Frequency: How often• Bandwidth Allocation:Bandwidth Allocation:

Uplink channelsUplink channels Downlink channelsDownlink channels Adaptive to usage pattern in a cellAdaptive to usage pattern in a cell

• How can mobile users access services How can mobile users access services transparently?transparently?

Broadcast channels, directory channelBroadcast channels, directory channel


How can mobile users access services transparently?How can mobile users access services transparently?

Data Server

Figure 3.1 Broadcast channel

Base-station(cell d)Base-station

(cell c)

Inde

x | S

tock

| Tr

affic

| S

ales

Mobile m’s trajectory

Data ServerIn

dex

| Eve

nts

| Par

king

| S

ales

Adapted from the Text: Fundamentals of Mobile and Pervasive Computing, 2005, by Frank Adelstein, et. al, McGraw-Hill


• How can their energy consumption be How can their energy consumption be minimized? (Energy efficient Info services) minimized? (Energy efficient Info services)

CPU in “doze mode”CPU in “doze mode” Low-power radio circuit – matching a predefined Low-power radio circuit – matching a predefined

set of packet addressset of packet address Store data in a low-energy bufferStore data in a low-energy buffer Wake-up the CPU after a certain time intervalWake-up the CPU after a certain time interval Run CPU clock in a low-power modeRun CPU clock in a low-power mode


• Publish-subscribePublish-subscribe Conserves battery power since no uplink query is Conserves battery power since no uplink query is

neededneeded More scalable – access time independent of the More scalable – access time independent of the

number of mobile hosts requesting the datanumber of mobile hosts requesting the data More useful in asymmetric environmentsMore useful in asymmetric environments


• Information cachingInformation caching Caching to avoid frequent accessCaching to avoid frequent access Replenish on an as-needed basis or in a predictive Replenish on an as-needed basis or in a predictive

mannermanner Hoarding items that are in short supply and Hoarding items that are in short supply and

become available only occasionallybecome available only occasionally How to guarantee the consistency of cached How to guarantee the consistency of cached

informationinformation

Data Dissemination and Management - Data Dissemination and Management - ChallengesChallenges

ChallengesChallenges• Architecture-basedArchitecture-based• Architecture-lessArchitecture-less

Environment ChallengesEnvironment Challenges• Intermittent PowerIntermittent Power• Intermittent ConnectivityIntermittent Connectivity• Long Travel TimesLong Travel Times• Variable Population DensityVariable Population Density• Lack of Secure StorageLack of Secure Storage

User ChallengesUser Challenges• Mobile WorkforceMobile Workforce• User Education LevelsUser Education Levels


Architecture-Based Cellular Mobile Architecture-Based Cellular Mobile NetworksNetworks

1.1. Weak ConnectivityWeak Connectivity2.2. Severe Resource ConstraintsSevere Resource Constraints3.3. Asymmetric Communication LinksAsymmetric Communication Links4.4. Location and Time (context) Dependent Location and Time (context) Dependent

Architecture-less Mobile Ad Hoc Network Architecture-less Mobile Ad Hoc Network (MANET)(MANET)

1.1. Weak ConnectivityWeak Connectivity2.2. Severe Resource ConstraintsSevere Resource Constraints


1. Architecture-Based Cellular Mobile 1. Architecture-Based Cellular Mobile Networks - Weak ConnectivityNetworks - Weak Connectivity

How to ensure high data How to ensure high data availabilityavailability in in mobile computing environment where mobile computing environment where frequent frequent disconnectionsdisconnections may occur may occur because the clients and server may be because the clients and server may be weakly connectedweakly connected??


2. Architecture-Based Cellular Mobile 2. Architecture-Based Cellular Mobile Networks - Severe Resource ConstraintsNetworks - Severe Resource Constraints

How to minimize How to minimize resource consumptionresource consumption (e.g. energy and bandwidth) for data (e.g. energy and bandwidth) for data management while ensuring a desired management while ensuring a desired level of level of data consistencydata consistency??


3. Architecture-Based Cellular Mobile 3. Architecture-Based Cellular Mobile Networks - Asymmetric Communication Networks - Asymmetric Communication LinksLinks

How can the asymmetric nature of How can the asymmetric nature of wireless connectivity be exploited to wireless connectivity be exploited to ensure low data access ensure low data access latencylatency and and resource consumptionresource consumption??


4. Architecture-Based Cellular Mobile 4. Architecture-Based Cellular Mobile Networks - Location and Time (context) Networks - Location and Time (context) Dependent Dependent

• A mobile user A mobile user ↔ Query database periodically to ↔ Query database periodically to retrieve location dependent and time-dependent retrieve location dependent and time-dependent informationinformation

• Traveler ↔ restaurants, hotelsTraveler ↔ restaurants, hotels• Salesman ↔ up-to-date product price Salesman ↔ up-to-date product price

Caching and pre-fetching can be an effective Caching and pre-fetching can be an effective technique to reduce the impact oftechnique to reduce the impact of

• Low-bandwidthLow-bandwidth• Intermittent wireless linksIntermittent wireless links


4. Architecture-Based Cellular Mobile 4. Architecture-Based Cellular Mobile Networks - Location and Time (context) Networks - Location and Time (context) Dependent Dependent

• The decision to cache or replace a data item The decision to cache or replace a data item also depends on the context (location) of the also depends on the context (location) of the mobile node in addition to the temporal or mobile node in addition to the temporal or spatial localityspatial locality

How do you enhance existing cache How do you enhance existing cache management technique for management technique for context-context-dependentdependent data? data?


Architecture-less Mobile Ad Hoc Network Architecture-less Mobile Ad Hoc Network (MANET)(MANET)

1.1. Weak ConnectivityWeak Connectivity2.2. Severe Resource ConstraintsSevere Resource Constraints

Data availability and bandwidth/energy Data availability and bandwidth/energy efficiency still need to be addressedefficiency still need to be addressed

Can the data management schemes Can the data management schemes used developed for an Cellular Mobile used developed for an Cellular Mobile Networks be used directly to solve Networks be used directly to solve problems in a MANET?problems in a MANET?


Gateways of MANET/Cellular Mobile NetworksGateways of MANET/Cellular Mobile Networks• Gateways (MANET) – unreliable mobile computing Gateways (MANET) – unreliable mobile computing

devicesdevices• Base Stations – reliable dedicated networking Base Stations – reliable dedicated networking

devicesdevices• MANETs Remote Communication LinksMANETs Remote Communication Links

Unreliable, Low Bandwidth Links: Radio Unreliable, Low Bandwidth Links: Radio Frequency Wireless LinksFrequency Wireless Links

High-latency, unreliable Links: Satellite channelsHigh-latency, unreliable Links: Satellite channels• Base Stations Remote Communication LinksBase Stations Remote Communication Links

High-speed wired networks High-speed wired networks


Network Architectures of Network Architectures of MANET/Cellular Mobile NetworksMANET/Cellular Mobile Networks

• Peer-to-peer (P2P) networks – MANETsPeer-to-peer (P2P) networks – MANETs• Client-Server – Cellular Mobile NetworksClient-Server – Cellular Mobile Networks• Data Management ApproachesData Management Approaches

Cooperative CachingCooperative Caching Caching hierarchy – backbone cachesCaching hierarchy – backbone caches Hyper Text Transfer Protocol (HTTP)Hyper Text Transfer Protocol (HTTP) Internet Caching Protocol (ICP)Internet Caching Protocol (ICP)


Internet Cache Protocol, RFC 2187Internet Cache Protocol, RFC 2187 Hypertext Transfer Protocol, Hypertext Transfer Protocol,

http://www.w3.org/Protocols/http://www.w3.org/Protocols/

cpet 565 mobile computing systems data dissemination and management (1) lecture 7 hongli luo indiana...

Documents

management introduction

management introduction

management topics cont

mobile data cachingcaching

bandwidth data dissemination

aspxdata dissemination

yellow pagesdata dissemination

data packet service