Table Of ContentP1:OTE/SPH P2:OTE
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Alfred Wai-Sing Loo
Peer-to-Peer
Computing
Building Supercomputers with Web
Technologies
iii
P1:OTE/SPH P2:OTE
SVNY285-Loo October25,2006 20:48
AlfredWai-SingLoo,BSc,MSc,PhD,MBCS,MIMA,CEng,CSci,CMath,CITP
DepartmentofComputingandDecisionSciences,LingnanUniversity,
TuenMun,HongKong
SeriesEditor
ProfessorA.J.Sammes,BSc,MPhil,PhD,FBCS,CEng.
CISMGroup,CranfieldUniversity,RMCS,Shrivenham,SwindonSN68LA,
UK
BritishLibraryCataloguinginPublicationData
AcataloguerecordforthisbookisavailablefromtheBritishLibrary
LibraryofCongressControlNumber:2006925862
ComputerCommunicationsandNetworksISSN1617-7975
ISBN-10:1-84628-381-7 Printedonacid-freepaper
ISBN-13:978-1-84628-381-9
©AlfredWai-SingLoo2007
Apartfromanyfairdealingforthepurposesofresearchorprivatestudy,orcriticismorreview,as
permittedundertheCopyright,DesignsandPatentsAct1988,thispublicationmayonlybereproduced,
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Tomywife,Rebecca,forherloveandsupport
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Contents
1 OverviewofPeer-to-PeerSystem.............................................. 1
1.1 Introduction..................................................................... 1
1.2 BatchModes.................................................................... 1
1.3 On-LineModes................................................................. 3
1.4 Client-Server.................................................................... 5
1.5 Peer-to-PeerSystems.......................................................... 6
2 File-SharingPeer-to-PeerSystem.............................................. 9
2.1 Introduction..................................................................... 9
2.2 FamousNapsterModel....................................................... 9
2.3 Gnutella.......................................................................... 10
2.4 BitTorrent........................................................................ 13
2.5 CommonFeatures.............................................................. 17
2.6 LegalChallenges............................................................... 17
3 TheNeedforMorePowerfulComputers.................................... 18
3.1 Introduction..................................................................... 18
3.2 ProblemsofParallelComputers............................................. 19
3.3 CPUPowerSharingExamples.............................................. 20
3.4 NeedforParallelAlgorithms................................................ 22
3.5 MetricsinParallelSystems.................................................. 23
3.6 Summary......................................................................... 27
4 ProblemsandSolutions........................................................... 28
4.1 Problems......................................................................... 28
4.2 DesirableCharacteristicsofP2PSystems................................. 29
4.3 EnablingTechnologies........................................................ 30
4.4 OverviewofOurSolution.................................................... 31
4.5 Comparison..................................................................... 32
4.6 Impact............................................................................ 33
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viii Contents
5 WebServerandRelatedTechnologies...................................... 34
5.1 Introduction................................................................. 34
5.2 WebServers................................................................ 34
5.3 ApacheTomcat............................................................ 35
5.4 StartingtheTomcatServer............................................... 40
5.5 BetterDevelopmentEnvironment...................................... 43
5.6 Directories.................................................................. 46
5.7 MappingBetweenURLandServlet................................... 50
5.8 SelectionofWebServers................................................ 53
6 IntroductiontoServlets......................................................... 56
6.1 Introduction................................................................. 56
6.2 Servlets...................................................................... 56
6.3 ServletLifecycle........................................................... 57
6.4 ServletCollaboration..................................................... 58
6.5 BasicStructureofServlet................................................ 59
6.6 SendingandReceivingInformation................................... 60
6.7 TestingyourFirstServlet................................................ 62
6.8 TestingSecondServlet(WithouthtmlFile).......................... 64
6.9 FurtherTests................................................................ 66
6.10 CompilingtheServlet.................................................... 66
7 JavaNetworkProgramming................................................... 67
7.1 Introduction................................................................. 67
7.2 URLConnection........................................................... 67
7.3 SocketCommunication................................................... 69
7.4 Datagram.................................................................... 79
7.5 Differences................................................................. 90
8 TestingandEnhancementsofServlets...................................... 91
8.1 Introduction................................................................. 91
8.2 DebuggingTechniques................................................... 91
8.3 GlobalParameters......................................................... 95
8.4 Synchronization........................................................... 101
8.5 TipstoSpeedupTesting................................................. 103
8.6 Troubleshooting........................................................... 104
9 PowerServer:Model1.......................................................... 106
9.1 Introduction................................................................. 106
9.2 ModelWithoutWebServer—Model1................................ 107
9.3 FirstTest.................................................................... 130
9.4 SecondTest................................................................. 131
9.5 Troubleshooting........................................................... 132
9.6 FurtherTests................................................................ 133
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Contents ix
10 PowerServer:Model2.......................................................... 134
10.1 Introduction................................................................. 134
10.2 PowerServerwithWebServer—Model2............................ 135
10.3 ServerSidePrograms..................................................... 139
10.4 Phase1Testing—invokeServerProgram............................. 141
10.5 Phase2Testing............................................................ 143
11 PowerServer:Model3.......................................................... 147
11.1 Introduction................................................................. 147
11.2 PowerServer—Model3.................................................. 147
11.3 ServerProgramofModel3.............................................. 148
11.4 ClientProgramofModel3.............................................. 151
11.5 divide.javaModule........................................................ 158
11.6 share2.java.................................................................. 158
11.7 Testing....................................................................... 158
11.8 ComparisonwithModel1............................................... 163
12 PowerServer:Model4.......................................................... 165
12.1 Introduction................................................................. 165
12.2 PowerServerwithWebServer—Model4............................ 165
12.3 ServerSideProgram...................................................... 166
12.4 TestingtheinvokeServer2Program.................................... 169
12.5 TestingtheSystem........................................................ 172
13 PowerServer:Model5.......................................................... 175
13.1 Introduction................................................................. 175
13.2 PowerServer—Model5.................................................. 175
13.3 ServerSideProgram...................................................... 176
13.4 ClientSideProgram...................................................... 176
13.5 Testing....................................................................... 182
13.6 ComparisonwithModel4............................................... 186
13.7 FurtherTests................................................................ 187
13.8 OtherImprovements...................................................... 187
14 WirelessP2PSystem............................................................. 188
14.1 Introduction................................................................. 188
14.2 IEEE802Standards....................................................... 189
14.3 Bluetooth.................................................................... 189
14.4 WirelessLAN.............................................................. 190
14.5 WirelessRouters........................................................... 190
14.6 Internet-EnabledDevices................................................ 190
14.7 ProblemsofMobilePhones............................................. 191
14.8 ExtendingthePowerofMobilePhones............................... 192
14.9 WirelessP2PSystemswithMobilePhones.......................... 193
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x Contents
15 ImplementationofWirelessP2PSystems.................................. 196
15.1 Introduction................................................................. 196
15.2 Client—MobilePhone.................................................... 196
15.3 Tier1ServerProgram—phoneServlet.java........................... 196
15.4 Tier-2ServerSideProgram.............................................. 201
15.5 ToolsforMobilePhoneDevelopment................................. 201
15.6 TestingtheWirelessP2P................................................. 201
15.7 ExperimentswithMoreSub-tasks..................................... 204
15.8 Conclusions................................................................. 207
16 ComputerArchitecture......................................................... 209
16.1 Introduction................................................................. 209
16.2 ClassificationofComputerArchitectures............................. 209
16.3 Granularity.................................................................. 213
16.4 GeneralorSpeciallyDesignedProcessors............................ 215
16.5 ProcessorNetworks....................................................... 215
16.6 SharedMemoryConnection............................................. 224
16.7 Summary.................................................................... 224
17 DistributedandParallelAlgorithms........................................ 227
17.1 Introduction................................................................. 227
17.2 OverviewofSerialSorting.............................................. 228
17.3 CharacteristicsofSortingAlgorithms................................. 234
17.4 ParallelSortingAlgorithmsforMIMDwith
SharedMemory............................................................ 234
17.5 ParallelSortingAlgorithmsforMIMDwith
DistributedMemory...................................................... 238
17.6 Conclusions................................................................. 238
18 InfrastructureandFutureDevelopment................................... 240
18.1 Infrastructure............................................................... 240
18.2 Incentives................................................................... 241
18.3 Maintenance................................................................ 242
18.4 FutureP2PDevelopment................................................ 244
18.5 ProblemsofData-SharingP2PSystem................................ 245
18.6 EfficientParallelAlgorithms............................................ 246
18.7 Re-VisitingSpeedUp..................................................... 246
18.8 Applications................................................................ 247
18.9 FurtherImprovements.................................................... 247
AppendixA:Data-SharingP2PAlgorithm.................................... 248
AppendixB:UsefullWebsites...................................................... 260
Bibliography............................................................................ 262
Index..................................................................................... 267
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1
Overview of Peer-to-Peer System
1.1 Introduction
Peer-to-peer(P2P)computingisthesharingofresourcesbetweencomputers.Such
resourcesincludeprocessingpower,knowledge,diskstorageandinformationfrom
distributeddatabases(Kamath,2001).Inthelastseveralyears,abouthalfabillion
dollarshavebeeninvestedincompaniesdevelopingP2Psystems.
Thiskindofinterestisduetothesuccessofseveralhigh-profileandwell-known
P2PapplicationssuchastheNapsterandOxfordanti-cancerprojects(Loo,2003).
Theconceptofsharingresourcesisnotcompletelynew.Indeed,P2Psystemsare
anaturalevolutioninsystemarchitecture.Itisworthwhiletohaveabrieflookat
thisevolution.
1.2 Batch Modes
Mainframecomputerswereimportanttoolsforlargeenterprises.Intheolddays,
therewasonlyonecomputerinoneorganizationasthemachineswereprohibitively
expensive. They required special rooms with air-conditioning. The operation of
thesecomputers(Fig.1.1)isdescribednext.
End users used to write down input data on special forms. These forms were
passed to the data entry section periodically (e.g., once a day or once a month
dependingonthenatureoftheprocess).Dataentryoperatorstypedthedatawith
specialmachines,whichconvertedthedataintopunchcard,magnetictapeand/or
magneticdisk.Suchinputmediumswerepassedtocomputerroom.Acomputer
operator then fed the data into computer. The computer processed the data and
printed the reports. Such reports were sent back to the users together with their
inputforms.
Obviously, this ‘batch processing’ mode of operation suffers from several
problems:
1. Inputdataformsarecollectedperiodicallyasabatch.Itisnotuncommonthat
users need to wait for a few days to get their computer reports. Such kinds of
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2 1.OverviewofPeer-to-PeerSystem
User department IT department
I-O control Data entry Computer
End user
staff operator operator
1. Write down
input data
Input Input
documents documents
2. Send input
3. Check input 4. Type
documents to
documents and verify
IT department
+
Input
documents 5. Return input
documents
6. Check to control staff
input medium (with input
medium)
7. Send input 8. Record and
medium arrange schedule
Computer
reports
10. Check 9. Feed input
completeness to computer
Computer
printouts
Input
document
12. Check
11. Send input
correctness
documents
of printouts
and computer
printouts
Figure1.1. Operationofbatchsystem.
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On-LineModes 3
delays are acceptable for systems such as payroll as they are done periodically.
However,itisnotsatisfactoryforsystemsthatneedimmediateanswers,suchas
aninventorycontrolsystem.
2. End users collect the data and write them down on input forms. Data entry
operators do the typing. As the data entry operators do not have the knowledge
of the applications, it is easier to make typing mistakes. It is more difficult for
them to detect problems. A ‘verifying’ process is commonly used to overcome
thisproblem.Theideaissimplebutthecostisheavy.Theinputdataaretypedby
oneoperator.Thenanotheroperatortypesitagain.Thesystemcomparesthefirst
typingwiththesecondtyping.Anydiscrepancydetectedwillbereportedsothe
dataentryoperatorcanchecktheproblem.Thisprocessiseffectiveindetecting
typingerrorsbutisexpensiveasweneedtotypetwiceforallcriticalsystems.It
isalsotimeconsumingandcausesdelaysinfurtherprocessing.
1.3 On-Line Modes
Since hardware costs decreased and technology advanced, the ‘on-line process-
ing’modebecameavailabletoenterprises.Terminalscouldbeconnectedtomain-
frame computers (Fig. 1.2). The first-generation terminal consisted of only two
Data
Mainframe
st
Reque ponse
1. es
R
2.
Monitor Monitor Monitor
Monitor
3. Display information
Keyboard Keyboard Keyboard
Keyboard
Figure1.2. Mainframewithdumbterminals.
