UNIX系統(tǒng)編程：通信、并發(fā)與線程（英文版）

Contents
I Fundamentals 1
1 Technology’s Impact on Programs 3
1．1 TerminologyofChange ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 4
1．2 Time andSpeed ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 5
1．3 Multiprogramming and Time Sharing ． ． ． ． ． ． ． ． ． ． ． ． ． ． 7
1．4 Concurrency at the Applications Level ． ． ． ． ． ． ． ． ． ． ． ． ． 9
1．5 Security and Fault Tolerance ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 13
1．6 Buffer Overflows for Breaking and Entering ． ． ． ． ． ． ． ． ． ． 14
1．7 UNIXStandards ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 18
1．8 AdditionalReading ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 20
2 Programs， Processes and Threads 21
2．1 How a Program Becomes a Process ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 22
2．2 Threads andThreadofExecution ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 23
2．3 Layout of a Program Image ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 24
2．4 LibraryFunctionCalls ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 26
2．5 Function Return Values and Errors ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 29
2．6 ArgumentArrays ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 31
2．7 Thread-SafeFunctions ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 38
2．8 UseofStaticVariables ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 40
2．9 StructureofStaticObjects ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 42
2．10 Process Environment ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 48
2．11 Process Termination ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 51
2．12 Exercise： An env Utility ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 54
2．13 Exercise： Message Logging ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 55
2．14 AdditionalReading ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 56
3 Processes in UNIX 59
3．1 Process Identification ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 60
3．2 ProcessState ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 61
3．3 UNIX Process Creation and fork ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 64
3．4 The wait Function ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 71
3．5 The exec Function ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 78
3．6 Background Processes and Daemons ． ． ． ． ． ． ． ． ． ． ． ． ． ． 84
3．7 Critical Sections ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 86
3．8 Exercise： Process Chains ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 87
3．9 Exercise： Process Fans ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 88
3．10 AdditionalReading ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 89
4 UNIX I/O 91
4．1 DeviceTerminology ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 92
4．2 Reading and Writing ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 92
4．3 OpeningandClosingFiles ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 102
4．4 The select Function ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 107
4．5 The pollFunction ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 116
4．6 File Representation ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 119
4．7 Filters and Redirection ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 128
4．8 FileControl ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 132
4．9 Exercise： Atomic Logging ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 135
4．10 Exercise： A cat Utility ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 141
4．11 AdditionalReading ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 143
5 Files and Directories 145
5．1 UNIXFileSystemNavigation ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 146
5．2 Directory Access ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 152
5．3 UNIX File System Implementation ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 158
5．4 Hard Links and Symbolic Links ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 162
5．5 Exercise： The which Command ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 173
5．6 Exercise： Biffing ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 174
5．7 Exercise： News biff ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 177
5．8 Exercise： Traversing Directories ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 179
5．9 AdditionalReading ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 181
6 UNIX Special Files 183
6．1 Pipes ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 184
6．2 Pipelines ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 188
6．3 FIFOs ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 192
6．4 Pipes and the Client-Server Model ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 196
6．5 TerminalControl ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 203
6．6 AudioDevice ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 214
6．7 Exercise：Audio ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 219
6．8 Exercise： Barriers ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 221
6．9 Exercise： The stty Command ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 223
6．10 Exercise： Client-Server Revisited ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 223
6．11 AdditionalReading ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 223
7 Project： The Token Ring 225
7．1 RingTopology ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 226
7．2 RingFormation ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 227
7．3 RingExploration ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 234
7．4 SimpleCommunication ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 236
7．5 MutualExclusionwithTokens ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 237
7．6 MutualExclusionbyVoting ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 238
7．7 Leader Election on an Anonymous Ring ． ． ． ． ． ． ． ． ． ． ． ． 239
7．8 TokenRingforCommunication ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 241
7．9 Pipelined Preprocessor ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 243
7．10 Parallel Ring Algorithms ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 246
7．11 FlexibleRing ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 250
7．12 AdditionalReading ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 251
II Asynchronous Events 253
8 Signals 255
8．1 BasicSignalConcepts ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 256
8．2 GeneratingSignals ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 256
8．3 Manipulating Signal Masks and Signal Sets ． ． ． ． ． ． ． ． ． ． 261
8．4 Catching and Ignoring Signals―sigaction ． ． ． ． ． ． ． ． ． 267
8．5 Waiting for Signals―pause， sigsuspend and sigwait 273
8．6 Handling Signals： Errors and Async-signal Safety ． ． ． ． ． ． ． 283
8．7 Program Control with siglongjmp and sigsetjmp ． ． ． 286
8．8 Programming with Asynchronous I/O ． ． ． ． ． ． ． ． ． ． ． ． ． 288
8．9 Exercise：DumpingStatistics ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 299
8．10 Exercise： Spooling a Slow Device ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 299
8．11 AdditionalReading ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 300
9 Times and Timers 301
9．1 POSIXTimes ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 302
9．2 SleepFunctions ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 314
9．3 POSIX：XSI IntervalTimers ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 315
9．4 Realtime Signals ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 320
9．5 POSIX：TMRIntervalTimers ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 324
9．6 Timer Drift， Overruns and Absolute Time ． ． ． ． ． ． ． ． ． ． ． 329
9．7 AdditionalReading ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 339
10 Project： Virtual Timers 341
10．1 ProjectOverview ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 342
10．2 SimpleTimers ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 344
10．3 Setting One of Five Single Timers ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 347
10．4 Using Multiple Timers ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 357
10．5 A Robust Implementation of Multiple Timers ． ． ． ． ． ． ． ． ． 363
10．6 POSIX：TMRTimer Implementation ． ． ． ． ． ． ． ． ． ． ． ． ． ． 367
10．7 mycron， a Small Cron Facility ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 367
10．8 AdditionalReading ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 368
11 Project： Cracking Shells 369
11．1 BuildingaSimpleShell ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 370
11．2 Redirection ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 374
11．3 Pipelines ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 376
11．4 Signal Handling in the Foreground ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 380
11．5 Process Groups， Sessions and Controlling Terminals ． ． ． ． ． ． 386
11．6 Background Processes in ush ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 391
11．7 JobControl ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 398
11．8 Job Control for ush ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 402
11．9 AdditionalReading ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 405
III Concurrency 407
12 POSIX Threads 409
12．1 A Motivating Problem： Monitoring File Descriptors ． ． ． ． ． ． 410
12．2 Use of Threads to Monitor Multiple File Descriptors ． ． ． ． ． ． 411
12．3 ThreadManagement ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 415
12．4 ThreadSafety ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 431
12．5 User Threads versus Kernel Threads ． ． ． ． ． ． ． ． ． ． ． ． ． ． 433
12．6 Thread Attributes ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 436
12．7 Exercise： ParallelFileCopy ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 443
12．8 AdditionalReading ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 444
13 Thread Synchronization 447
13．1 POSIX Synchronization Functions ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 448
13．2 MutexLocks ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 448
13．3 At-Most-Once and At-Least-Once-Execution ． ． ． ． ． ． ． ． ． 461
13．4 Condition Variables ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 465
13．5 Signal Handling and Threads ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 473
13．6 Readers and Writers ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 478
13．7 A strerror_r Implementation ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 483
13．8 Deadlocks and Other Pesky Problems ． ． ． ． ． ． ． ． ． ． ． ． ． 483
13．9 Exercise： Multiple Barriers ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 485
13．10 AdditionalReading ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 486
14 Critical Sections and Semaphores 487
14．1 Dealing with Critical Sections ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 488
14．2 Semaphores ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 491
14．3 POSIX：SEM Unnamed Semaphores ． ． ． ． ． ． ． ． ． ． ． ． ． ． 494
14．4 POSIX：SEM Semaphore Operations ． ． ． ． ． ． ． ． ． ． ． ． ． ． 496
14．5 POSIX：SEM Named Semaphores ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 502
14．6 Exercise： LicenseManager ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 507
14．7 AdditionalReading ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 509
15 POSIX IPC 511
15．1 POSIX：XSI Interprocess Communication ． ． ． ． ． ． ． ． ． ． ． 512
15．2 POSIX：XSI Semaphore Sets ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 514
15．3 POSIX：XSISharedMemory ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 525
15．4 POSIX：XSI Message Queues ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 535
15．5 Exercise： POSIX Unnamed Semaphores ． ． ． ． ． ． ． ． ． ． ． ． 542
15．6 Exercise： POSIX Named Semaphores ． ． ． ． ． ． ． ． ． ． ． ． ． 543
15．7 Exercise： Implementing Pipes with Shared Memory ． ． ． ． ． ． 544
15．8 Exercise： Implementing Pipes with Message Queues ． ． ． ． ． 547
15．9 AdditionalReading ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 548
16 Project： Producer Consumer Synchronization 549
16．1 The Producer-Consumer Problem ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 550
16．2 Bounded Buffer Protected by Mutex Locks ． ． ． ． ． ． ． ． ． ． ． 551
16．3 Buffer Implementation with Semaphores ． ． ． ． ． ． ． ． ． ． ． ． 555
16．4 Introduction to a Simple Producer-Consumer Problem ． ． ． ． ． 560
16．5 Bounded Buffer Implementation Using Condition Variables ． ． 564
16．6 Buffers with Done Conditions ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 565
16．7 ParallelFileCopy ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 573
16．8 ThreadedPrintServer ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 575
16．9 AdditionalReading ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 580
17 Project： The Not Too Parallel Virtual Machine 581
17．1 PVM History， Terminology， and Architecture ． ． ． ． ． ． ． ． ． 582
17．2 The Not Too Parallel Virtual Machine ． ． ． ． ． ． ． ． ． ． ． ． ． 584
17．3 NTPVMProjectOverview ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 585
17．4 I/OandTestingofDispatcher ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 591
17．5 Single Task with No Input ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 600
17．6 SequentialTasks ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 601
17．7 ConcurrentTasks ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 604
17．8 Packet Communication， Broadcast and Barriers ． ． ． ． ． ． ． ． 605
17．9 TerminationandSignals ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 605
17．10 Ordered Message Delivery ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 606
17．11 AdditionalReading ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 606
IV Communication 607
18 Connection-Oriented Communication 609
18．1 TheClient-ServerModel ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 610
18．2 CommunicationChannels ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 610
18．3 Connection-Oriented Server Strategies ． ． ． ． ． ． ． ． ． ． ． ． ． 614
18．4 Universal Internet Communication Interface (UICI) ． ． ． ． ． ． 618
18．5 UICI Implementations of Different Server Strategies ． ． ． ． ． ． 621
18．6 UICIClients ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 624
18．7 Socket ImplementationofUICI ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 629
18．8 Host Names and IP Addresses ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 641
18．9 Thread-SafeUICI ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 649
18．10 Exercise： PingServer ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 652
18．11 Exercise： Transmission of Audio ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 653
18．12 AdditionalReading ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 655
19 Project： WWWRedirection 657
19．1 TheWorldWideWeb ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 658
19．2 Uniform Resource Locators (URLs) ． ． ． ． ． ． ． ． ． ． ． ． ． ． 658
19．3 HTTPPrimer ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 660
19．4 WebCommunicationPatterns ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 665
19．5 Pass-through Monitoring of Single Connections ． ． ． ． ． ． ． ． 672
19．6 Tunnel Server Implementation ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 674
19．7 ServerDriver forTesting ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 675
19．8 HTTPHeaderParsing ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 676
19．9 SimpleProxyServer ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 679
19．10 ProxyMonitor ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 680
19．11 ProxyCache ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 683
19．12 Gateways asPortals ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 684
19．13 GatewayforLoadBalancing ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 685
19．14 Postmortem ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 686
19．15 AdditionalReading ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 690
20 Connectionless Communication and Multicast 691
20．1 Introduction to Connectionless Communication ． ． ． ． ． ． ． ． 692
20．2 Simplified Interface for Connectionless Communication ． ． ． ． 693
20．3 Simple-RequestProtocols ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 697
20．4 Request-ReplyProtocols ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 702
20．5 Request-Reply with Timeouts and Retries ． ． ． ． ． ． ． ． ． ． ． 708
20．6 Request-Reply-Acknowledge Protocols ． ． ． ． ． ． ． ． ． ． ． ． 714
20．7 ImplementationofUICIUDP ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 715
20．8 ComparisonofUDPandTCP ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 724
20．9 Multicast ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 725
20．10 Exercise：UDPPortServer ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 729
20．11 Exercise： StatelessFileServer ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 730
20．12 AdditionalReading ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 732
21 Project： Internet Radio 733
21．1 ProjectOverview ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 734
21．2 AudioDeviceSimulation ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 735
21．3 UDP Implementation with One Program and One Receiver ． ． 735
21．4 UDP Implementation with Multiple Programs and Receivers ． 746
21．5 UDP Implementation of Radio Broadcasts ． ． ． ． ． ． ． ． ． ． ． 747
21．6 Multicast Implementation of Radio Broadcasts ． ． ． ． ． ． ． ． ． 750
21．7 TCPImplementationDifferences ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 750
21．8 Receiving Streaming Audio Through a Browser ． ． ． ． ． ． ． ． 755
21．9 AdditionalReading ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 759
22 Project： Server Performance 761
22．1 ServerPerformanceCosts ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 762
22．2 ServerArchitectures ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 762
22．3 ProjectOverview ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 767
22．4 Single-ClientDriver ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 767
22．5 Multiple-Client Driver ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 771
22．6 Thread-per-request and Process-per-request Implementations ． 774
22．7 Thread-worker-pool Strategy ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 774
22．8 Thread-worker Pool with Bounded Buffer ． ． ． ． ． ． ． ． ． ． ． 775
22．9 Process-worker Pool ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 775
22．10 InfluenceofDiskI/O ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 776
22．11 PerformanceStudies ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 780
22．12 Report Writing ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 790
22．13 AdditionalReading ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． ． 792