网络互连技术系列 下载 pdf 百度网盘 epub 免费 2025 电子书 mobi 在线

内容简介

TCP/IP网络互连技术系列的第Ⅲ卷讨论客户/服

务器编程和应用.讲述了构筑所有分布式计算系统的客

户/服务器计算模型的基本概念，内容包括各种不同的

服务器设计方法，以及用来构造客户/服务器的各种工具

和技术，包括远程调用RPC。书中包括了用来说明每种

设计和工具的运行程序示例的源代码。

第Ⅲ卷有三个版本：分别对应于广为应用的BSD

套接字，AT&TTLI接口和WindowsSockets。本书

是BSD套接字版，在所有编程实例中使用BSDUNIX

套接字机制。

Contents

Foreword xxiii

Preface xxv

Chapter 1 Introduction And Overview

1.1 UseOfTCP/IP

1.2 Designing Applications For A Distributed Environment

1.3 Standard And Nonstandard Application Protocols

1.4 An Example Of Standard Application Protocol Use

1.5 An Example Connection

1.6 Using TELNET To Access An Altemative Service

1.7 Application Protocols And Software Flexibility

1.8 Viewing Services From The Provider's Perspective

1.9 The Remainder OfThis Texl

1.10 Summary

Chapter 2 The Client Server Model And Software Design

2.1 Introduction

2.2 Motivation

2.3 Terminology And Concepts

2.3.1 Clients And Servers

2.3.2 Privilege And Complexity

2.3.3 Standard Vs. Nonstandard Client Software

2.3.4 Parameteriz.ation Of Clients

2.3.5 Connectionless Vs. Connection-Oriented Servers

2.3.6 Stateless Vs. Stateful Servers

2.3.7 A Stateful File Server Example

2.3.8 Statelessness Is A Prolocol Issue

2.3.9 Servers As Clients

2.4 Summary

Chapter 3 Concurrent Processing In Cllent-Server Software

3.1 Inlroduction

3.2 Concurrency In Networks

3.3 Concurrency In Servers

3.4 Terminology And Concepts

3.4.1 The Process Concept

3.4.2 Programs vs. Processes

3.4.3 Procedure Calls

3.5 An Example OfConcurrent Process Creation

3.5.1 A Sequential C Example

3.5.2 A Concurrent Version

3.5.3 Timeslicing

3.5.4 Making Processes Diverge

3.6 Executing New Code

3.7 ContextSwitching And Protowl Software Design

3.8 Concurrency And Asynchronous 1/0

3.9 Summary

Chapter 4 Program Interface To Protocols

4.1 Introduction

4.2 Loosely Specified Protocol Software Interface

4.2.1 Advantages And Disadvantages

4.3 Interface Functionality

4.4 Conceptual Interface Specification

4.5 System Calls

4.6 Two Basic Approaches To Network Communication

4.7 The Basic 1/0 Functions Available In UNIX

4.8 Using UNIX 1/0 With TCP/IP

4.9 Summary

Chapter 5 The Socket Interface

5.1 Introduction

5.2 Berkeley Sockets

5.3 Specifying A Protocol Interface

5.4 The Socket Abstraction

5.4.1 Socket Descriptors And File Descriptors

5.4.2 System Data Structures For Sockets

5.4.3 Using Sockets

5.5 Specifying An Endpoint Address

5.6 A Generic Address Structure

5.7 Major System Calis Used With Sockets

5.7.1 The Socket Call

5.7.2 The Connect Call

5.7.3 TheWriteCall

5.7.4 TheReadCall

5.7.5 TheCloseCall

5.7.6 TheBindCall

5.7.7 The Listen Call

5.7.8 The Accept Call

5.7.9 Summary OfSockel Calls Used With TCP

5.8 Utilily Routines For Integer Conversion

5.9 Vsing Socket Calls In A Program

5.10 Symbolic Constants For Socket Call Parameters

5.11 Summarv

Chapter 6 Algorithms And Issues In Client Software Deslgn

6.1 Introduction

6.2 Leaming Algorithms Instead Of Details

6.3 Client Architecture .

6.4 Idenlifying The Localion OfA Server

6.5 Parsing An Address Argument

6.6 Looking Up A Domain Name

6.7 Looking Up A Well-Known Port By Name

6.8 Port Numbers And Network Byle Order

6.9 Looking Up A Protocol By Name

6.10 The TCP Clienl Algorithm

6.11 Allocating A Socket

6.12 Choosing A Local Protocol Port Number

6.13 A Fundamental Problem In Choosing A Local IP Address

6.14 Connecling A TCP Socket To A Server

6.15 Communicating With The Server Using TCP

6.16 Reading A Response From A TCP Connection

6.17 Closing A TCP Connection

6.17.1 The Need For Partial Close

6.17.2 A Partial Close Operation

6.18 Programming A UDP Client

Chapter 7 Example Client Software

7.1 Introduction

7.2 The Importance OfSmall Examples

7.3 Hiding Details

7.4 An Example Procedure Library For Client Programs

7.5 Implementation Of ConnectTCP

7.6 Implementation OfConnectUDP

7.7 A Procedure That Forms Connections

7.8 Using The Example Library

7.9 The DA YTIME Service

7.10 Implemenlation OfA TCP Client For DAYTIME

7.11 Reading From A TCP Connection

7.12 The TIME Service

7.13 Accessing The TIME Service

7.14 Accurate Times And Network Delays

7.15 A UDP Clienl For The TIME Service

7.16 The ECHO Service

7.17 A TCP Client For The ECHO Service

7.18 A UDP Client For The ECHO Service

7.19 Summary

Chapter 8 Algorithms And Issues In Server Software Design

8.l Introduction

8.2 The Conceptual Server Algorithm

8.3 Concurrent Vs. Iterative Servers

8.4 Connection-Oriented Vs. Connectionless Access

8.5 Connection-Oriented Servers

8.6 Connectionless Servers

8.7 Failure, Reliability, And Statelessness

8.8 Optimizing Stateless Servers

8.9 Four Basic Types Of Servers

8.10 Request Processing Time

8.11 llerative Server Algorithms 102

8.12 An Iteralive, Connecfion-Oriented Server Algorithm

8.13 Binding To A Well-Known Address Using INADDR.ANY

8.14 Placing The Socket In Passive Mode

8.15 Accepting Connections And Using Them

8.16 An Iterative, Connectionless Server Algorithm

8.17 Fonning A Reply Address In A Connectionless Server

8.18 Concurrent Server Algorithms

8.19 Masler And Slave Processes

8.20 A Concurrent, Connectionless Server Algorithm

8.21 A Concurrent, Connection-Oriented Server Algorithm

8.22 Using Separate Programs As Slaves

8.23 Apparent Concurrency Using A Single Process

8.24 When To Use Each Server Type

8.25 A Summary ofServer Types

8.26 The Important Problem Qf Server Deadlock

8.27 Alternative Implementations

8.28 Summary

Chapter 9 Iterative, Connectionless Servers (UDP)

9.1 lntroduction

9.2 Creating A Passive Socket

9.3 Process Structure

9.4 An Example TIME Server

9.5 Summary

Chapter 10 Iterative, Connection-Orlented Servers (TCP)

10.1 Inlroduction

10.2 Allocating A Passive TCP Socket

10.3 A Server For The DA YTIME Service

10.4 Process Structure

10.5 An Example DA YTIME Server

10.6 Closing Connections

10.7 Conneclion Termination And Server Vulnerability

10.8 Summary

Chapter 11 Concurrent, Connection-Oriented Servers (TCP)

11.1 Introduction

11.2 Concurrent ECHO

11.3 Iterative Vs. Concurrent Implementations

11.4 Process Structure

11.5 An Example Concurrent ECHO Server

11.6 Cleaning Up Errant Processes

11.7 Summary

Chapter 12 Single-Process, Concurrent Servers (TCP)

12.1 Inlroduction

12.2 Data-driven Processing In A Server

12.3 Data-Driven Processing With A Single Process

12.4 Process Structure OfA Single-Process Server

12.5 An Example Single-Process ECHO Server

12.6 Summary

Chapter 13 Multiprotocol Servers (TCP, UOP)

13.1 Introduction

13.2 The Motivation For Reducing The Number Of Servers

13.3 Multiprotocol Server Design

13.4 Process Structure

13.5 An Example Multiprotocol DA YTIME Server

13.6 The Concept OfShared Code

13.7 Concurrent Multiprotocol Servers

13.8 Summary

Chapter 14 Multiservice Servers (TCP, UDP)

14.1 Introduction

14.2 Consolidating Servers

14.3 A Connectionless, Multiservice Server Design

14.4 A Connection-Oriented, Multiservice Server Design

14.5 A Concurrent, Connection-Oriented, Multiservice Server

14.6 A Single-Process, Multiservice Server Implementation

14.7 Invoking Separate Programs From A Multiservice Server

14.8 Multiservice, Multiprotocol Designs

14.9 An Example Multiservice Server

14.10 Static and Dynamic Server Configuration

14.11 The UNIX Super Server. Inetd

14.12 An Example Inetd Server

14.13 Summary

Chapter 15 Uniform, Efficient Management Of Server Concurrency

15.1 Introduction

15.2 Choosing Between An Iterative And A Concurrent Design

15.3 Level Of Concurrency

15.4 Demand-Driven Concurrency

15.5 The Cost Of Concurrency

15.6 Overhead And Delay

15.7 Small Delays Can Matter

15.8 Process Preallocation

15.8.1 Preallocation In UNIX

15.8.2 Preallocation In A Connection-Oriented Server

15.8.3 Preallocation In A Connectionless Server

15.8.4 Preallocation, Bursty Trqfflc, And NFS

15.8.5 Process Preallocation On A Multiprocessor

15.9 Delayed Process Allocation

15.10 The Uniform Basis For Both Techniques

15.11 Combining Techniques

15.12 Summary

Chapter 16 Concurrency In Clients

16.1 Introduction

16.2 The Advantages Of Concurrency

16.3 The Motivation For Exercising Control

16.4 Concurrent Contact With Multiple Servers

16.5 Implementing Concurrent Clients

16.6 Single-Process Implementations

16.7 An Example Concurrent Client That Uses ECHO

16.8 Execution OfThe Concurrent Client

16.9 Concurrency In The Example Code

16.10 Summary

Chapter 17 Tunnellng At The Transport And Appllcation Levels

17.1 Introduction

17.2 Multiprotocol Environments

17.3 Mixing Network Technologies

17.4 Dynamic Circuit Allocation

17.5 Encapsulalion And Tunneling

17.6 Tunneling Through An IP Inlemet

17.7 Application-Level Tunneling Between Clients And Servers

17.8 Tunneling, Encapsulation, And Dialup Phone Lines

17.9 Summary

Chapter 18 Appllcation Level Gateways

18.1 Introduction

18.2 Clients And Servers In Constrained Environments

18.2.1 The Reality OfMultiple Technologies

18.2.2 Computers With Limited Functionality

18.2.3 Connectivity Constraints That Arise From Security

18.3 Using Applicatim Gateways

18.4 lnteroperability Through A Mail Gateway

18.5 Implementation OfA Mail Gateway

18.6 A Comparison Of Application Gateways And Tunneling

18.7 Application Gateways And Limited Functionality Systems

18.8 Application Gateways Used For Security

18.9 Application Gateways And The Extra Hop Problem

18.10 An Example Application Gateway

18.11 Implementation OfAn Application Gateway

18.12 Code For The Application Gateway

18.13 An Example Gateway Exchange

18.14 Using Rfcd With UMX's .forward

18.15 A General-Purpose Application Gateway

18.16 Operation OfSURP

18.17 How SURP Handles Connections

18.18 IP Addressing And SLIRP

18.19 Summary

Chapter 19 External Data Representation (XDR)

19.1 Introduction

19.2 Representations For Data In Computers

19.3 The N-Squared Conversion Problem

19.4 Network Standard Byte Order

19.5 A De Facto Standard External Data Representation

19.6 XDR Data Types

19.7 Implicit Types

19.8 Software Support For Using XDR

19.9 XDR Library Routines

19.10 Building A Message One Piece At A Time

19.11 Conversion Routines In The XDR Library

19.12 XDR Streams, 1/0, and TCP

19.13 Records, Record Boundaries, And Datagram 1/0

19.14 Summary

Chapter 20 Remote Procedure Call Concept (RPC)

20.1 lntroduction

20.2 Remote Procedure Call Model

20.3 Two Paradigms For Building Distributed Programs

20.4 A Conceptual Model For Conventional Procedure Calls

20.5 An Extension Of the Procedural Model

20.6 Execulion Of Conventional Procedure Call And Retum

20.7 The Procedural Model In Distributed Systems

20.8 Analogy Between Client-Server And RPC

20.9 Distributed Computation As A Program

20.10 Sun Microsystems' Remote Procedure Cail Definition

20.11 Remote Programs And Procedures

20.12 Reducing The Number Of Arguments

20.13 Identifying Remote Programs And Procedures

20.14 Accommodating Multiple Versions OfA Remote Program

20.15 Mutual Exclusion For Procedures In A Remote Program

20.16 Communicatwn Semantics

20.17 At Least Once Semantics

20.18 RPC Retransmission

20.19 Mapping A Remote Program To A Protocol Port

20.20 Dynamic Port Mapping

20.21 RPC Port Mapper A Igorithm

20.22 ONC RPC Message Format

20.23 Marshaling Arguments For A Remote Procedure

20.24 Authenlication

20.25 An Example Of RPC Message Representation

20.26 An Example OfThe UNIX Authentication Field

20.27 Summary

Chapter 21 Dlstributed Program Generation (Rpcgen Concept)

21.1 Introduction

21.2 Using Remote Procedure Calls

21.3 Programming Mechanisms To Support RPC

21.4 Dividing A Program Into Local And Remote Procedures

21.5 Adding Code For RPC

21.6 Stub Procedures

21.7 Multiple Remote Procedures And Dispatching

21.8 Name Of The Client-Side Stub Procedure

21.9 Using Rpcgen To Generate Dislribuled Programs

21.10 Rpcgen Output And Interface Procedures

21.11 Rpcgen Input And Output

21.12 Using Rpcgen To Build A Client And Server

21.13 Summary

Chapter 22 Distrlbuted Program Generation (Rpcgen Example)

22.1 Introduclion

22.2 An Example To lllustrate Rpcgen

22.3 Dictionary Look Up

22.4 Eight Steps To A Distributed Application

22.5 Step 1: Build A Conventional Application Program

22.6 Step 2: Divide The Program Into Two Parts

22.7 Step 3: Create An Rpcgen Specification

22.8 Step 4: Run Rpcgen

22.9 The h File Produced By Rpcgen

22.10 The XDR Conversion File Produced By Rpcgen

22.11 The Client Code Produced By Rpcgen

22.12 The Server Code Produced By Rpcgen

22.13 Step 5: Wrile Stub Interface Procedures

22.13.1 Client-Side Interface Routines

22.13.2 Server-Side Interface Roulines

22.14 Step 6: Compile And Link The Client Program

22.15 Step 7: Compile And Link The Server Program

22.16 Step 8: Starl The Server And Execute The Client

22.17 Using The UNIX Make Utility

22.18 Summary

Chapter 23 Network File System Concepts (NFS)

23.1 Introduction

23.2 Remote File Access Vs. Transfer

23.3 Operations On Remole Files

23.4 Fite Access Among Heterogeneous Computers

23.5 Stateless Servers

23.6 NFS And UNIX File Semantics

23.7 Review Of The UNIX File System

23.7.1 Basic Definitions

23.7.2 A Byte Sequence Withoul Record Boundaries

23.7.3 A File 's Owner And Group Identiflers

23.7.4 Protection And Access

23.7.5 The Open-Read- Write-Close Paradigm

23.7.6 Data Transfer

23.7.7 Permission To Search A Directory

23.7.8 Random Access

23.7.9 Seeking Beyond The End Of File

23.7.10 File Position And Concurrent Access

23.7.11 Semantics Of Write During Concurrent Access

23.7.12 File Names And Paths

23.7.13 Inode: Information Stored Wilh A File

23.7.14 Stat Operation

23.7.15 The File Naming Mechanism

23.7.16 File System Mounts

23.7.17 UNIX File Name Resoluuon

23.7.18 Symbolic Unks

23.8 Files Under NFS

23.9 NFS File Types

23.10 NFSFileModes

23.11 NFS File Attributes

23.12 NFS Client And Server

23.13 NFS Client Operation

23.14 NFS Client And UNIX

23.15 NFSMounts

23.16 FileHandle

23.17 Handles Replace Path Names

23.18 An NFS Client In UNIX

23.19 File Position'mg Wilh A Stateless Server

23.20 Operations On Directories

23.21 Reading A Directory Statelessly

23.22 Multiple Hierarchies In An NFS Server

23.23 The Mount Protocol

23.24 Summary

Chapter 24 Network File System Protocol (NFS, Mount)

24.l Introduction

24.2 Using RPC To Define A Protocol

24.3 Defining A Protocol With Data Structures And Procedures

24.4 NFS Constant, Type, And Data Declarations

24.4.1 NFS Constants

24.4.2 NFS Typedef Declarations

24.4.3 NFS Data Structures

24.5 NFS Procedures

24.6 Semantics OfNFS Operations

24.6.1 NFSPROC_NULL (Procedure 0)

24.6.2 NFSPROC_GETATTR (Procedure 1)

24.6.3 NFSPROC_SETATTR (Procedure 2)

24.6.4 NFSPROC_ROOT (Procedure 3) [Obsolete in NFS3]

24.6.5 NFSPROC_LOOKUP (Procedure 4)

24.6.6 NFSPROC_READLlNK (Procedure 5)

24.6.7 NFSPROC_READ (Procedure 6)

24.6.8 NFSPROC_WRITECACHE (Procedure 7) [Obsolete in NF83]

24.6.9 NFSPROC_WRITE (Procedure 8)

24.6.10 NFSPROC_CREATE (Procedure 9)

24.6.11 NFSPROC_REMOVE _(Procedure 10)

24.6.12 NFSPROCRENAME _ RENAME (Procedure 11)

24.6.13 NFSPROC_LINK (Procedure 12)

24.6.14 NFSPROC_SYMUNK (Procedure 13)

24.6.15 NFSPROC_MKDlR (Procedure 14)

24.6.16 NFSPROC_RMDlR (Procedure 15)

24.6.17 NFSPROC_READDIR (Procedure 16)

24.6.18 NFSPROC_STATFS (Procedure 17)

24.7 The Mount Protocol

24.7.1 Mount Constant Definitions

24.7.2 Mounl Type Definitions

24.7.3 Mount Data Slructures

24.8 Procedures In The Mount Protocol

24.9 Semantics of Mount Operations

24.9.1 MNTPROC_NULL (Procedure 0)

24.9.2 MNTPROC_MNT (Procedure 1)

24.9.3 MNTPROC_DUMP (Procedure 2)

24.9.4 MNTPROC_UMNT (Procedure 3)

24.9.5 MNTPROC_UMNTALL (Procedure 4)

24.9.6 MNTPROC_EXPORT (Procedure 5)

24.10 NFS And Mount Authenlication

24.11 Changes In NFS Version 3

24.12 Summary

Chapter 25 A TELNET Client (Program Structure)

25.1 Introduclion

25.2 Overview

25.2.1 The User's Terminal

25.2.2 Command And Control Information

25.2.3 Terminals, Windows, and Files

25.2.4 The Need For Concurrency

25.2.5 A Process Model For A TEENET Ctient

25.3 A TELNET Client Algorithm

25.4 Terminal 1/0 In UNIX

25.4.1 Conlrolting A Device Oriver

25.5 Establishing Terminal Modes

25.6 Global Variable Used For Slored Stale

25.7 Restoring Terminal Modes Before Exil

25.8 Client Suspension And Resumption

25.9 Finite State Machine Specification

25.10 Embedding Commands In A TELNET Data Stream

25.11 Option Negoliation

25.12 Request/Offer Symmetry

25.13 TELNET Character Definitions

25.14 A Finite State Machine For Data From The Server

25.15 Transitions Among States

25.16 A Finite State Machine Implementalion

25.17 A Compacl FSM Represenlalion

25.18 Keeping The Compact Representation At Run-Time

25.19 Implementation OfA Compact Representation

25.20 Building An FSM Transition Matrix

25.21 The Socket Output Finite Stale Machine

25.22 Definitions For The Socket Output FSM

25.23 The Option Subnegotialion Finite State Machine

25.24 Definilions For The Option Subnegotiation FSM

25.25 FSM Initializatwn 393

25.26 Argumenfs For The TELNET Client

25.27 TheHeartOfTheTELNETClient

25.28 Imptementation Of The Main FSM

25.29 Summar)

Chapter 26 A TELNET Client (Implementation Oetails)

26.1 Introduclion

26.2 The FSM Action Procedures

26.3 Recording The Type OfAn Option Request

26.4 Performing No Operation

26.5 Responding To WILI/WONT For The Echo Option

26.6 Responding To WILL/WONT For Unsupported Options

26.7 Responding To WILL/WONT For The No Go-Ahead Option

26.8 Generating DO/DONT For Binary Transmission

26.9 Responding To DO/DONT For Unsupported Options

26.10 Responding To DO/DONT For Transmit Binary Option

26.11 Responding To DOfDONT For The Terminal Type Option

26.12 Option Subnegotiation

26.13 Sending Terminal Type Information

26.14 Terminatmg Subnegotiation

26.15 Sending A Characler To The Server

26.16 Displaying Incoming Data On The User's Terminal

26.17 Using Termcap To Control The User's Terminal

26.18 Writing A Block OfData To The Server

26.19 Interacting With The Client Process

26.20 Responding To lllegal Commands

26.21 Scripting To A File

26.22 Implementation OfScripting

26.23 Initialization OfScripting

26.24 Collecting Characters Of The Script File Name

26.25 Opening A Script File

26.26 Terminating Scripting

26.27 Printing Slatus Information

26.28 Summary

Chapter 27 Practical Hlnts And Technlques For UNIX Servers

27.1 Introduction

27.2 Operating In Background

27.3 Programming A Server To Operate In Background

27.4 Open Descriptors And Inheritance

27.5 Programming A Server To Close Inherited Descriptors

27.6 Signals From The Conlrolling TTY

27.7 Programming A Server To Change Its Controlling TTY

27.8 Moving To A Safe And Known Directory

27.9 Programming A Server To Change Directories

27.10 TheUNIXUmask

27.11 Programming A Server To Sel Its Umask

27.12 Process Groups

27.13 Programming A Server To Set Its Process Group

27.14 Descriptors For Standard 1/0

27.15 Prcgramming A Server To Open Standard Descriptors

27.16 Mutual Exclusion For The Server

27.17 Programming A Server To Avoid Multiple Copies

27.18 Recording A Server's Process ID

27.19 Programming A Server To Record Its Process ID

27.20 Waiting For A Child Process To Exit

27.21 Programming A Server To Wait For Each Child To Exit

27.22 Extraneous Signals

27.23 Programming A Server To Ignore Exfraneous Signals

27.24 Using A System Log Facility

27.24.1 Generating Log Messages

27.24.2 The Advantage Of Indirection And Standard Error

27.24.3 Limitations Of I/O Redirection

27.24.4 A Client-Server Solution

27.24.5 The Syslog Mechanism

27.24.6 Syslog Message Classes

27.24.7 Syslog Facilities

27.24.8 Syslog Priority Levels

27.24.9 Using Syslog

27.24.lO An Example Syslog Configuration File

Summary

Chapter 28 Deadlock And Starvation In Client-Server Systems

28.1 Introduction

28.2 Definition Of Deadlock

28.3 Difficulty OfDeadlock Detection

28.4 Deadlock Avoidance

28.5 Deadlock Between A Client And Server

28.6 Avoiding Deadlock In A Single Interaction

28.7 Starvation Among A Set Of Clients And A Server

28.8 Busy Connections And Starvation

28.9 Avoiding Blocking Operations

28.10 Processes, Connections. And Other Limits

28.11 Cycles Of Clients And Servers

28.12 Documenting Dependencies

28.13 Summary

Appendix 1 System Calls And Llbrary Routlnes Used With Sockets

Appendlx 2 Manipulation Of UNIX File And Socket Descriptors

暂无相关内容，正在全力查找中

暂无出版社相关信息，正在全力查找中！

暂无相关书籍摘录，正在全力查找中！

在线阅读地址：网络互连技术系列在线阅读

在线听书地址：网络互连技术系列在线收听

在线购买地址：网络互连技术系列在线购买

暂无原文赏析，正在全力查找中！

书籍介绍

内容简介

TCP/IP网络互连技术系列的第Ⅲ卷讨论客户/服

务器编程和应用.讲述了构筑所有分布式计算系统的客

户/服务器计算模型的基本概念，内容包括各种不同的

服务器设计方法，以及用来构造客户/服务器的各种工具

和技术，包括远程调用RPC。书中包括了用来说明每种

设计和工具的运行程序示例的源代码。

第Ⅲ卷有三个版本：分别对应于广为应用的BSD

套接字，AT&TTLI接口和WindowsSockets。本书

是BSD套接字版，在所有编程实例中使用BSDUNIX

套接字机制。