高級(jí)操作系統(tǒng)全chapter3進(jìn)程間通信2016ados

高級(jí)AdvancedOperatingDistributedSystemsConceptsanddesign朱青QingZhu,DepartmentofComputerScience,RenminChapterInterprocessCommunication進(jìn)程間的通Teacher:QingZhu 朱青DepartmentofComputerScience,InformationSchool,RenminUniversity2DistributedSystems–ConceptsandDesign,GeorgeCouloris, Dollimore,andTimKindbergEdition3,4,?PearsonEducation2001,2005ThelectureisbasedonthisChapter 進(jìn)程間的3.0進(jìn)程及消息3.1進(jìn)程間的3.2客戶/服務(wù)器計(jì)算模3.4應(yīng)用4進(jìn)程及消息進(jìn)程進(jìn)程狀態(tài)消息進(jìn)程通信經(jīng)典操作系統(tǒng)簡(jiǎn)是計(jì)算機(jī)系統(tǒng)中的一個(gè)系統(tǒng)軟件，是一些程序模能以有效、合理的方式組織和管理計(jì)算機(jī)的軟硬使得用戶能夠靈活、方便、有效的使用計(jì)算機(jī)，6什么是操作系操作系統(tǒng)做什么#include#includeintmain(intargc,char{ oworld");return0;}操作系統(tǒng)提供一系列服務(wù)多任務(wù)設(shè)備控制用戶界硬件控安9OperatingExploitsthehardwareresourcesofoneormoreprocessorstoprovideasetofservicestosystemusersandI/OdevicesBasicTheprocessorControlstheactionsofExecutesdata-processing&logicoperationsI/OMovedatabetweenmemoryandexternaldevices(storage,hardware,terminals,…)

TheIsvolatile–contentsarelostwhenpoweredoffRandomThesystemProvidesamongprocessors,mainmemory,andI/Omodules進(jìn)程的進(jìn)程（Process）的定進(jìn)程的進(jìn)程（Process）的定進(jìn)程控制塊（ProcessControl>進(jìn)程控制塊（PCB）概念 系統(tǒng)利用PCB來控制和管理進(jìn)程，所PCB是系統(tǒng)感知進(jìn)程存在的唯一標(biāo)進(jìn)程與PCB是一一對(duì)應(yīng)程序與進(jìn)程更 描述并發(fā)，而程序不進(jìn)程是由程序和數(shù)據(jù)+PCB一個(gè)程序可對(duì)應(yīng)多個(gè)進(jìn)程，反之亦進(jìn)程的基本狀態(tài)及 等待發(fā)就緒

某 已經(jīng)發(fā)

等待運(yùn)行態(tài)進(jìn)程占有CPU，并在CPU上運(yùn)就緒態(tài) 等待態(tài)（Blocked）：阻塞態(tài)、掛起態(tài)、凍結(jié)態(tài)、睡眠 五狀態(tài)進(jìn)程模準(zhǔn)備退出：父進(jìn)程可中止子進(jìn)消息傳進(jìn)程交互的兩個(gè)基本要同步：互斥進(jìn)程間需同步。同步指對(duì)進(jìn)程執(zhí)行時(shí)序通信：合作進(jìn)程間交換信消息傳進(jìn)程通信的一種常用方適用范圍廣，可用于多核、SMP由原語對(duì)“send（發(fā)送）和receive（接收）”提receive(源信息實(shí)現(xiàn)形式有多 MessageTable5.5DesignCharacteristicsofMessageSystemsforInterprocessCommunicationand消息傳遞的同只有當(dāng)一個(gè)進(jìn)程發(fā)送消息之后，接收者才能調(diào)用send原語的兩種可能結(jié)發(fā)送者進(jìn)程被阻塞，直到這個(gè)消息被接調(diào)用receive原語接收者進(jìn)程接收消息時(shí)，消息已發(fā)出，接收三種組合方“阻塞send，阻塞receive”方式，即“會(huì)（如打用的組合（如服務(wù)器提供資源，收發(fā)）要求任何一方等待。：信息可能會(huì)丟失（如貼/看小）誤可能會(huì)導(dǎo)致進(jìn)程重復(fù)傳遞消息，消耗系統(tǒng)資源。且必須使用應(yīng)答消息以消息丟失或發(fā)送者進(jìn)程失效，會(huì)導(dǎo)send原語receive直接尋址發(fā)送者在發(fā)送時(shí)給出了接收者進(jìn)程消息傳遞的間接尋址發(fā)送者將消息發(fā)送到共享的信箱中臨時(shí)保管，接收者從信箱中獲得這些消耦合方式：“一對(duì)一”、“多對(duì)一”、進(jìn)程與信箱的關(guān)聯(lián)：靜態(tài)方式（端口）和動(dòng)態(tài)方式（使用連接原語connect和IndirectProcess單機(jī)系分布式系定長格變長格消息頭——消息類型、目標(biāo)ID、消息體——消息目標(biāo)目標(biāo)優(yōu)先級(jí)原同send——阻塞、無阻receive——阻塞、無阻尋間靜動(dòng)所有消息傳遞實(shí)現(xiàn)通信/格內(nèi)長度——排隊(duì)規(guī)優(yōu)先使用“無阻塞send，阻塞receive”組一組進(jìn)程共 個(gè)信箱box，信箱被初始化為一 每個(gè)進(jìn)程在進(jìn)入臨界區(qū)前，首先嘗試接收消息，每次只有接收到消息的那個(gè)進(jìn)程才可以進(jìn)入臨界區(qū)）消息函數(shù)似在進(jìn)程間傳遞一個(gè)可使用臨界區(qū)的Buffer問題描述（生產(chǎn)者/消費(fèi)者問題若干進(jìn)程通過無限/有限的共享緩沖區(qū)交換數(shù)一組“生產(chǎn)者”進(jìn)程不斷另一組“消費(fèi)者共享緩沖區(qū)無限/共有N4生產(chǎn)semaphoren=0;*緩沖區(qū)中semaphores=1;/*互斥*/voidproducer(){while(true){}

voidconsumer(){while(true){}}voidmain(){ 有限緩沖區(qū)的生產(chǎn)者/消費(fèi)生產(chǎn)者N/*programmutualexclusion*/constintn=/*進(jìn)程數(shù)*/;voidP(inti*進(jìn)程i*/messagemsg;while(true){

voidmain(){send(box,null);parbegin(P(1),…,P(n));}receive(box,msg);/*信箱空時(shí)被阻塞/*臨界區(qū)send(box,/*其余部分*/;}消息傳遞實(shí)現(xiàn)生產(chǎn)者-/*互斥程序constintcapacity=/*緩沖區(qū)容量*/;messagenull=/*空消息*/;voidproducer(){messagepmsg;while(true){receive(mayproduce,pmsg);send(sume,}}/*互斥程序constintcapacity=/*緩沖區(qū)容量*/;messagenull=/*空消息*/;voidcomsumer(){messagecmsg; send(mayproduce,null);}}消息傳遞實(shí)現(xiàn)生產(chǎn)者-voidmain({for(inti=1;i<capacity;i++)send(mayproduce,null);}/*初始時(shí)：mayconsume信箱為空，mayproduce信箱則被null信號(hào)填滿Chapter 進(jìn)程間的3.0進(jìn)程及其狀態(tài)轉(zhuǎn)3.1進(jìn)程間的3.2客戶/服務(wù)器計(jì)算模3.4應(yīng)用RMI,RMI,RPC,ExternaldataExternaldataRequest-replyRequest-replyOperatingsystem,networkRMI(remotemethodinvocation),RPC(remoteprocedureInterprocessCommunication(進(jìn)程間的通信Point-to-pointmessagepassingistypicallybasedontwomessagecommunicationoperations(subroutines).在點(diǎn)Send:Aprocesscopiesamessage(asequencebytes)intothe(ing)bufferofaremoteReceive:Aprocesscopiesamessagefromthe(bufferofitssystemintoitslocal接收：進(jìn)程消息從系統(tǒng)的緩沖區(qū)到本地內(nèi)存Typically,ReceivemustbecalledbeforethecorrespondingSend.在發(fā)送之前，相應(yīng)的接收需被調(diào)用Unbufferedcommunication:IfareceivehasnotcalledbeforethemessagearrivesitisAlternatively,someingmessagesarekepttemporarilyinabuffer(mailbox)assumingthatasuitablereceivewillbecalled?soon“.Otherwisethereisatime-outorabufferFailuremodelCommunicationSynchronousCommunication:ThesendingandreceivingprocessessynchronizeeachotherateveryTheSendandtheReceiveoperationsareTheSendprocessisblockeduntilthecorrespondingReceiveisissued.發(fā)送進(jìn)程阻塞直到發(fā)生了相應(yīng)的接收TheReceiveprocessisblockeduntilamessageAsynchronousCommunication異步Thesendingprocessisallowedtoproceedassoonasthemessagehasbeensenttotheoutgoing(local)TheSendoperationisnon-TheReceiveoperationmaybeeitherblockingInterprocessMessageDestination:(Internetaddress,localport)Reliability:reliablecommunicationintermsofvalidityandintegrity.Ordering:Someapplicationsrequirethatmessagesbedeliveredinsenderorder.ThedeliveryofmessagesoutofsenderorderinwhichisregardedasafailurebysuchFigureSocketsand

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Internetaddress=

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Internetaddress=SocketsareendpointsforcommunicationTheyoriginatefromUNIXbutarealsofoundin套接字源于UNIX，也在其他OSTheyareusedbyUDPandTCP它被用于UDPandEachsocketisassociatedwithaparticularInterprocesscommunicationconsistsoftransmittingamessagebetweenasocketinoneprocessandasocketinanotherprocess.AsocketmustbeboundtoalocalportandanInternetaddressofthecomputeronwhichitruns.套接字必須綁定到計(jì)算機(jī)的一個(gè)InternetAprocessmayusemultipleportnumbersforPortscannotbesharedbydifferentprocesses.不同進(jìn)程 Exception:IPmulticastsUDP)IPUDPisunreliableanddoesnotsupportacknowledgementsUDP是不具有可靠性，不支持確認(rèn)和重Ifamessagedoesnotarrive,afailure如果消息無法到達(dá)，故障發(fā)Mostenvironmentssupportamessagesizeof大多數(shù)環(huán)境支持的消息包大小為Largermessagesmustbe大消息必須被分Thereceivingprocessneedstospecifyanarrayforthe接收消息需要列入消息數(shù)Themessageistruncateditistoo太長的消息需要被截UDPusesnon-blockingsendsandblockingUDP數(shù)據(jù)報(bào)使用非阻塞send和阻塞Amessageis cedinaqueueforthesocketandcanbecollectedbyafuturereceive.消息被放置在socketTime-outscanbesetonThemessageisdiscardedifthenosocketisboundtothereceivingport如果套接字不被綁定到接收端消AreceivegetsanymessageaddressedtothisTCPisreliableandusesanacknowledgementSlidingwindowTheTCPstreamistransmittedasoneormoreIPpackets(implementationdependent).TCPtriestomatchthespeedoftheprocesseswritingtoorreadingfromastream:FlowAsendermaybeblockedDuetomessageidentifierstherecipientcandetectandrejectduplicatesandreordermessageifnecessary.由于消息標(biāo)示接收者能探測(cè)和 ApairofcommunicatingprocessmustestablishconnectionbeforeusingaOncetheconnectionexistsnoInternetaddressesandportsarenecessarytowritetoorreadfromthe一旦連接建立，對(duì)于流的讀寫，Internet地址和端口可以不需TheprocessesmustagreeonthecontentoftheFailureModelsforUDPandUDPusesachecksumtoensurethatamessageisUDP使用校驗(yàn)確保消息不再破Somemessagesmaygetlost(omission一些消息可能被丟失（冗長失效MessagesmayarriveoutofsenderTCPuseschecksumstodetectandrejectcorruptTCP使用校驗(yàn)診斷 TCPusessequencenumberstodetectandduplicatepackets.TCP使用序列號(hào)診斷 重復(fù)的包TCPusestimeoutsandretransmissionstodealwithAfteralongtimewithoutacknowledgementTCPdeclaretheconnectiontobe長時(shí)間沒有被確認(rèn)的TCP將宣布連接中Theprocessescannotdistinguishbetweennetworkfailureandfailureoftheprocessattheotherendoftheconnection.Inthiscaseaprocess lwhetheritsrecentmessageshavebeenFigureMiddlewareRMIandRPC

Figure sendsamessagetotheserverandgetsaimport.*;importpublic publicstaticvoid//argsgivemessagecontentsandserveraSocket=null;try{aSocket=new);byte[]maHost=FigureUDPserverrepeatedlyreceivesarequestandsendsitbacktoimport.*;publicclasspublicstaticvoidaSocket=null;aSocket=new6789);byte[]buffer=newrequest=newFigure makesconnectiontoserver,sendsrequestandreceivesimport.*;publicclass publicstaticvoidmain(Stringargs[]){//argumentssupplymessageandhostnameofSockets=null;intserverPorts=newin=new(}.getInputStream(Figure4.6TCPservermakesaconnectionforeachandechoesthe’simportimportpublicclassTCPServerpublicstaticvoidmain(Stringargs[]){try{intserverPort=7896;ServerSocketlistenSocket=newServerSocket(serverPort);while(true){ Socket=listenSocket.accept();Connectionc=new }}catch(IOExceptione){System.out.println("Listen}}//thisfigurecontinuesonthenextFigure4.6classConnectionextendsThreadDataInputStreamin;SocketSocket;publicConnection(SocketaSocket)trySocket=ain=new out=newDataOutputStream( }catch(IOExceptione)}publicvoidtry //anechoStringdata=}catch(EOFExceptione)}catch(IOExceptione)}finally{try{Socket.close();}catch(IOExceptione){/*close}}FigureSocketsusedfordatagrams用于數(shù)據(jù)包的套Sendinga Receivingasendto(s,sendto(s,"message", ServerAddressandAddressaresocketFigureRequestinga Listeningandacceptingabind(s,write(s,"message",sNew=accept(s, write(s,"message",ServerAddress AddressaresocketChapter 進(jìn)程間的3.0進(jìn)程及其狀態(tài)轉(zhuǎn)3.1進(jìn)程間的3.2客戶/服務(wù)器計(jì)算模3.4應(yīng)用客戶/服務(wù)器計(jì)算1網(wǎng)絡(luò)計(jì)算(1)以大型機(jī)為中心的計(jì)算模（分時(shí)共享模式(time- 從主機(jī)返回的所有結(jié)果，都顯示在屏幕網(wǎng)絡(luò)計(jì)算模(2)以服務(wù)（資源共享模式resource-形式：共享共同的應(yīng)用、數(shù)據(jù)，以 盤、等。網(wǎng)絡(luò)計(jì)算模(3)小型化和客戶機(jī)/服務(wù)器計(jì)算end)服務(wù)器部客戶機(jī)和服務(wù)器工作在不同的邏輯實(shí)體中，協(xié)調(diào)工作通信時(shí)，客戶即可索取信息，它依賴于服務(wù)器執(zhí)行客不能完成或不能有效完成的工服務(wù)器方隨時(shí)等待客戶機(jī)提交申請(qǐng)的信息，進(jìn)行信息技術(shù)特點(diǎn)和計(jì)算機(jī)能力來執(zhí)行一個(gè)特定C/S（1）客戶機(jī)的特點(diǎn)B)一個(gè)C/S模式下，可包括多個(gè)客戶C)客戶機(jī)使用標(biāo)準(zhǔn)語言進(jìn)行信D)客戶機(jī)可使用緩沖或優(yōu)化E)客戶機(jī)通過一個(gè)進(jìn)程間通訊機(jī)制C/S（2）C/S客戶/服務(wù)器的A)桌面上的B)優(yōu)化C)優(yōu)化網(wǎng) Chapter 進(jìn)程間的3.0進(jìn)程及其狀態(tài)轉(zhuǎn)3.1進(jìn)程間的3.2客戶/服務(wù)器計(jì)算模3.4應(yīng)用實(shí)例Socket網(wǎng)絡(luò)概TCP/IP使用TCP Socket中的系統(tǒng)1.終端登錄與網(wǎng)絡(luò)登終端登錄：login: 網(wǎng)絡(luò)登錄 文件I/O和網(wǎng)絡(luò)文件六種輸入/輸出服務(wù)open,creat,close,read,write和網(wǎng)絡(luò)I/O：（比文件I/O復(fù)雜1)客戶/服務(wù)器關(guān)系是非對(duì)稱的，在初始化2)網(wǎng)絡(luò)I/O有面向連接與非連接的。前者很網(wǎng)絡(luò)3網(wǎng)絡(luò)中名字比標(biāo)識(shí)更重要。文件繼承了fd4)UNIX的文件I/O是面向流的，而網(wǎng)絡(luò)有面向流與機(jī)制。如：XNS,IPX/SPX,TCP/IP。廣域網(wǎng)局域網(wǎng)集中模式（信息的處理和控制是集中的對(duì)等模式（信息的處理和控制都是分布的TCP/IP概網(wǎng)HostHostwithHostwith

網(wǎng)絡(luò)模

網(wǎng)絡(luò)應(yīng)用層:包含所有的協(xié)議，如虛擬終端協(xié) NET協(xié)議：允許用戶登錄到另一臺(tái)UNIX機(jī)器FTP協(xié)議：用于傳輸文SMTP協(xié)議：用來傳送，常見的服務(wù)器端程序netscape等公司制作的程序，也有免費(fèi)使用的sendmail程；還有系統(tǒng)服務(wù)DNS協(xié)議，組傳送協(xié)議NNTP，用WWW的超文本傳輸協(xié)議HTTP等網(wǎng)絡(luò)傳輸層:主要功能使源和目的主機(jī)之間可以進(jìn)行會(huì)話。該層（a）IP協(xié)議族（Intntotool）物理層TCP/IPTCP/IPTCP（傳輸控制協(xié)議）o議。不保證數(shù)據(jù)報(bào)一定能到達(dá)目的地。Socket描述與Socket（進(jìn)程間通 ）支持下列通信協(xié)socket索引值。socket描述符指向socket有BSDUNIX中socket調(diào)用，可以新建一個(gè)socket用，完成建立通信的過程 2socket客戶/服務(wù)器模TCPConnection

3-way

服務(wù)端進(jìn)程（到服務(wù)器(1)使用socket調(diào)用得到一個(gè)描述(3)服務(wù)端使用listen調(diào)用等待服務(wù)請(qǐng)求服務(wù)端進(jìn)程(5)服務(wù)端使用新的socket進(jìn)行再到accept調(diào)用處等待另接?？蛻舳诉M(jìn)(1)使用socket調(diào)用得到一個(gè)socket描述(3)通過socket描述符進(jìn)行讀寫操管套調(diào)用類型（無連接協(xié)議UDPConnection Server創(chuàng)建一個(gè)調(diào)用recvfrom接收客客戶端創(chuàng)建一個(gè)再使用sendto向服務(wù)端進(jìn)程發(fā)出請(qǐng)求使用recvfrom得到返connect（建立連接write、read及send和recv和bind(將一個(gè)名字綁定到一個(gè)Socket調(diào)用socket用來建立一個(gè)通信的端點(diǎn)int ,inttype,int頭文件：#include#includeSocket的系統(tǒng) 參數(shù)type指通訊類型為SOCK_DGRAM的socket支持UDPConnect系統(tǒng)的格intconnect(ints,conststructsockaddr*name,int頭文件：#include#include第一個(gè)參數(shù)s是一個(gè)打開的socketConnect系統(tǒng)調(diào)如果該socket的類型是SOCK_STREAM,與另一socket建立連接 Connect系統(tǒng)調(diào)該結(jié)構(gòu)如structsockaddru_charsa_len;/*總長度u_charsa_family;/*地址簇charsa_data[14];/*實(shí)際，地址值第三個(gè)參數(shù) 地址的長度3write、read及close調(diào)在網(wǎng)絡(luò)程序中使用wi、ad和los.在使用TCwt來sok度一般將發(fā)送的數(shù)據(jù)到witread第一個(gè)參數(shù)也是socket描述第二個(gè)參數(shù)是存放讀入數(shù)據(jù)的用戶緩沖地址，第三個(gè)參數(shù)緩沖的長度也使用一個(gè)接收數(shù)據(jù)緩沖，當(dāng)用戶進(jìn)程使用read調(diào)用 用戶緩沖大小的數(shù)據(jù)。當(dāng)客戶端或服務(wù)端使用UDP協(xié)議程序也可以使用read來接收UDP數(shù)據(jù)報(bào)，但當(dāng)消息的長度于用戶緩沖時(shí) 僅為read調(diào) 用戶緩沖大小的數(shù)，剩余數(shù)據(jù)將被Close該描述符有多個(gè)（與打開文件相同），則將該socket的數(shù)減一，如果數(shù)減為0，Send和send和sendto用來從一個(gè)socket發(fā)送一個(gè)消o格式intsend(ints,constvoid*msg,intlen,unsignedintflags);intsendto(ints,constvoid*msg,intlen,unsignedintflags,conststructsockaddr*to,頭文件：#include#include調(diào)用send和sendto用來發(fā)送一個(gè)消息到另一send調(diào)用只用于處于連接狀態(tài)的參數(shù)s是一個(gè)socket描述符。在sendto Recv和格式如intrecv(ints,void*buf,intlen,unsignedintintrecvfrom(ints,void*buf,intlen,unsignedintflags,structsockaddr*from,int*fromlen);頭文件：#include#include參數(shù)s為要接收數(shù)據(jù)的socket參數(shù)len用戶緩沖的大小系統(tǒng)調(diào)用recvfrom用來從一個(gè)socket接收消，不管這個(gè)socket是否面向連接參數(shù)from非空，并且該socket不是面向連接，則recvfrom調(diào)用返回時(shí)，參數(shù)from中存放是消息的源地址shutdown調(diào)用該調(diào)用將關(guān)閉一個(gè)全雙工連接的端格式如下：intshutdown(intsint頭文件：#include如果參數(shù)how為1，則繼續(xù)發(fā)送數(shù)據(jù)。如how為2， 在該socket上接收或發(fā)送數(shù)據(jù)Bind調(diào)bind調(diào)用將一個(gè)名字綁定到一個(gè)socket格式如下：intbind(intsstruct*my_addr,int頭文件：#include#includebind調(diào)用為一個(gè)未命名的socket分配即：bind調(diào)用是給套接字smy_addr，這個(gè)my_addr地址的長度為。對(duì)于不同通信域的地址聯(lián)編的規(guī)則是不，這里還是以internet域?yàn)橹?/p>

listen調(diào)用該調(diào)用在一個(gè)socket偵聽連格式如下：intlisten(intsint頭文件：#include或SOCK_SEQPACKET類型的socket上。accept調(diào)用在指定的socket上接受接請(qǐng)求格式如下：intaccept(intsstructsockaddr*addr頭文件：#include#include參數(shù)s是要接受連接請(qǐng)求的socket，這個(gè)socketsocket調(diào)用創(chuàng)建第二個(gè)參數(shù)addr是用來存放返回值的，在使用IP地址，使用sockaddr_in結(jié)構(gòu)，accept返回時(shí)，該結(jié)的是連接實(shí)體的第三個(gè)參數(shù)addrlen在調(diào)用前用來addr的大小，調(diào)用后返回精確的addr的長

DNS(服務(wù)通過因特網(wǎng)名字得到名字所代表的IP$IP四層UNIXIPSocketAPIintsocket(intfamily,inttype,intCreatesanetworkplugpointthatenablesthe/serverintconnect(intsockfd,conststructsockaddr*servaddr,socklen_taddrlen)Enablesatoconnecttoabind(intsockfd,conststructsockaddr*myaddr,socklen_tAllowsaservertospecifytheIPaddress/port_numberassociatedwithaSocketAPIintlisten(intsockfd,intAllowstheservertospecifythatasocketcanbeusedtointaccept(intsockfd,structsockaddr*_addr,socklen_tAllowsaservertowaittillanewconnectionrequestintclose(intTerminatesanyconnectionassociatedwithasocketandreleasestheSocketAPIintread(intsockfd,void*buf,intReaddatafromaTCPintwrite(intsockfd,void*buf,intWritedatatoaTCPintsendto(intsockfd,void*msg,…SendaUDPmessageonasockettospecifiedintrecvfrom(intsockfd,void*buf,…RecvaUDPmessageonasocketalongwithaddressofsendingSimilarlycheckmanpagesforsendmsg(),ConvertingBetweenAddressFromASCIIto“4”32-bitnetworkbyteorderedinet_aton(…)withinet_pton(…)withIPv4andFromnumericto32-bitvalueinet_ntoa(…)withinet_ntop(…)withIPv4andNote–inet_addr(…)cannothandlebroadcastaddressGettingIPaddress/portfromintgetsockname(intsockfd,structsockaddr*localaddr,socklen_t*addrlen)GetthelocalIP/portboundtointgetpeername(intsockfd,structsockaddr*remoteaddr,socklen_t*addrlen)GettheIP/portofremoteNameIPstructhostent*gethostbyaddr(void*addr,size_tlen,intConvertsfromIPaddr structhostent*gethostbyname(charConverts nametoIPChapter 進(jìn)程間的3.0進(jìn)程及其狀態(tài)轉(zhuǎn)3.1進(jìn)程間的3.2客戶/服務(wù)器計(jì)算模3.4應(yīng)用實(shí)例應(yīng)用實(shí) o,world!”.簡(jiǎn)單的流服務(wù)(Ex37.c/*server#include#include#include#include#incl