Режим на работа
InastandardC/Smodecomputernetwork,thenetworkservercanworkintwodifferentmodes:iterativemodeandconcur-rentmode).Thecircularmethodisthatonlyoneserverprocesscanrunintheserveratatime.Whenmultipleclientsrequestservice,theserverprocessrespondsintheorderoftherequest;theconcurrentmethodcanrunmultipleserverprocessesintheserveratthesametime,andEachserverprocessrespondstoaspecificclientrequest.
Thesetwoservermodelshavetheirownadvantagesanddisadvantages.Whentheservicetakesalongtime,ifacyclicserverisused,theclientwillnotreceiveafastresponse,andtheclientrequestmayevenberejected.However,thiskindofserverconsumesfewsystemresourcesandisrelativelysimpletoimplement.Theconcurrentservercreatesachildprocessforeachrequest,whichcanensurethatmultipleclientrequestsareprocessedatthesametime.Theuseofthisservermodelgenerallydoesnotcausetherejectionofclientrequests,butiffrequentchildprocessesarecreated,theburdenontheserverwillbeincreased..Inactualnetworkapplications,theserverneedstoprocessmultipleclientrequestsatthesametime,soitusuallyadoptsaconcurrentmethod.
Технология на внедряване
Usually,thewebservercanadoptthefollowingfourimplementationtechnologies:
1)""Стратегия за незабавно създаване,незабавно унищожаване"", тоест сървърът се свързва с всеки заявител и създава подпроцес за всяка заявка на клиента за обработка.
Aftertheconcurrentserverisstarted,thesystemdaemonmonitorswhetheraclientinitiatesaconnectionrequestonafixedport.Ifaclient'srequestisreceived,theserverdaemoncreatesachildprocesstohandletheclient'srequest,andthedaemoncontinuestomonitorconnectionrequestsfromotherclientsontheoriginalport.Afterthechildprocessfinishesservingtheclient,itclosestheconnection,releasestheresourcesitoccupied,andautomaticallyexits.
Obviously,thiskindofconcurrentserverhasthefollowingshortcomings:(1).Thesystemtimeisextended.Beforeprovidingservicestotheclientprocess,theserverparentprocessneedstocreateanewchildprocess,sotheclientprocessmustwaitatleastforthedelayofcreatingachildprocess.Forsomenetworkapplicationswithhighreal-timerequirements,suchatimedelaycannotbetolerated;(2)Thesourceoffailureislarge.Foreachclientprocessrequest,theserverparentprocessmustcreateanewchildprocess.Eachchildprocesstakesupalmostthesameresourcesastheparentprocess.Therefore,inmanysystems,thenumberofcreationprocessesislimited;(3)Theutilizationrateofthesourceislow.Thelackofaneffectiveinter-processcommunicationmechanismbetweentheparentprocessandthechildprocessmakestheparentprocessunabletoeffectivelycontrolthechildprocess.Atthesametime,thechildprocessterminatesitselfaftercompletingtheservicetotheclientprocessandcannotbereused.
2)Сървърът създава предварително множество дъщерни процеси, а дъщерните процеси обработват клиентски заявки. Този метод се нарича „предварително създаване“.
Theserverbasedonthe"pre-creation"technologysolvestheproblemTheclientprocesswaitsforthedelayproblem,buttherearealsothefollowingproblems:(1)Theserveralwaysmaintainsafixednumberofchildprocesses,soevenifthereisnoconnectionrequestfromtheclientprocess,thesystemwillmaintaintheseidleprocesses,causingdamagetothesystem.Wasteofresources;(2)Thecivilserveronlyprovidesafixednumberofchildprocesses.Ifthenumberofclientconnectionrequestsexceedsthenumberofchildprocesses,thentheclientprocessmustwaitfortheserviceterminationofotherclientprocesses,whichmaycausegreaterdelay;(3Ifachildprocessexitsabnormally,thenumberofclientprocessconnectionsthattheservercansupportatthesametimewillbereducedby1,whichwillweakentheserver’sconcurrentprocessingcapabilities.
Inordertoovercometheaboveproblems,youcanusedynamic"pre-Creation"technology,thatis,theserverparentprocesscreatesacertainnumberofchildprocessesbasedontheresourcestatusofthesystemorthenumberofuserrequests,andthenputsthemina"pool"toforma"processpool".Whenaclientrequestarrives,Insteadofcreatinganewprocesstoserveit,itselectsanidleprocessfromthe"pool"toserveit.Aftertheserviceiscompleted,theprocessenterstheidlestate.Ifthenumberofclientssimultaneouslyrequestingisgreaterthanthenumberofprocessesintheprocesspool,thesystemAccordingtothestateofsystemresources,thenumberofprocessesinthe"pool"canbeincreased,orclientrequestscanbequeuedorsimplydiscarded,dependingonthespecificsituation.Theuseofthistechnologyspeedsuptheserver'sresponsetimeandimprovesresourcesTheutilizationefficiencyofthiseffectivelypreventstheserverfromcrashingduetoexcessiveclientrequests.
3)TheserverusesthefunctionselecttoimplementI/Omultiplexingformultipleclientconnections;
Inadditiontomulti-processormulti-threadedimplementationofconcurrentservers,I/Omultiplexingtechnologycanalsobeused.Throughthistechnology,thesystemkernelbuffersI/Odata.WhencertainI/OWhenready,thesystemwillnotifytheapplicationthattheI/Oisreadableorwritable,sothattheapplicationcancompletethecorrespondingI/Oimmediately,insteadofwaitingforthesystemtocompletethecorrespondingI/Ooperation,sothattheapplicationdoesnothavetowaitI/Ooperationisblocked.
Comparedwithmulti-processormulti-thread,thebiggestadvantageofI/Omultiplexingtechnologyisthatthesystemoverheadissmall.Thesystemdoesnotneedtocreateprocessesandthreads,anddoesnotneedtomaintaintheseProcessesandthreads,therebygreatlyreducingtheoverheadofthesystem.
4)Thesuperserveractivatesthestrategyoftheauxiliaryserver.
Thismodeofserverrequiresmultipleservers,oneofwhich(Thesuperserverwaitsfortherequestfromtheclientonawell-knownport.Oncethesuperserverreceivestheclient'srequest,itimmediatelyactivatesaslaveserverandtransferstheuser'srequesttotheactivatedslaveserver.ThentheslaveserverandtheclientprogramKeeptheconnectionandcompletetheprocessingoftheclient'srequest,andthesuperservercontinuestomonitortheclient'srequestontheoriginalport.
Inthisservermodel,eachslaveserverisstillaconcurrentserver,sotheconcurrencyofthesystemissignificantlyimproved.However,theuseofthisservermodelrequiresanincreaseinthenumberofservers,whichincreasesthecostofthesystemandisusuallyusedforsomeaccessArelativelylargenumberofwebservers.
Състав и деление
Сървърен софтуер
Thedefinitionofserversoftwareisasmentionedabove,andtheserversoftwareworksinaclient-serverorbrowser-serverway,Therearemanyformsofservers,commonlyusedinclude:
Файлов сървър като Novell'sNetWare
Сървър на база данни - като Oracledatabaseserver, MySQL, PostgreSQL, MicrosoftSQLServer и др.
p>
Mailserver-Sendmail, Postfix, Qmail, MicrosoftExchange, LotusDomino и др.
Уеб сървър като Apache, thttpd, MicrosoftIIS и др.
FTP сървър-Pureftpd, Proftpd, WU-ftpd, Serv-U, VSFTP и др.
Сървър за приложения като Bea'sWebLogic,JBoss,Sun'sGlassFish
Прокси сървър като Squidcache
Computernameconversionserver-suchasMicrosoft'sWINSserver
Сървърен хардуер
Mostserversusecomponentredundancytechnology,RAIDtechnology,memoryerrorcorrectiontechnologyandmanagementsoftware.High-endserversusemulti-processorsandsupportasymmetricalprocessorstructurewithmorethandualCPUs.Whenselectingserverhardware,inadditiontoconsideringthegradeandspecificfunctionpositioning,youalsoneedtofocusonunderstandingthemainparametersandcharacteristicsoftheserver,includingprocessorarchitecture,scalability,serverstructure,I/0capabilities,andfailurerecoverycapabilities.Servertypescanbedividedaccordingtomultiplestandards.
1.Разделено според нивото на приложение или скала
●Сървър от начално ниво: Най-ниският сървър, използван главно за услуги за офис файлове и печат.
●Сървър на ниво работна група: подходящ за мрежи от малък мащаб, подходящ за предоставяне на уеб, поща и други услуги за малки и средни предприятия.
●Сървъри на ниво отдел: сървъри от среден клас, подходящи за центрове за данни на средно големи предприятия, уебсайтове и други приложения.
●Сървър от корпоративна класа: Сървър от висок клас, със супер възможности за обработка на данни, подходящ за широкомащабни сървъри на мрежови бази данни.
2.Разделени според структурата на сървъра
●Desktopserver:alsoknownastowerserver,thisisthemosttraditionalstructurewithbetterexpansionsex.
●Сървър, монтиран в шкаф: Монтираният в шкаф сървър е инсталиран в стандартен 19-инчов шкаф. Според височината има спецификации 1U (1U=1,75 инча), 2U, 4U и 6U.
●Блейд сървър: Това е сървърна платформа с висока достъпност, висока плътност и ниска цена, предназначена за индустрии със специални приложения и компютърни среди с висока плътност. Всеки "блейд" всъщност е дънна платка на системата.
●Сървър тип шкаф: Шасито е тип шкаф и много компоненти на модула трябва да бъдат инсталирани в сървъра.
3.Dividedaccordingtohardwaretype
●Dedicatedserver:aspeciallydesignedhigh-levelserverwithaspecialoperatingsystem(suchasUNIX,MVS,VMS,etc.)),whichismainlyusedfordatabaseservicesandInternetbusiness.Generally,professionalcompaniesprovideafullsetofsoftwareandhardwaresystemsandfullservice.
●PCserver:AserverwithIntelorMotoroladedicatedprocessorsasthecore,compatiblewithavarietyofnetworkoperatingsystemsandnetworkapplicationsoftware,anditsperformancecanreachthelevelofmid-rangeRISCservers.
Дискриминация на думата
Sometimes,wewillseeanotherconceptofwebserverwhichisdifferentfromwebserver.Thesetwodefinitionscancauseconfusion.Theformerreferstothecomputerusedforthewebsite,andthelatterreferstotheprogramthatincludessoftwaresuchasApache,whichrunsonacomputertomanagewebpagecomponentsandrespondtowebbrowserrequests.
Предпазни мерки
(1)Makeabackupoftheserversystemfortimelyrestoration.
(2)Closeunnecessaryserviceportsandonlyopentherequiredports.
(3)Securitycheckforabnormalprocess,installandupdateserveroperatingsystemintime.
(4) Инсталирайте софтуерна защитна стена и антивирусен софтуер в системата.
(5)Openthelogservicetocheckthewhereaboutsofhackers.
(6)Implementationofencryptionandauthenticationsecuritytechnology.
Косвено влияние
Themajorsearchenginesarechoosingsomewebsiteswithbetteruserexperiencetomakebetterrankings.ThePVvalueofthewebsitedirectlyaffectstherankingofthewebsite.So,ifyouchooseaproductfromsuchahigh-qualityserverrenter,everyvisitorwillvisityourwebsiteataveryfastspeed,andthenaturalPVvaluewillbehigh.Thentheexperienceonyourwebsitewillnaturallybebetter.Ifeveryvisitorislikethis,thefriendlinessofthesearchenginewillgraduallyimprove.Thennaturallygivebetterweight.Therefore,high-qualitynetworkhostingspaceisthebasisforimprovingcustomerexperience.