Síťový server

Pracovní režim

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.

Implementační technologie

Usually,thewebservercanadoptthefollowingfourimplementationtechnologies:

1)""Strategie okamžitého vytvoření, okamžitého zničení"", to znamená, že se server propojí s každým žádajícím klientem a vytvoří podproces pro každý požadavek klienta ke zpracování.

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)Server předem vytváří procesy pro více dětí a zpracovává požadavky klientů. Tato metoda se nazývá „předvytvoření“.

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.

Složení a rozdělení

Serverový software

Thedefinitionofserversoftwareisasmentionedabove,andtheserversoftwareworksinaclient-serverorbrowser-serverway,Therearemanyformsofservers,commonlyusedinclude:

Souborový server-jako Novell'sNetWare

Databázový server-jako je Oracledatabázový server, MySQL, PostgreSQL, MicrosoftSQLServer atd.

Network Server

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Mailserver-Sendmail,Postfix,Qmail,MicrosoftExchange,LotusDomino atd.

Webový server-jako Apache,thttpd,MicrosoftIIS atd.

FTPserver-Pureftpd, Proftpd, WU-ftpd, Serv-U, VSFTP atd.

Aplikační server-jako Bea'sWebLogic,JBoss,Sun'sGlassFish

Proxyserver-jakoSquidcache

Computernameconversionserver-suchasMicrosoft'sWINSserver

Serverový hardware

Mostserversusecomponentredundancytechnology,RAIDtechnology,memoryerrorcorrectiontechnologyandmanagementsoftware.High-endserversusemulti-processorsandsupportasymmetricalprocessorstructurewithmorethandualCPUs.Whenselectingserverhardware,inadditiontoconsideringthegradeandspecificfunctionpositioning,youalsoneedtofocusonunderstandingthemainparametersandcharacteristicsoftheserver,includingprocessorarchitecture,scalability,serverstructure,I/0capabilities,andfailurerecoverycapabilities.Servertypescanbedividedaccordingtomultiplestandards.

1.Rozdělenopodleúrovněaplikaceneboměřítka

●Server základní úrovně: Server nejnižší úrovně, používaný hlavně pro kancelářské služby souborů a tisku.

●Server na úrovni pracovní skupiny: vhodný pro sítě malého rozsahu, vhodný pro poskytování webu, pošty a dalších služeb pro malé a středně velké podniky.

●Servery na úrovni oddělení: servery střední třídy, vhodná středně velká podniková datacentra, webové stránky a další aplikace.

●Server podnikové třídy: Špičkový server s možnostmi superzpracování dat, vhodný pro databázový server velké sítě.

2.Rozděleno podle struktury serveru

●Desktopserver:alsoknownastowerserver,thisisthemosttraditionalstructurewithbetterexpansionsex.

●Server namontovaný v racku: Server namontovaný v racku je instalován ve standardní 19palcové skříni. Podle výšky jsou specifikace 1U (1U=1,75 palce), 2U, 4U a 6U.

●Bladeserver:Vysoká dostupnost,vysoká hustota a nízkonákladová serverová platforma navržená pro speciální aplikační odvětví a prostředí počítačů s vysokou hustotou.Každý "blade" je ve skutečnosti základní deska systému.

●Skříňový server: Podvozek má skříňový typ, na server je třeba nainstalovat mnoho modulových komponent.

3.Dividedaccordingtohardwaretype

●Dedicatedserver:aspeciallydesignedhigh-levelserverwithaspecialoperatingsystem(suchasUNIX,MVS,VMS,etc.)),whichismainlyusedfordatabaseservicesandInternetbusiness.Generally,professionalcompaniesprovideafullsetofsoftwareandhardwaresystemsandfullservice.

●PCserver:AserverwithIntelorMotoroladedicatedprocessorsasthecore,compatiblewithavarietyofnetworkoperatingsystemsandnetworkapplicationsoftware,anditsperformancecanreachthelevelofmid-rangeRISCservers.

Význam slova diskriminace

Sometimes,wewillseeanotherconceptofwebserverwhichisdifferentfromwebserver.Thesetwodefinitionscancauseconfusion.Theformerreferstothecomputerusedforthewebsite,andthelatterreferstotheprogramthatincludessoftwaresuchasApache,whichrunsonacomputertomanagewebpagecomponentsandrespondtowebbrowserrequests.

Bezpečnostní opatření

(1)Makeabackupoftheserversystemfortimelyrestoration.

(2)Closeunnecessaryserviceportsandonlyopentherequiredports.

(3)Securitycheckforabnormalprocess,installandupdateserveroperatingsystemintime.

(4) Nainstalujte do systému software firewall a antivirový software.

(5)Openthelogservicetocheckthewhereaboutsofhackers.

(6)Implementationofencryptionandauthenticationsecuritytechnology.

Nepřímý vliv

Themajorsearchenginesarechoosingsomewebsiteswithbetteruserexperiencetomakebetterrankings.ThePVvalueofthewebsitedirectlyaffectstherankingofthewebsite.So,ifyouchooseaproductfromsuchahigh-qualityserverrenter,everyvisitorwillvisityourwebsiteataveryfastspeed,andthenaturalPVvaluewillbehigh.Thentheexperienceonyourwebsitewillnaturallybebetter.Ifeveryvisitorislikethis,thefriendlinessofthesearchenginewillgraduallyimprove.Thennaturallygivebetterweight.Therefore,high-qualitynetworkhostingspaceisthebasisforimprovingcustomerexperience.

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