Workingmode
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.
Implementationtechnology
Usually,thewebservercanadoptthefollowingfourimplementationtechnologies:
1)" "Instantcreatio, instantis destructio- nis", id est, servator Connectendi in petitione clientis, et efficiat sub-processus postulationis processum.
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 multiplicat processum infantis in processu et processu petitionis. Haec methodus vocatur "prae-creatio".
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.
Compositionanddivision
Serversoftware
Thedefinitionofserversoftwareisasmentionedabove,andtheserversoftwareworksinaclient-serverorbrowser-serverway,Therearemanyformsofservers,commonlyusedinclude:
Fileserver-suchasNovell'sNetWare
Databaseserver-suchasOracledatabase server,MySQL,PostgreSQL,MicrosoftSQLServer,etc.
p>
Mailserver-Sendmail,Postfix,Qmail,MicrosoftExchange, LotusDomino,etc.
Webserver-suchasApache,thttpd,MicrosoftIIS,etc.
FTPserver-Pureftpd,Proftpd,WU-ftpd,Serv-U,VSFTP,etc.
Applicationserver-suchasBea'sWebLogic,JBoss,Sun'sGlassFish
Proxyserver-suchasSquidcache
Computernameconversionserver-suchasMicrosoft'sWINSserver
Serverhardware
Mostserversusecomponentredundancytechnology,RAIDtechnology,memoryerrorcorrectiontechnologyandmanagementsoftware.High-endserversusemulti-processorsandsupportasymmetricalprocessorstructurewithmorethandualCPUs.Whenselectingserverhardware,inadditiontoconsideringthegradeandspecificfunctionpositioning,youalsoneedtofocusonunderstandingthemainparametersandcharacteristicsoftheserver,includingprocessorarchitecture,scalability,serverstructure,I/0capabilities,andfailurerecoverycapabilities.Servertypescanbedividedaccordingtomultiplestandards.
1.Dividedaccordingtoapplicationlevelorscale
● Entry-levelserver: infimus-endserver, maxime usus est forofficefile andprintingservices.
● Workgroup-dispensator: apta formas-scalenetworks, apta ad providendum Web, mailando alia officia forsmallandmedium-sizedenterprises.
●Departmentariis:mediis-servatoribus,formedium-sizedenterprisedatacentibus idoneum, Websitesandotherapplicationes.
● Enterprise-classer: High-server, withsuperdataprocessingcapabilities, idonea forlarge-scalenetworkdatabaseservatori.
2.Dividedaccordingtotheserverstructure
●Desktopserver:alsoknownastowerserver,thisisthemosttraditionalstructurewithbetterexpansionsex.
● inchcabinet-escendens: Therack-ascendens-inchcabinet-serveris installedinastandard19-inchcabinet.
● Bladeserver:Itisahigh-availability, high-density, low-costserverplatformdesigned forspecialapplicationindustries and high-densitycomputerenvironments.Each"blade" isactuallyasystemmotherboard.
scrinium typeserver: Thechassisisacabinet type, andaloofmodulecomponents need tobe installed in the server.
3.Dividedaccordingtohardwaretype
●Dedicatedserver:aspeciallydesignedhigh-levelserverwithaspecialoperatingsystem(suchasUNIX,MVS,VMS,etc.)),whichismainlyusedfordatabaseservicesandInternetbusiness.Generally,professionalcompaniesprovideafullsetofsoftwareandhardwaresystemsandfullservice.
●PCserver:AserverwithIntelorMotoroladedicatedprocessorsasthecore,compatiblewithavarietyofnetworkoperatingsystemsandnetworkapplicationsoftware,anditsperformancecanreachthelevelofmid-rangeRISCservers.
Wordmeaingdiscrimination
Sometimes,wewillseeanotherconceptofwebserverwhichisdifferentfromwebserver.Thesetwodefinitionscancauseconfusion.Theformerreferstothecomputerusedforthewebsite,andthelatterreferstotheprogramthatincludessoftwaresuchasApache,whichrunsonacomputertomanagewebpagecomponentsandrespondtowebbrowserrequests.
Safetymeasures
(1)Makeabackupoftheserversystemfortimelyrestoration.
(2)Closeunnecessaryserviceportsandonlyopentherequiredports.
(3)Securitycheckforabnormalprocess,installandupdateserveroperatingsystemintime.
(4) Installsoftwarefirewallandanti-virussoftwareinthesystem.
(5)Openthelogservicetocheckthewhereaboutsofhackers.
(6)Implementationofencryptionandauthenticationsecuritytechnology.
Indirectinfluence
Themajorsearchenginesarechoosingsomewebsiteswithbetteruserexperiencetomakebetterrankings.ThePVvalueofthewebsitedirectlyaffectstherankingofthewebsite.So,ifyouchooseaproductfromsuchahigh-qualityserverrenter,everyvisitorwillvisityourwebsiteataveryfastspeed,andthenaturalPVvaluewillbehigh.Thentheexperienceonyourwebsitewillnaturallybebetter.Ifeveryvisitorislikethis,thefriendlinessofthesearchenginewillgraduallyimprove.Thennaturallygivebetterweight.Therefore,high-qualitynetworkhostingspaceisthebasisforimprovingcustomerexperience.