Network Server

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)""Instantcreation,instantdestructionstrategy"",thatis,theserverConnectwitheachrequestingclient,andcreateasub-processforeachclient'srequesttoprocess.

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)Theservercreatesmultiplechildprocessesinadvance,andthechildprocessesprocessclientrequests.Thismethodiscalled"pre-creation".

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-suchasOracledatabaseserver,MySQL,PostgreSQL,MicrosoftSQLServer,etc.

Network Server

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:Thelowest-endserver,mainlyusedforofficefileandprintingservices.

●Workgroup-levelserver:suitableforsmall-scalenetworks,suitableforprovidingWeb,mailandotherservicesforsmallandmedium-sizedenterprises.

●Department-levelservers:mid-rangeservers,suitableformedium-sizedenterprisedatacenters,Websitesandotherapplications.

●Enterprise-classserver:High-endserver,withsuperdataprocessingcapabilities,suitableforlarge-scalenetworkdatabaseserver.

2.Dividedaccordingtotheserverstructure

●Desktopserver:alsoknownastowerserver,thisisthemosttraditionalstructurewithbetterexpansionsex.

●Rack-mountedserver:Therack-mountedserverisinstalledinastandard19-inchcabinet.Accordingtotheheight,thereare1U(1U=1.75inches),2U,4U,and6Uspecifications.

●Bladeserver:Itisahigh-availability,high-density,low-costserverplatformdesignedforspecialapplicationindustriesandhigh-densitycomputerenvironments.Each"blade"isactuallyasystemmotherboard.

●Cabinet-typeserver:Thechassisisacabinet-type,andalotofmodulecomponentsneedtobeinstalledintheserver.

3.Dividedaccordingtohardwaretype

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

●PCserver:AserverwithIntelorMotoroladedicatedprocessorsasthecore,compatiblewithavarietyofnetworkoperatingsystemsandnetworkapplicationsoftware,anditsperformancecanreachthelevelofmid-rangeRISCservers.

Wordmeaningdiscrimination

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.

Related Articles
TOP