Virtual host

Definition

Virtualhosting,alsocalled"websitespace",istodivideaphysicalserverrunningontheInternetintomultiple"virtual"servers.Virtualhosttechnologyhasgreatlypromotedtheapplicationandpopularizationofnetworktechnology.Atthesametime,therentalserviceofvirtualhostshasbecomeaneweconomicformintheInternetage.

Background

Therearenearly100millioncomputersinterconnectedontheInternet.Nomatterwhattypeofcomputertheyare,whatoperatingsystemtheyrun,andwhatsoftwaretheyuse,theycanbeclassifiedintotwocategories:customersMachinesandservers.

  • Client:Theclientisamachinethataccessesotherhosts.WhenaccessingtheInternetthroughanISP(InternetServiceProvider),theclientisassignedatemporaryIPaddress.UsingthistemporaryIPaddress,theclientcanobtaininformationontheInternet.Afterthenetworkisdisconnected,theclientThemachinewasseparatedfromtheInternet,andtheIPaddresswastakenback.

  • Server:Aserverisacomputerthathashighcomputingpowerandcanbeusedbymultipleusers.Itisusuallycalledahost.Therearemanydifferencesbetweentheserverandtheclient.Forexample,theclientusuallyonlyservesoneuseratatime.Theclientisusedbytheuserthroughtheterminal,andtheserverisusedbytheclientuserthroughthenetwork.Comparedwiththeclient,theserverneedstoworkcontinuouslyinanenvironmentof7×24hours.ThismeansthattheserverneedsmorestabilitytechnologyRAS(Reliability,AvailabilityandServiceability,reliability,availability,applicability),suchassupportingtheuseofECC(ErrorCheckandCorrection)memory.

Technicalfeatures

VirtualhostingtechnologyisatechnologyusedbyInternetserverstosaveserverhardwarecosts.VirtualhostingtechnologyismainlyusedinHTTP(HypertextTransferProtocol).,HypertextTransferProtocol)service,whichlogicallydividesacertainoralloftheservicecontentofaserverintomultipleserviceunits,whichareexternallyrepresentedasmultipleservers,soastomakefulluseofserverhardwareresources.

Virtualhostusesspecialsoftwareandhardwaretechnologytodividearealphysicalserverhostintomultiplelogicalstorageunits.Eachlogicalunithasnophysicalentity,buteachlogicalunitcanworkonthenetworklikearealphysicalhost,withaseparateIPaddress(orsharedIPaddress),anindependentdomainname,andacompleteInternetserver(supportWWW,FTP,E-mail,etc.)functions.

Thekeytechnologyofvirtualhostingisthatevenifdifferentserverprogramsopenedformultipleusersarerunningonthesamehardwareandthesameoperatingsystem,theydonotinterferewitheachother.Eachuserhashisownpartofthesystemresources(IPaddress,documentstoragespace,memory,CPU,etc.).Eachvirtualhostiscompletelyindependent.Fromtheoutside,eachvirtualhostandasinglehostbehaveexactlythesame.Therefore,thisvirtualizedlogicalhostisvividlycalleda"virtualhost".

Advantages

Lowcost

Comparedwiththepurchaseofanindependentserver,thecostofwebsiteconstructionisgreatlyreduced,whichprovidesgreatconvenienceforthepopularizationofsmallandmedium-sizedwebsites.

Thevirtualhostsarecompletelyindependent.Fromtheoutsideworld,eachvirtualhostisexactlythesameasanindependenthost.Sincemultiplevirtualhostssharetheresourcesofarealhost,thehardwarecosts,networkmaintenancecosts,andcommunicationlinecoststhateachvirtualhostuserbearsaregreatlyreduced.

Manycompaniesusethismethodtobuildwebsites,whichnotonlygreatlysavesthecostofbuyingmachinesandrentingdedicatedlines,butalsothewebsiteservermanagementissimple.Securitymeasuressuchassoftwareconfiguration,anti-virus,andanti-attackarealldonebyprofessionalTheserviceproviderprovides,whichgreatlysimplifiesthecomplexityofservermanagement;atthesametime,thereisnoneedtoworryaboutthetechnicalproblemsofusingandmaintainingtheserver,andthereisnoneedtohirespecializedmanagementpersonnel.

Improveefficiency

Intheinitialstageofwebsiteconstruction,ittakesalongtimetoinstalltheoperatingsystemandapplicationsoftwarefromthepurchaseofaserver,whilerentingavirtualhostusuallyonlytakesafewminutestoactivate.Becausethemajorregistereddomainnamequeryserviceprovidershaverealizedthee-commerceoftheentirebusinessprocess,chooseavirtualhostthatsuitsyourneeds,andyoucanopenitimmediatelyafteronlinepayment.

TheemergenceofvirtualhosttechnologyisamajorcontributiontothedevelopmentofInternettechnologyandnetwork.Sincemultiplevirtualhostssharetheresourcesofarealhost,theutilizationrateofserversandcommunicationlinesisgreatlyincreased,makingoneMultiplenetworkIPaddressescanbeconfiguredonaserverwithoutconflict,whichmeansthatpeoplecanusevirtualhoststobuildseveralsiteswithseparatedomainnamesononeserver,insteadofhavingtopurchaseseparatesitestobuildasite.Serversanddedicatedlinesforapplicationwithhugesumsofmoneyareusedasnetworkinformationoutlets.

Disadvantages

Functionlimitations

Somefunctionsarerestrictedbyserviceproviders,suchasforumprogramsthatmayconsumesystemresources,trafficstatisticsfunctions,etc.Websitedesignneedstoconsiderthefunctionalsupportprovidedbytheserviceprovider,suchasdatabasetype,operatingsystem,etc.Generally,virtualhostsdonothaveaseparateIPaddressinordertoreducecosts,thatis,IPaddressescannotdirectlyaccesswebsites(becausetherearemultiplewebsitescorrespondingtothesameIPaddress)

Accessspeedandtrafficlimit

Differentvirtualhostsonaserverareindependentandmanagedbyusers.However,aserverhostcanonlysupportacertainnumberofvirtualhosts.Whenthisnumberisexceeded,userswillexperienceasharpdropinperformance.

Theaccessspeedofsomevirtualhostwebsitesistooslow.Thismaybecausedbythehostingproviderrentingahosttoalargenumberofwebsites,orserverconfigurationandotherreasons.ThissituationwebsiteIfyoucan’tsolveitbyyourself,itwillhaveanadverseeffectonthenormalvisitofthewebsite;

Someserviceprovidershavecertainrestrictionsonwebsitetraffic,sothatnormalvisitswillnotbepossiblewhenthewebsitehasalargeamountofvisits.

Poorautonomy

Thevirtualhostcannotbeoperatedbythecustomertoinstallsoftwareandremotedesktopatwill.

Purpose

Convenientmanagement

Allvirtualhostsareinthesamehost,sotheycansharethesameconfigurationsettings,therebysavingmanagementmanpowerAndcost.

Improveperformance

Virtualhostsinthesamehostcanshareeachother'sassembly(ProcessPool),sotheresponsetimetotheclientcanbeshortened.

Costreduction

Virtualhostingallowstheresourcesofasingleservertobeusedmoreeffectively,includingmemory,storagespaceorprocessorresources.BecausetheresourcesrequiredtoserveasingleURLareusuallyquitesmallfortheentireserver,thisallowstheserver'sresourcestobeusedmoreeffectively.

Multiplevirtualserverscanbesetuponthesamephysicalserverthroughsoftware,andeachvirtualservercanprovideallthefunctionsoftheserver,sorelativelyspeaking,thecostofeachvirtualserverhasacertaindegreereduce.

Implementationtype

Therearethreemainimplementationmethods:URLnamecorrespondence(Name-based),IPaddresscorrespondence(IP-based)andPortportnumbercorrespondence(Port-based).

URLnamecorrespondence(Name-based)

URLnamecorrespondence(Name-based)istodeterminethecorrespondingservicebyidentifyingtheURLprovidedbytheclient.ThismethodEffectivelyreducetheoccupationoftheIPaddress,butthedisadvantageisthatitmustrelyonthesupportoftheDNSnamemappingservice.Ifthenamemappingserviceisinterrupted,theservicecorrespondingtothenamewillalsobeunavailable.

IPaddresscorrespondence(IP-based)

IPaddresscorrespondence(IP-based)referstothesameserver,throughthesameconfigurationsettings,differentIPtomanageMultipleservices.

Port-basedcorrespondence(Port-based)

ItissimilartoIPaddresscorrespondence,butunderthesameIP,differentPortportnumbersareusedtodistinguishdifferentservices.Inordertoquicklycreatemultiplevirtualhosts.Forexample:

  • 192.168.0.1:80

  • 192.168.0.1:8080

  • 192.168.0.1:8888

However,mostoftheseapplicationsareusedinprivateorexperimentalservicesbecauseuserscannotusethedefaultportnumber(forexampleThedefaultportnumberofthewebserviceis80)tousetheprovidedservice,unlesstheuserknowstheportnumberforprovidingtheservice.

Chooseavirtualhost

  • Thehardwarefacilitiesofthehost

  • WhatthevirtualhostproviderownsThevirtualhostcomputerroom,whatsizedatacenterisit,whetherthereisenoughbandwidthforthecomputerroomline,andwhetherthespeedofthevirtualhostwebsiteconnectionmeetsthetrafficbandwidthofallhisvirtualhostcustomersatthesametime.

  • Howmanywebsitesaresetuponthevirtualhost

  • Usuallyavirtualhostcanhosthundredstothousandsofwebsites,ifThemorewebsitesthereare,themorepeoplesharethesameserver;incomparison,resourcesaretighter.Generallyrelatedtothemachine'sCPU,memory,etc.IISisgenerally10000/numberofconnectionsperserver.

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