Definice
Virtualhosting,alsocalled"websitespace",istodivideaphysicalserverrunningontheInternetintomultiple"virtual"servers.Virtualhosttechnologyhasgreatlypromotedtheapplicationandpopularizationofnetworktechnology.Atthesametime,therentalserviceofvirtualhostshasbecomeaneweconomicformintheInternetage.
Pozadí
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.
Technické vlastnosti
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".
Výhody
Nízké náklady
Comparedwiththepurchaseofanindependentserver,thecostofwebsiteconstructionisgreatlyreduced,whichprovidesgreatconvenienceforthepopularizationofsmallandmedium-sizedwebsites.
Thevirtualhostsarecompletelyindependent.Fromtheoutsideworld,eachvirtualhostisexactlythesameasanindependenthost.Sincemultiplevirtualhostssharetheresourcesofarealhost,thehardwarecosts,networkmaintenancecosts,andcommunicationlinecoststhateachvirtualhostuserbearsaregreatlyreduced.
Manycompaniesusethismethodtobuildwebsites,whichnotonlygreatlysavesthecostofbuyingmachinesandrentingdedicatedlines,butalsothewebsiteservermanagementissimple.Securitymeasuressuchassoftwareconfiguration,anti-virus,andanti-attackarealldonebyprofessionalTheserviceproviderprovides,whichgreatlysimplifiesthecomplexityofservermanagement;atthesametime,thereisnoneedtoworryaboutthetechnicalproblemsofusingandmaintainingtheserver,andthereisnoneedtohirespecializedmanagementpersonnel.
Zlepšení účinnosti
Intheinitialstageofwebsiteconstruction,ittakesalongtimetoinstalltheoperatingsystemandapplicationsoftwarefromthepurchaseofaserver,whilerentingavirtualhostusuallyonlytakesafewminutestoactivate.Becausethemajorregistereddomainnamequeryserviceprovidershaverealizedthee-commerceoftheentirebusinessprocess,chooseavirtualhostthatsuitsyourneeds,andyoucanopenitimmediatelyafteronlinepayment.
TheemergenceofvirtualhosttechnologyisamajorcontributiontothedevelopmentofInternettechnologyandnetwork.Sincemultiplevirtualhostssharetheresourcesofarealhost,theutilizationrateofserversandcommunicationlinesisgreatlyincreased,makingoneMultiplenetworkIPaddressescanbeconfiguredonaserverwithoutconflict,whichmeansthatpeoplecanusevirtualhoststobuildseveralsiteswithseparatedomainnamesononeserver,insteadofhavingtopurchaseseparatesitestobuildasite.Serversanddedicatedlinesforapplicationwithhugesumsofmoneyareusedasnetworkinformationoutlets.
Nevýhody
Funkční omezení
Somefunctionsarerestrictedbyserviceproviders,suchasforumprogramsthatmayconsumesystemresources,trafficstatisticsfunctions,etc.Websitedesignneedstoconsiderthefunctionalsupportprovidedbytheserviceprovider,suchasdatabasetype,operatingsystem,etc.Generally,virtualhostsdonothaveaseparateIPaddressinordertoreducecosts,thatis,IPaddressescannotdirectlyaccesswebsites(becausetherearemultiplewebsitescorrespondingtothesameIPaddress)
Rychlost přístupu a omezení provozu
Differentvirtualhostsonaserverareindependentandmanagedbyusers.However,aserverhostcanonlysupportacertainnumberofvirtualhosts.Whenthisnumberisexceeded,userswillexperienceasharpdropinperformance.
Theaccessspeedofsomevirtualhostwebsitesistooslow.Thismaybecausedbythehostingproviderrentingahosttoalargenumberofwebsites,orserverconfigurationandotherreasons.ThissituationwebsiteIfyoucan’tsolveitbyyourself,itwillhaveanadverseeffectonthenormalvisitofthewebsite;
Someserviceprovidershavecertainrestrictionsonwebsitetraffic,sothatnormalvisitswillnotbepossiblewhenthewebsitehasalargeamountofvisits.
Špatná autonomie
Thevirtualhostcannotbeoperatedbythecustomertoinstallsoftwareandremotedesktopatwill.
Účel
Pohodlné řízení
Allvirtualhostsareinthesamehost,sotheycansharethesameconfigurationsettings,therebysavingmanagementmanpowerAndcost.
Zlepšit výkon
Virtualhostsinthesamehostcanshareeachother'sassembly(ProcessPool),sotheresponsetimetotheclientcanbeshortened.
Snižování nákladů
Virtualhostingallowstheresourcesofasingleservertobeusedmoreeffectively,includingmemory,storagespaceorprocessorresources.BecausetheresourcesrequiredtoserveasingleURLareusuallyquitesmallfortheentireserver,thisallowstheserver'sresourcestobeusedmoreeffectively.
Multiplevirtualserverscanbesetuponthesamephysicalserverthroughsoftware,andeachvirtualservercanprovideallthefunctionsoftheserver,sorelativelyspeaking,thecostofeachvirtualserverhasacertaindegreereduce.
Typ implementace
Existují tři hlavní metody implementace: korespondence s názvem URL (podle názvu), korespondence s IP adresou (na základě IP) a korespondence s číslem portu (podle portu).
Korespondence s názvem URL (na základě názvu)
Korespondence s názvem URL (na základě názvu)istodeterminethecorrespondingservicebyidentifyingtheURLprovidedbytheclient.ThismethodEffectivelyreducetheoccupationoftheIPaddress,butthedisadvantageisthatitmustrelyonthesupportoftheDNSnamemappingservice.Ifthenamemappingserviceisinterrupted,theservicecorrespondingtothenamewillalsobeunavailable.
Korespondence IP adresy (na základě IP)
Korespondence IP adresy (na základě IP)referstothesameserver,throughthesameconfigurationsettings,differentIPtomanageMultipleservices.
Korespondence založená na portu (na základě portu)
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.
Vyberte virtuálního hostitele
Hardwarové vybavení hostitele
WhatthevirtualhostproviderownsThevirtualhostcomputerroom,whatsizedatacenterisit,whetherthereisenoughbandwidthforthecomputerroomline,andwhetherthespeedofthevirtualhostwebsiteconnectionmeetsthetrafficbandwidthofallhisvirtualhostcustomersatthesametime.
Kolik webových stránek je nastaveno na virtuálním hostiteli
Usuallyavirtualhostcanhosthundredstothousandsofwebsites,ifThemorewebsitesthereare,themorepeoplesharethesameserver;incomparison,resourcesaretighter.Generallyrelatedtothemachine'sCPU,memory,etc.IISisgenerally10000/numberofconnectionsperserver.