邪修魔法師約8020字最新章節無彈窗 全文無廣告免費閱讀 憤怒的影子

thehttpmethodssuchasgetandpostaretheverbsthatthedevelopercanusetodescribethenecessary，read，，and（crud）actionstobeperformed.somemayseeananalogytooperationsinsql，whichalsoreliesonafewcommonverbs，asnintable1.however，thereststyleandhttpprotocolaremutuallyexclusive，andrestdoesnotrequirehttp.

table1：relationshipsbetweensqlandhttpverbs

actionsqlhttp

putreadgetpost

whentouserest

architectsanddevelopersneedtodecidewhenthisparticularstyleisanappropriatechoicefortheirapplications.arestfuldesignmaybeappropriatewhen

thewebservicesarecompletelystateless.agoodtestistoconsiderwhethertheinteractioncansurvivearestartoftheserver.

acachinginfrastructurecanbeleveragedforperformance.ifthedatathatthewebservicereturnsisnotdynamicallygeneratedandcanbecached，thenthecachinginfrastructurethatwebserversandotherintermediariesinherentlyprovidecanbeleveragedtoimproveperformance.however，thedevelopermusttakecarebecausesuchcachesarelimitedtothehttpgetmethodformostservers.

theserviceproducerandserviceconsumerhaveamutualunderstandingofthecontextandcontentbeingpassedalong.becausethereisnoformalwaytodescribethewebservicesinterface，bothpartiesmustagreeoutofbandontheschemasthatdescribethedatabeingexchangedandonwaystoprocessitmeaningfully.intherealworld，mostcommercialapplicationsthatexposeservicesasrestfulimplementationsalsodistributeso-calledvalue-addedtoolkitsthatdescribetheinterfacestodevelopersinpopularprogramminglanguages.

bandwidthisparticularlyimportantandneedstobelimited.restisparticularlyusefulforlimited-profiledevicessuchaspdasandmobilephones，forwhichtheoverheadofheadersandadditionallayersofsoapelementsonthexmlpayloadmustberestricted.

webservicedeliveryoraggregationintoexistingwebsitescanbeenabledeasilywitharestfulstyle.developerscanusetechnologiessuchasasynchronousjavascriptwithxml（ajax）andtoolkitssuchasdirectwebremoting（dwr）toconsumetheservicesintheirwebapplications.ratherthanstartingfromscratch，servicescanbeexposedwithxmlandconsumedbyhtmlpageswithoutsignificantlyrefactoringtheexistingwebsitearchitecture.existingdeveloperswillbemoreproductivebecausetheyareaddingtosomethingtheyarealreadyfamiliarwith，ratherthanhavingtostartfromscratchwithnewtechnology.

asoap-baseddesignmaybeappropriatewhen

aformalcontractmustbeestablishedtodescribetheinterfacethatthewebserviceoffers.thewebservicesdescriptionlanguage（wsdl）describesthedetailssuchasmessages，operations，bindings，andlocationofthewebservice.

thearchitecturemustaddresscomplexnonfunctionalrequirements.manywebservicesspecificationsaddresssuchrequirementsandestablishacommonvocabularyforthem.examplesincludetransactions，security，addressing，trust，coordination，andsoon.mostreal-worldapplicationsgobeyondsimplecrudoperationsandrequirecontextualinformationandconversationalstatetobemaintained.withtherestfulapproach，developersmustbuildthisplumbingintotheapplicationlayerthemselves.

thearchitectureneedstohandleasynchronousprocessingandinvocation.insuchcases，theinfrastructureprovidedbystandardssuchaswsrmandapissuchasjax-wswiththeirclient-sideasynchronousinvocationsupportcanbeleveragedoutofthebox.

restfulsupportinjax-ws

thejavaapiforxmlwebservices（jax-ws）providesfullsupportforbuildinganddeployingrestfulwebservices.theapiwasdevelopedthroughthejavacommunityprocessprogramasjsr224.itistightlyintegratedwiththejavaarchitectureforxmlbinding（jaxb）forbindingxmltojavatechnologydataandisincludedinboththejavaplatform，standardedition（javase）6andthejavaplatform，enterpriseedition（javaee）5.

buildingrestfulservices

theexampleusedinthissectionbuildsonthepurchaseorderservicedescribedinthejavaeeblueprintscatalogasthe"patternsanddesign"whitepapers（parts1，2，and3）.theoriginalendpointcontainedonlyonemethod--acceptpo--thatacceptedapurchaseorderandreturnedapurchaseorderstatus，bothofwhichweredefinedbyindividualschemas.

table2ssomemorecrudoperationstoaddtothisservice.

table2：additionalcrudoperations

descriptionjavatechnologymethodsignature

aneworderpublicpurchaseorderstatusacceptpo（purchaseorderorder）

retrieveanexistingorderpublicpurchaseorderretrievepo（stringorderid）

modifyanexistingorderpublicpurchaseorderpo（purchaseorderorder）

cancelanorderalreadysubmittedpublicvoidcancelpo（stringorderid）

jax-wsenablesbuildingrestfulendpointsthroughajavax.xml.ws.providerinterfaceintheapi.providerisagenericinterfacethatcanbeimplementedbyaclassasadynamicnativetoaserviceendpointinterface（sei），andaserviceimplementingthisinterfacecanbedeployedinajavaeecontainerorpublishedinastand-alonemodethroughthejax-wsendpointapi.theproviderinterfacecontainsasinglemethodwiththefollowingsignature：

tinvoke（trequest）

providerisalow-levelgenericapi，butusingitrequirestheendpointtohaveanintimateknowledgeofthedesiredmessageorpayloadstructurebeingpassedtotheservice.dependingonhowtheproviderisimplemented，thesupportedtypesfortandtheirusesarethefollowing：

☆、第四十八章 治好達兒的病

insoftwareengineering，thetermsoftwarearchitecturalstylegenerallyrefersto"asetofdesignrulesthatidentifythekindsofcomponentsandconnectorsthatmaybeusedtocomposeasystemorsubsystem."*somecommonexamplesofarchitecturalstylesincludethepipeandfilter，layered，pushbased，andsoon.inthewebservicesworld，representationalstatetransfer（rest）isakeydesignidiomthatembracesastatelessclient-serverarchitectureinwhichthewebservicesareviewedasresourcesandcanbeidentifiedbytheirurls.webserviceclientsthatwanttousetheseresourcesaccessaparticularrepresentationbytransferringapplicationcontentusingasmallgloballydefinedsetofremotemethodsthatdescribetheactiontobeperformedontheresource.restisananalyticaldescriptionoftheexistingwebarchitecture，andthustheinterplaybetweenthestyleandtheunderlyinghttpprotocolappearsseamless.

thehttpmethodssuchasgetandpostaretheverbsthatthedevelopercanusetodescribethenecessary，read，，and（crud）actionstobeperformed.somemayseeananalogytooperationsinsql，whichalsoreliesonafewcommonverbs，asnintable1.however，thereststyleandhttpprotocolaremutuallyexclusive，andrestdoesnotrequirehttp.

table1：relationshipsbetweensqlandhttpverbs

actionsqlhttp

putreadgetpost

whentouserest

architectsanddevelopersneedtodecidewhenthisparticularstyleisanappropriatechoicefortheirapplications.arestfuldesignmaybeappropriatewhen

thewebservicesarecompletelystateless.agoodtestistoconsiderwhethertheinteractioncansurvivearestartoftheserver.

acachinginfrastructurecanbeleveragedforperformance.ifthedatathatthewebservicereturnsisnotdynamicallygeneratedandcanbecached，thenthecachinginfrastructurethatwebserversandotherintermediariesinherentlyprovidecanbeleveragedtoimproveperformance.however，thedevelopermusttakecarebecausesuchcachesarelimitedtothehttpgetmethodformostservers.

theserviceproducerandserviceconsumerhaveamutualunderstandingofthecontextandcontentbeingpassedalong.becausethereisnoformalwaytodescribethewebservicesinterface，bothpartiesmustagreeoutofbandontheschemasthatdescribethedatabeingexchangedandonwaystoprocessitmeaningfully.intherealworld，mostcommercialapplicationsthatexposeservicesasrestfulimplementationsalsodistributeso-calledvalue-addedtoolkitsthatdescribetheinterfacestodevelopersinpopularprogramminglanguages.

bandwidthisparticularlyimportantandneedstobelimited.restisparticularlyusefulforlimited-profiledevicessuchaspdasandmobilephones，forwhichtheoverheadofheadersandadditionallayersofsoapelementsonthexmlpayloadmustberestricted.

webservicedeliveryoraggregationintoexistingwebsitescanbeenabledeasilywitharestfulstyle.developerscanusetechnologiessuchasasynchronousjavascriptwithxml（ajax）andtoolkitssuchasdirectwebremoting（dwr）toconsumetheservicesintheirwebapplications.ratherthanstartingfromscratch，servicescanbeexposedwithxmlandconsumedbyhtmlpageswithoutsignificantlyrefactoringtheexistingwebsitearchitecture.existingdeveloperswillbemoreproductivebecausetheyareaddingtosomethingtheyarealreadyfamiliarwith，ratherthanhavingtostartfromscratchwithnewtechnology.

asoap-baseddesignmaybeappropriatewhen

aformalcontractmustbeestablishedtodescribetheinterfacethatthewebserviceoffers.thewebservicesdescriptionlanguage（wsdl）describesthedetailssuchasmessages，operations，bindings，andlocationofthewebservice.

thearchitecturemustaddresscomplexnonfunctionalrequirements.manywebservicesspecificationsaddresssuchrequirementsandestablishacommonvocabularyforthem.examplesincludetransactions，security，addressing，trust，coordination，andsoon.mostreal-worldapplicationsgobeyondsimplecrudoperationsandrequirecontextualinformationandconversationalstatetobemaintained.withtherestfulapproach，developersmustbuildthisplumbingintotheapplicationlayerthemselves.

thearchitectureneedstohandleasynchronousprocessingandinvocation.insuchcases，theinfrastructureprovidedbystandardssuchaswsrmandapissuchasjax-wswiththeirclient-sideasynchronousinvocationsupportcanbeleveragedoutofthebox.

restfulsupportinjax-ws

thejavaapiforxmlwebservices（jax-ws）providesfullsupportforbuildinganddeployingrestfulwebservices.theapiwasdevelopedthroughthejavacommunityprocessprogramasjsr224.itistightlyintegratedwiththejavaarchitectureforxmlbinding（jaxb）forbindingxmltojavatechnologydataandisincludedinboththejavaplatform，standardedition（javase）6andthejavaplatform，enterpriseedition（javaee）5.

buildingrestfulservices

theexampleusedinthissectionbuildsonthepurchaseorderservicedescribedinthejavaeeblueprintscatalogasthe"patternsanddesign"whitepapers（parts1，2，and3）.theoriginalendpointcontainedonlyonemethod--acceptpo--thatacceptedapurchaseorderandreturnedapurchaseorderstatus，bothofwhichweredefinedbyindividualschemas.