HTTP – HyperText Transfer Protocol.ppt

HTTP HyperTextTransferProtocol HTMLforms htmlformsareusefullforgettingdifferentkindsofuserinputandsendingthisinputtothewebserverhtmlformsareintroducedbythetagsyntaxof textcontent inputelements inputelementsaredescribedusingthetag attributes action URL specifieswheretheform datawillbesentwhentheformissubmittedaccept MIMEtype specifiesthetypesoffilesthatcanbesubmittedthroughafileuploadaccept charset charset specifiesthecharacter settheserercanhandleforform dataenctype application x www form urlencoded multipart form data text plain specifieshowformdatashouldbeencodedbeforesendingittothewebservermethod get form dataissenttothewebserverintheheaderoftheHTTPrequest post form dataissenttothewebserverinthebodyoftheHTTPrequest specifieshowtosendform dataname string thenameoftheform Typesofuserinput Thetag isusefulforselectinguserinformationreceivesinputinvarioustypeshasnoendtaginHtmlattributes accept MIME type fortype file onlyspecifiestypesoffilesthatcanbesubmittedthroughafileuploadalt text fortype image onlyspecifiesanalternatetextforanimageinputchecked checked fortype checkbox radio specifiesiftheinputshouldbepreselectedwhenthepageloadsdisabled disabled specifiestheinputshouldbedisabledwhenthepageloadsmaxlength number fortype text password specifiesthemaximumlengthincharactersoftheinputfieldname text specifiesthenameofinputelementreadonly readonly fortype text password specifiestheinputfieldshouldberead onlysize number thewidthoftheinputfieldsrc URL theURLofanimagetodisplayasasubmitbuttontype button checkbox file hidden image password radio reset submit textvalue text valueoftheinputelement Othertagsusefulins definesamulti linetextinputcontrolcanholdanunlimitedno ofcharacterstextisrenderedinfixed widthfont usuallycourier attributes cols number visiblenumberofcolumnsinatextarea requiredattribute rows number visiblenumbersofrowsinatextarea requiredattribute disabled disabled textareaisdisabledreadonly readonly textareaisreadonlyname text nameofthetextareaelementEx Thisisatextarea and doesnotrenderanything definesalabelforaninputelement ittogglesthecontroliftheuserclicksthetextwithinthelabeldefinesapushbutton itcancontaininsidetextorimages differencefrom attributesfor disabled disabled buttonisdisabledname text nameofthebuttontype button reset submit typeofthebuttonvalue text valueofthebuttonEx Clickme and definesacaptionforaelementgroupstogetherformelements itdrawsaboxaroundthemEx SomecaptiongroupstogetherrelatedoptionsinaselectlistEx AppleGrapesFootballBasketball and andareusefulforcreatingadrop downlistEx FordFerrariBMWattributesofselect disabled disabled listisdisabledmultiple multiple multipleselectionsarepossiblename text nameoftheelementsize number no ofvisibleoptionsinthelistattributesofoption disabled disabled thisoptionisdisabledselected selected thisoptionisselectedbydefaultvalue text valuethatwillbesenttotheserverwhentheformissubmitted SetsofcharactersinHTML Mostbrowserssupport ASCIIcharacterset see see URL UniformResourceLocator anURLidentifiesaresourceintheWWWURLsareasubsetofURIs UniformResourceIdentifiers URL URIthatprovidesthelocationforaresourcegeneralformofaURL resource type domain port filepathname querystring anchorresource type theschemename protocol whichdefinesthenamespace syntaxandremainingpartofURLdomain registereddomainnameorIPaddressoflocation case insensitive port portnumber optional defaultforschemeisused filepathname pathtotheresource fileontheserver usuallycase sensitive querystring datasubmittedtotheserverthroughformsanchor aspecificlocationinsidethatdocument URLexamples ftp URI UniformResourceIdentifier Webcommunication Internet Get HTTPReply Client browser Firefox onlocalcomputer Webserver HTTP HyperTextTransferProtocol togetherwithHTMLformsthebaseofWWWisstandardizedbyIETF rfc2616 isarequest responseprotocolitisstateless doesnotmaintainastateofasession andasynchronous anhtmldocumentisloadedasynchronousbythebrowser assoonaspartsofitareavailable latestversionisHTTP 1 1runsontopofTCPonthestandardizedport80 HTTPRequest hastheform Request MethodSPRequest URLSPHTTP Version generic header request header entity header messagebody Request Methodis GET requestwhateverinformationisidentifiedbytheRequest URLPOST requestthatserveracceptstheentityenclosedintherequestOPTIONS requestforinformationaboutcommunicationoptionsPUT requestthattheenclosedentitybestoredundertheRequest URLDELETE requestthattheserverdeletetheresourceidentifiedbyRequest URLTRACE invokearemote application layerloopbackoftherequestmessageCONNECT usedbyproxiesinSSLconnectionsHEAD identicaltoGET butservermustnotreturnamessagebodyinresponse HTTPRequest 2 Request headercanhavethefollowingfields selection Accept MIMEtypesofresourcesacceptedbybrowserAccept Charset charsetacceptedbybrowserAccept Encoding encodingacceptedbybrowserAccept Language languageacceptedbybrowserAuthorization user agentwishestoauthenticateitselfwithaserverHost thehostRequest URLpointstoReferer theURLofdocumentreferingthisURLUser Agent Firefox Safari IE HTTPResponse hastheform Http VersionSPStatus CodeSPReason Phrase generic header response header entity header messagebody Response headerhasthefollowingfields selection Accept Ranges serverindicatesitsacceptanceofrangerequestsforresourceAge sender sestimateoftheamountoftimesincetheresponsewasgeneratedbyserverLocation redirecttheclienttoalocationotherthanRequest URLforcompletionoftherequestRetry After indicatetoclienthowlongtheserviceisexpectedtobeunavailableServer informationaboutsoftwareusedbytheservertohandletherequest HTTPRequestexample GetHTTP 1 1Host User Agent Mozilla 5 0 Windows U WindowsNT5 1 en US rv 1 9 1 3 Gecko 20090824Firefox 3 5 3 NETCLR3 5 30729 Accept text html application xhtml xml application xml q 0 9 q 0 8Accept Langu