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ŻŶӾ飺վҳŻ34ƽ
1HTTP
նûӦʱУ80%ظݡⲿʱҳеͼʽűFlashȡͨҳеԪؿԼHTTPĴҳٶȵĹؼ衣
ҳķʵǼҳôûһַܱҳݵķḻܴﵽӿӦʱĿأмHTTPͬʱֿܱҳݷḻļ
ϲļͨеĽűŵһļHTTPķԼذеCSSļһʽСűʽڲͬҳʹʱҪͬģܻ鷳㣬ҲҪΪҳܵҪһ
CSS SpritesǼͼЧеıͼŵһͼƬļУȻͨCSSbackground-imagebackground-positionʾͼƬIJ֣ͬ
ͼƬͼǰѶͼƬϵһͼƬСȻļСı䣬ǿԼHTTPͼƬͼֻͼƬɲҳǽһʱʹã絼ȷͼƬͿܻȽϷ׳ͬʱʹͼƬͼҲпɶԣ˲Ƽַ
ͼʹdata:URL schemeķͼݼҳСܻҳĴСͼŵʽɻ棩пԼHTTPͬʱֱҳļĴСͼڻûеõ֧֡
ҳHTTPҪһǸĽ״ηûȴʱҪķͬTenni TheurerIJBrowser Cahe Usage - Exposed!˵HTTPռȥ40%60%Ӧʱ䡣Щηվ˻øӿٵɣ
2DNSҴ
ϵͳDNSṩIPĶӦϵ绰ǵĵ绰Ĺϵһַwww.dudo.orgʱDNSͻ᷵ӦIPַDNSĹͬҲҪʱġһ·ظӦIPַỨ20120ʱ䡣ʲôֱDNSϡ
DNSҿԸҳܡֻҪһضĻַһûISPṩ̻߱ؾƣͬûʹõļϲ档DNSϢᱣڲϵͳDNSУWindowsϵͳDNS Client ServiceжڲϵͳԼĻ档ԼϼһܵϵͳӰ졣
Internet ExplorerĬ¶DNSҼ¼ĻʱΪ30ӣעеļֵΪDnsCacheTimeoutFirefoxDNSIJҼ¼ʱΪ1ӣļеѡΪnetwork.dnsCacheExpirationFasterfoxѡΪ1Сʱ
ͻеDNS涼ΪʱͲϵͳΪգDNSҵĴҳͬаҳURLͼƬűļʽFlashȰԼDNSҴ
ԼҳвصDNSҴԽʡӦʱ䣬ǼٲȴӦʱ䡣ҵָԭǰЩҳеݷֵָIJֽ֡ڼDNSҴͱֽϸ̶߳Ȳ֮Ȩˡ
3ת
תʹ301302ʵֵġһӦΪ301HTTPͷ
HTTP/1.1 301 Moved Permanently
Location: http://example.com/newuri
Content-Type: text/html
ûָLocationָURLͷļеϢһתжDZģݲֿΪաǵƣ301302ӦᱻһͷѡExpiresCache-Controlָ档<meat />Ԫصˢ±ǩJavaScriptҲʵURLתҪתʱõķʹñ3XXHTTP״̬룬ҪΪȷˡťȷʹá
Ҫסתήû顣ûHTMLĵмһתҳԪصʾΪHTMLļǰκļͼFlashȣᱻء
һ־ҳߺȴʮ˷ӦʱתڵURLбܣ/ȴԵʱ磬Ҫhttp://astrology.yahoo.com/astrology ʱʵϷصһ301תָhttp://astrology.yahoo.com/astrology/ עĩβбܣApacheпʹAlias mod_rewritethe DirectorySlash⡣
վ;վתܾõһҪվIJͬȻûIJͬͣ͡û˺ͣתʹתʵվлʮּҪĴҲࡣʹַڿ˵Խӳ̶ȣͬû顣һͬһ̨ʱʹAliasmod_rewriteʵ֡ΪIJͬתôͨʹAliasmod_rewirteCNAMEһһ֮ϵDNS¼
4ɻAJAX
AjaxἰһôӺ̨Ϣ첽ԶΪûķļʱԡǣʹAjaxܱ֤ûڵȴ첽JavaScriptXMLӦϻʱ䡣ںܶӦУûǷҪȴӦȡAjaxʹá磬һWebEmailͻУûȴAjaxطʼѯסһ㣬첽ζšʱҪ
ΪܣŻAjaxӦǺҪġAjxaܵĴʩҪķʹӦпɻԣۿԲ鿴Add an Expires or a Cache-Control HeaderļҲͬAjax
Gizpѹļ
DNSҴ
JavaScript
ת
ETags
һӣһWeb2.0Emailͻ˻ʹAjaxԶɶûַءûϴʹùEmail webӦóûжԵַκεģAjaxӦͨExpireCacke-Controlͷʵֻ棬ôͿֱӴһεĻжȡַˡ֪ʹûеĵַǷһµͨΪȡַAjax URLһϴα༭ʱʱʵ֣磬&t=11900241612ȡַϴغûб༭ʱͲ䣬ĻмشӶһHTTP̡ûĹַʱͻȷµURLͻӦƥ䣬ͻҪµַ
ʹAjxaӦǶ̬ɵģֻһûôҲӦñʹWeb2.0Ӧóӿݡ
5Ƴټ
ϸһҳԼЩҳʱȼصģЩݺͽṹԺټأ
̰onload¼ָ֣JavaScriptһѡ磬ʵϷźͶJavaScriptôԵȴԺأΪҳϵϷԪڳʼ֮ŷġزֵݣûֵ֮ݣʹ۵ֵͼҲƳټ
߿ԽʡĹYUI Image LoaderƳټ۵ֵͼƬYUI Get utilityǰJS CSSıݷԴFirebugNetѡһYahooҳ
Ŀվʵһʱͻá£ͨվܵķǣ֧JavaScript£ȥû飬Ҫ֤վûJavaScriptҲСȷҳټؽűʵϷźͶȸӻڵЧ
6Ԥ
Ԥغͺؿƺǡǡ෴ʵԤΪʵһĿꡣԤʱܻõҳݣͼʽͽűʹַûҪһҳʱҳеݴѾصˣ˿ԴƷٶȡ
ṩ˼Ԥط
أonload¼ʱֱӼضҳݡGoogle.comΪԿһspirit imageͼonloadмصġspirit imageͼgoogle.comҳDzҪģȴҳõ
أûIJиݵжûȥҳ沢ӦԤҳݡsearch.yahoo.comԿʱضҳݡ
ԤڵļأƹҳʱʹԤءҳ澭ƺûԹµҳ濴ܿᣬȴǰܳûľվ㽨Ļ棬վȴûκλݡڷվ֮ǰͼһֽij֡ľվĿʱվõͼĺͽű߷ٶȡ
7DOMԪ
һӵҳζҪظݣͬʱҲζJavaScriptDOMЧԽ統һ¼ʱ5005000DOMԪѭЧ϶Dzһġ
DOMԪصĴζҳпԲƳֻҪ滻ԪرǩͿԾIJ֡ҳ沼ʹñûнΪ˲ֶ<div>ԪأҲһʺϻǸеıǩԹʹá
YUI CSS utilitiesԸIJִgrids.cssʵ岼֣font.cssreset.cssƳĬϸʽṩһҳбǩĻᣬֻʱʹ<div>ΪлЧʹ
DOMԪֻҪFirebugĿ̨룺
document.getElementsByTagName('*').length
ôٸDOMԪǶأԶкܺñʹõҳ档Yahoo!ҳһݷdzҳ棬ֻʹ700ԪأHTMLǩ
8ҳ
ҳݻֳɲֿʹȵʵƽءDNSҴӰҪȷʹõ24֮䡣磬õHTMLݺͶ̬ݷwww.example.orgϣҳͼƬűCSS)ֱstatics1.example.orgstatics.example.orgϡ
Tenni TheurerPatty ChiдMaximizing Parallel Downloads in the Carpool LaneҵϢ
9ʹiframeС
ifrmaeԪؿڸĵвһµHTMLĵ˽iframeĹȻܸЧʹһҪ
<iframe>ŵ㣺
ػĵͼȵļ
Security sandbox
мؽű
<iframe>ȱ㣺
ʱΪգҲҪʱ
ֹҳ
û
10Ҫ404
HTTPʱǺܴģʹHTTPһûôӦ404ûҵҳ棩ȫûбҪģֻήûһô
Щվ404ӦҳΪDzҪ***ȻĽû鵫ͬҲ˷ѷԴݿȣָⲿJavaScriptӳⲢ404롣ȣּػƻмأͼڷص404ӦҵõIJֵJavaScriptִС
11ʹݷַ
ûվĽӽ̶ȻӰӦʱij̡վݷɢڲͬλõķϿԼӿٶȡӦЩʲôأ
վݵĵһҪ¼ܹվڷַСӦõıվṹܻһЩȽϸӵڷͬSession״̬ͺϲݿµȡҪûݷľ룬ЩܹDzɱġ
ҪסնûӦʱ80%90%ӦʱͼʽűFlashҳݡվܻƽӦóܹȽѵȣֲ̬ݻһ㡣ⲻӦʱ䣬Ҷݷַ˵ʵ֡
ݷַ磨Content Delivery NetworkCDNһϵзɢͬλϵWebɵģվݵĴٶȡûݵķҪǸݺûϵĿ̶ָġ磬ӵnetwork hoPSӦٶķᱻѡ
һЩ͵繫˾ӵԼCDNʹAkamai TechnologiesMirror Image Internet Limelight NetworksCDNɱȴdzߡڸոҵվ˵ûʹCDNijɱԤ㣬ĿûȺIJȫCDNʵֿӦˡYahoo˵תƵCDNϵվ̬ݽʡնû20%ϵӦʱ䡣ʹCDNһֻҪԼĴʵվٶȵķ
12ΪļͷָExpiresCache-Control
ݣ
ھ̬ݣļͷʱExpiresֵΪNever expireڣ
ڶ̬ݣʹǡCache-Controlļͷ
ҳԽԽḻζҳҪĽűʽͼƬFlashһηҳûζŽжεHTTPͨʹExpiresļͷͿʹݾлԡ˽ҳвҪHTTPExpiresļͷͼļӦеݶʹűʽFlashȡ
ʹʹûHTTPĴСʹԼӿҳٶȡWebHTTPӦʹExpiresļͷ߿ͻҪʱ䡣һϳʱExpiresļͷӦֱ2010415ղŹڡ
Expires: Thu, 15 Apr 2010 20:00:00 GMT
ʹõApacheʹExpiresDefault趨ԵǰڵĹʱ䡣ʹExpiresDefault趨ʱ10ڵļͷ
ExpiresDefault "access plus 10 years"
ҪмǣʹExpiresļͷҳݸıʱͱıݵļYahoo!˵ǾʹIJ裺ݵļмϰ汾ţyahoo_2.0.6.js
ʹExpiresļͷֻлûѾʹվŻáû״ηվʱԼHTTP˵ЧģΪĻǿյġַվܵĸĽҪǡԤ桱ʱҳĵƵʣԤ桱ѾҳеݣYahoo!һײǷеҳ75~85%СԤ桱ͨʹExpiresļͷ˻ݵҿûٴʹЩݣҪͨûһֽڵ
13Gzipѹļ
紫еHTTPӦʱͨǰ˻ƵõơȷնûĴṩߡԵȽĿ̶ȵȶվܾġǻӰӦʱ䡣ͨСHTTPӦĴСԽʡHTTPӦʱ䡣
HTTP/1.1ʼwebͻ˶Ĭ֧HTTPAccept-Encodingļͷѹʽ
Accept-Encoding: gzip, deflate
webļͷмĴ룬ͻԿͻгķʽѹӦݡWebѹʽͨӦļͷеContent-Encodingظ
Content-Encoding: gzip
GzipĿǰҲЧѹʽGNUĿͨRFC 1952ġеһѹʽdeflateʹ÷ΧЧҲѷɫ
GzipſԼ70%ӦģĿǰԼ90%ͨĻ֧gzipʽʹõApachegzipģúİ汾йأApache 1.3ʹmod_zipApache 2.xʹmoflate
ʹ⣺յĺʵʽյݻڲƥҺãžʽʹļڼ١ApacheģͨԶʵVaryӦļͷ״ij֡
ļѡҪgzipѹļ˿ѹļwebѹHTMLĵԽűʽѹͬҲֵ飬Ǻܶwebûܡʵϣѹκһı͵ӦXMLJSONֵõġͼPDFļѾѹԲٽgzipѹͼgizpѹЩļĻ˷CPUԴļĴС
GzipѹпܵļǼļûļ
14ETag
Entity tagsETagsʵǩwebжеݺͷеԭʼǷƥһֻƣʵ塱˵ġݡͼƬűʽȣETagΪʵ֤ṩһʹálast-modified dateϴα༭ʱ䣩ĻơEtagһʶݰ汾ŵΨһַΨһĸʽƾ˫ڡԭʼͨETagļͷӦָҳݵETag
HTTP/1.1 200 OK
Last-Modified: Tue, 12 Dec 2006 03:03:59 GMT
ETag: "10c24bc-4ab-457e1c1f"
Content-Length: 12195
ԺҪ֤һļʹIf-None-MatchļͷETagظԭʼУETagƥ䣬ͻ᷵һ304״̬룬ͽʡ12195ֽڵӦ GET /i/yahoo.gif HTTP/1.1
Host: us.yimg.com
If-Modified-Since: Tue, 12 Dec 2006 03:03:59 GMT
If-None-Match: "10c24bc-4ab-457e1c1f"
HTTP/1.1 304 Not Modified
ETagڣǸݿԱվڵķľΨһԵɵġһ̨ϻҳݺһ̨Ͻ֤ʱETagͻƥ䣬ʹ÷ʹվ˵ǷdzġĬ£ApacheIISǶETagУٶļ֤ͻ
Apache 1.32.xеETagʽΪinode-size-timestampʹijļڲͬķϻᴦͬĿ¼£ļСȨޡʱȶȫͬڲͬǵҲDzͬġ
IIS 5.0IIS 6.0ETagĻơIISеETagʽΪFiletimestamp:ChangeNumberChangeNumberIISõĸı䡣վõIJͬIISChangeNumberҲͬ ͬķϵApacheIISʹȫͬݲETagҲͬûյһС304Ӧ෴ǻһ200Ӧȫݡվֻһ̨ϣͲ⡣վǼڶϣʹApacheIISĬϵETagãûҳͻһ㣬ᴫݣռøĴҲЧػվݡʹӵExpiresļͷûʲôʱˢ¡ߡءťᷢӦGET
ûʹETagṩ֤ģʽôɴеETagȥáLast-Modifiedļͷ֤ǻݵʱġȥETagļͷӦ´ļĴСƪ֧ĸ彲ȥETagApacheУֻҪļмһдͿˣ
FileETag none
15ˢ
ûһҳʱζỨ200500ں̨֯HTMLļڼ䣬һֱеȴݷءPHPУʹflush()ѾĺõIJHTMLӦļȷʱͻļеݣűȣ̨ͬʱʣHTMLҳ档Чں̨ջǰ̨Ͽʱԡ
Ӧõһطǽ<head />֮ΪHTMLͷɶͷCSSJavaScriptļͿں̨ʣHTMLͬʱǡ ӣ
... <!-- css, js -->
</head>
<?php flush(); ?>
<body>
... <!-- content -->
Ϊ֤ʹĺôYahoo!оûԡ
16ʹGETAJAX
Yahoo!MailŶӷ֣ʹXMLHttpRequestʱеPOSTһߡḶ́ȷļͷȻŷݡʹGETΪǡΪֻ跢һTCPкܶcookieIEURLΪ2KҪһ2KʱͲʹGETˡ
һȤIJͬPOSTGETʵʷݡHTTP淶GETζšȡݣ˵ȡʱʹGET壨ϽҲˣ෴Ͳڷ˱ʱʹPOST
17ʽڶ
оYahoo!ܱʱǷְʽŵĵ<head />ڲƺӿҳٶȡΪʽŵ<head />ڻʹҳвļʾ
עܵǰ˷ϣҳؼءͬʱҲϣѾյݾʾӵн϶ݵҳٽû˵رҪûؿӻķָ룬Ѿ˽ϺõоγʽĵǵоHTMLҳǽָ롣ؼļͷlogoȶڵȴҳصû˵Ϊӻķϸû顣
ʽĵײڰInternet Explorerڵĺֹܶݵֹ֡Ϊ˱ʽıҳԪػ档ûòһհҳ档
HTML淶ָʽҪŰҳ<head />ڣ<a />ͬ<link />ֻܳĵ<head />ڣԶʹdzûʽݶֵȥԡõķǰHTML淶ĵ<head />ڼʽ
18ʹCSSʽExpression
CSSʽǶ̬CSSԵǿΣգInternet Explorerӵ5汾ʼ֧CSSʽУʹCSSʽʵָһСʱлһαɫ
background-color: expression( (new Date()).getHours()%2 ? "#B8D4FF" : "#F08A00" );
ʾexpressionʹJavaScriptʽCSSԸJavaScriptʽļáexpressionвãڿеInternet ExplorerʱȽá
ʽļƵҪĶࡣҳʾʱҳƶʱҪ¼һΡCSSʽһԸٱʽļƵʡҳƶ궼ɴﵽ10000ϵļ
һCSSʽķʹһԵıʽڵһʱָʽԣCSSʽʽԱҳڶ̬ظı䣬ʹ¼CSSʽһа취ʹCSSʽһҪסҪǧβҿܻҳܲӰ졣
19ʹⲿJavaScriptCSS
ܹܶǹδⲿļġǣȡЩʩǰܻʵһ⣺JavaScriptCSSӦ÷ⲿļػǰǷҳ汾֮أ
ʵӦʹⲿļҳٶȣΪJavaScriptCSSļв档HTMLĵеJavaScriptCSSÿHTMLĵءȻHTTPĴȴHTMLĵĴСһ˵ⲿļеJavaScriptCSS棬ûHTTPͬʱԼHTMLĵĴС
ؼǣⲿJavaScriptCSSļƵʺHTMLĵĴйءȻһѶȣȻһЩָһһỰûվеĶҳ棬ЩҳлظʹͬĽűʽⲿļͻ洦
վûйܽЩָꡣЩվ˵õļǰJavaScriptCSSΪⲿļáȽʺʹôվҳYahoo!ҳMy Yahoo!ҳһλỰӵн٣ֻһΣԷJavaScriptCSSնû˵ӿӦʱ 䡣
ӵнϴҳ˵һּƽôHTTPͨʹⲿļлĺôһҳJavaScriptCSSҳɺ̬ⲿļҳʹõЩļʱѾ浽ˡ
20JavaScriptCSS
ָȥ벻ҪַļСӶʡʱ䡣ʱеע͡ҪĿհַոСtabȶҪȥJavaScriptУҪصļС˴ӶʡӦʱ䡣JavaScriptĿǰõ㷺JSMinYUI CompressorYUI CompressorھCSS
һֿԴŻķַҪȾһЩڻĹ̸ײ⡣ڶǰ10վĵз֣ҲСԭ21%Դﵽ25%ܻԸõ룬ǶJavaScript˵ķոС
ⲿĽűʽļ⣬<script><style>ҲԲӦýʹGzipѹűʽЩļȻԽʡ5%ϵĿռ䡣JavaScriptCSSĹܺӣ뽫洦
21<link>@import
ǰʵᵽCSSӦ÷ڶس֡
IEУҳײ@importʹ<link>һģòҪʹ
22ʹ˾
IEAlphaImageLoader7.0°汾ʾPNGͼƬİЧ˾ͼƬʱֹݵijֲҶÿһԪأͼƬһΣڴ濪֧Ƕġ
ȫʹAlphaImageLoader÷ʹPNG8ʽ棬ָʽIEкܺõعȷʵҪʹAlphaImageLoaderʹ»_filterʹ֮IE7ϰ汾ûЧ
23ѽűҳײ
űֹҳƽءHTTP/1.1 淶飬ÿIJݲͼƬڶϣÿͬʱ2ϵļǵؽűʱͲͬʱļˣͬ
ijЩ°ѽűƵҳײ̫ܲס˵űʹdocument.writeҳݣͲܱƶˡܻ⡣ܶ£ⷽ⡣
һõʹӳٽűDEFERԱűûаdocument.writeʾҵǣFirefox֧DEFERԡInternet ExplorerУűܻᱻӳٵЧҲűԱӳ٣ôͿƵҳĵײҳصĿһ㡣
24ظű
ͬһҳظJavaScriptļӰҳܡܻΪǰ10վĵʾҴظýűҪصһűظõŶӹģͽűĴظűҪHTTPõJavaScript㣬⽵վܡ
Internet ExplorerлҪHTTPFirefoxȴᡣInternet ExplorerУһűζֲɻ棬ͻҳعвHTTPʱűԻ棬ûҳʱҲHTTP
ӶHTTP⣬űҲ˷ʱ䡣Internet ExplorerFirefoxвܽűǷɻ棬ǶظJavaScript⡣
һżͬһűķģʹýűģýűHTMLҳʹ<script />ǩýűǣ
<script type="text/javascript" src="menu_1.0.17.js"></script>
PHPпͨΪinsertScriptķ
<?php insertScript("menu.js") ?>
Ϊ˷ֹظýűлӦʹűĿ¼ΪűļӰ汾Expireļͷȡ
25DOM
ʹJavaScriptDOMԪرȽΪ˻øӦҳ棬Ӧ
ѾʹйԪ
¸ڵ֮ٽӵĵ
ʹJavaScriptҳ沼
йش˷ĸϢ鿴Julien LecomteYUIרе¡AjaxӦó
26¼
ʱǻоҳ淴ӦٶۣΪDOMԪи˹¼Щ¼䲡ƵشΪʲô˵ʹevent delegation¼һֺ÷ˡһdiv10ťֻҪdivϸһ¼ͿˣȥΪÿһťһ¼ðʱԲ¼жϳĸ¼ġ
ͬҲΪ˲DOMȴonload¼ķҪľǵȴṹҪʵԪس֡Ҳõȴͼϡ
ܻϣDOMContentLoaded¼onload֧֮ǰʹYUI ¼ӦóеonAvailable
27СCookie
HTTP coockieȨ֤Իݵȶ;coockieڵйϢͨHTTPļͷweb֮нġ˱coockieܵСԼûӦʱʮҪ
йظϢԲ鿴Tenni TheurerPatty Chi¡When the Cookie CrumblesоҪ
ȥҪcoockie
ʹcoockieСԼٶûӦӰ
עӦcoockieԱʹӰ
úĹʱ䡣ExpireʱͲҪȥcoockieûӦʱ䡣
28ҳʹcoockie
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