一文領略 HTTP 的前世今生

{"type":"doc","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"blockquote","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"每個時代，都不會虧待會學習的人。"}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"大家好，我是 yes。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"HTTP 協議在當今的互聯網可謂是隨處可見，一直默默的在背後支持着網絡世界的運行，對於我們程序員來說 HTTP 更是熟悉不過。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"平日裏我們都說架構是演進的，需求推動着技術的迭代、更新和進步，對於 HTTP 協議來說也是如此。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"不知你是否有想過 HTTP 協議是如何誕生的，一開始是怎樣的，又是怎麼一步一步發展到今天的 HTTP/3 ?"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"strong"}],"text":"其中經歷了哪些不爲人知的祕密？"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"今天我就想和大家一起來看一看 HTTP 的演進之路，來看看它是如何從一個小寶寶成長爲現在統治互聯網的存在。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"不過在此之前，我們先簡單的看看互聯網的始祖-阿帕網的一段小歷史，還是很有趣的。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"互聯網的始祖-阿帕網"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"在 1950 年代，通信研究者們認識到不同計算機用戶和網絡之間的需要通信，這促使了分佈式網絡、排隊論和封包交互的研究。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"在1958 年2月7日，美國國防部長尼爾 · 麥克爾羅伊發佈了國防部 5105.15 號指令，建立了高級研究計劃局(ARPA) 。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/3a/3a3d6746667ce407c860ea8eb72e1a6d.png","alt":null,"title":null,"style":null,"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"ARPA 的核心機構之一 IPTO（信息處理處）贊助的一項研究導致了阿帕網的開發。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"我們來看看這段歷史。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"在 1962 年，ARPA 的主任聘請約瑟夫·利克萊德擔任 IPTO 的第一任主任，他是最早預見到現代交互計算及其在各種應用的人之一。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"IPTO 資助了先進的計算機和網絡技術的研究，並委託十三個研究小組對人機交互和分佈式系統相關技術進行研究。"},{"type":"text","marks":[{"type":"strong"}],"text":"每個小組獲得的預算是正常研究補助金的三十至四十倍。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"這就是財大氣粗啊，研究人員肯定是幹勁十足！"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"在 1963 年利克萊德資助了一個名爲 MAC 的研究項目，"},{"type":"text","marks":[{"type":"strong"}],"text":"該項目旨在探索在分時計算機上建立社區的可能性"},{"type":"text","text":"。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"這個項目對 IPTO 和更廣泛的研究界產生了持久的影響，成爲廣泛聯網的原型。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"並且利克萊德的全球網絡願景極大地影響了他在 IPTO 的繼任者們。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"1964 年利克萊德跳槽到了 IBM，第二任主任薩瑟蘭上線，他創建了革命性的 Sketchpad 程序，用於存儲計算機顯示器的內存，在 1965 年他與麻省理工學院的勞倫斯 · 羅伯茨簽訂了 IPTO 合同，以進一步發展計算機網絡技術。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"隨後，羅伯茨和托馬斯 · 梅里爾在麻省理工學院的 TX-2 計算機和加利福尼亞的 Q-32 計算機之間，"},{"type":"text","marks":[{"type":"strong"}],"text":"通過撥號電話連接實現了第一個數據包交換"},{"type":"text","text":"。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"1966 年第三任主任鮑勃 · 泰勒上任，他深受利克萊德的影響，巧的是泰勒和利克萊德一樣也是個心理聲學家。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/f8/f8101b1e3f9dbbce5de81c3f01882e2e.png","alt":null,"title":"","style":[{"key":"width","value":"50%"},{"key":"bordertype","value":"none"}],"href":"","fromPaste":false,"pastePass":false}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"在泰勒的 IPTO 辦公室裏有三個不同的終端連接到三個不同的研究站點，他意識到這種架構將嚴重限制他擴展訪問多個站點的能力。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"於是他想着把一個終端連接到一個可以訪問多個站點的網絡上，並且從他在五角大樓的職位來說，他有這個能力去實現這個願景。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"美國國防部高級研究計劃局局長查理 · 赫茨菲爾德向泰勒承諾，如果 IPTO 能夠組織起來，他將提供 100 萬美元用於建立一個分佈式通信網絡。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"泰勒一聽舒服了，然後他對羅伯茨的工作印象很深刻，邀請他加入並領導這項工作，然後羅伯茨卻不樂意。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"泰勒不高興了，於是要求赫茨菲爾德"},{"type":"text","marks":[{"type":"strong"}],"text":"讓林肯實驗室的主任向羅伯茨施壓，要求他重新考慮"},{"type":"text","text":"，這最終促使羅伯茨緩和了態度，於1966年12月加入 IPTO 擔任首席科學家。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/4d/4d2b305b8def9a50b1668811cf86f4d5.png","alt":null,"title":"","style":[{"key":"width","value":"50%"},{"key":"bordertype","value":"none"}],"href":"","fromPaste":false,"pastePass":false}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"在 1968 年6月3日，羅伯茨向泰勒描述了建立阿帕網的計劃，18 天后，也就是 6 月 21 日，泰勒批准了這個計劃，14 個月後"},{"type":"text","marks":[{"type":"strong"}],"text":"阿帕網建立"},{"type":"text","text":"。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"當阿帕網順利發展時，泰勒於 1969 年9月將 IPTO 的管理權移交給羅伯茨。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"隨後羅伯茨離開 ARPA 成爲 Telenet 的 CEO ，而利克萊德再次回到 IPTO 擔任董事，以完成該組織的生命週期。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"至此，這段歷史暫告一段落，可以看到阿帕網之父羅伯茨還是被施壓的才接受這項任務，"},{"type":"text","marks":[{"type":"strong"}],"text":"最終創建了阿帕網，互聯網的始祖"},{"type":"text","text":"。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"也多虧了利克萊德的遠見和砸錢促進了技術的發展，ARPA 不僅成爲網絡誕生地，同樣也是電腦圖形、平行過程、計算機模擬飛行等重要成果的誕生地。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"歷史就是這麼的巧合和有趣。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"互聯網的歷史"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"在 1973 年 ARPA 網擴展成互聯網，第一批接入的有英國和挪威計算機，逐漸地成爲網絡連接的骨幹。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"strong"}],"text":"1974 年 ARPA 的羅伯特·卡恩和斯坦福的文頓·瑟夫提出TCP/IP 協議。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"1986 年，美國國家科學基金會（National Science Foundation，NSF）建立了大學之間互聯的骨幹網絡 NSFNET ，這是互聯網歷史上重要的一步，NSFNET 成爲新的骨幹，1990 年 ARPANET 退役。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"在 1990 年 ，"},{"type":"text","marks":[{"type":"strong"}],"text":"蒂姆·伯納斯-李（下文我就稱李老）"},{"type":"text","text":" 創建了運行萬維網所需的所有工具：超文本傳輸協議（HTTP）、超文本標記語言（HTML）、第一個網頁瀏覽器、第一個網頁服務器和第一個網站。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/f9/f9685dfeb8d1dcafbba8af16e5fba516.png","alt":null,"title":"","style":[{"key":"width","value":"50%"},{"key":"bordertype","value":"none"}],"href":"","fromPaste":false,"pastePass":false}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"至此，互聯網開啓了快速發展之路，HTTP 也開始了它的偉大征途。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"還有很多有趣的歷史，比如第一次瀏覽器大戰等等，之後有機會再談，今天我們的主角是 HTTP。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"接下來我們就看看 HTTP 各大版本的演進，來看看它是如何成長到今天這個樣子的。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"HTTP / 0.9 時代"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"在 1989 年，李老發表了一篇論文，文中提出了三項現在看來很平常的三個概念。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"bulletedlist","content":[{"type":"listitem","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"URI，統一資源標識符，作爲互聯網上的唯一標識。"}]}]},{"type":"listitem","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"HTML，超文本標記語言，描述超文本。"}]}]},{"type":"listitem","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"HTTP ，超文本傳輸協議，傳輸超文本。"}]}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"隨後李老就付之於行動，把這些都搞出來了，稱之爲萬維網（World Wide Web）。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"那時候是互聯網初期，計算機的處理能力包括網速等等都很弱，所以 HTTP 也逃脫不了那個時代的約束，"},{"type":"text","marks":[{"type":"strong"}],"text":"因此設計的非常簡單，而且也是純文本格式"},{"type":"text","text":"。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"李老當時的想法是文檔存在服務器裏面，我們只需要從服務器獲取文檔，"},{"type":"text","marks":[{"type":"strong"}],"text":"因此只有 “GET”，也不需要啥請求頭，並且拿完了就結束了，因此請求響應之後連接就斷了"},{"type":"text","text":"。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"這就是爲什麼 HTTP 設計爲文本協議，並且一開始只有“GET”、響應之後連接就斷了的原因了。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"在我們現在看來這協議太簡陋了，但是在當時這是互聯網發展的一大步！"},{"type":"text","marks":[{"type":"strong"}],"text":"一個東西從無到有是最困難的"},{"type":"text","text":"。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"這時候的 HTTP 還沒有版本號的，之所以稱之爲 HTTP / 0.9 是後人加上去了，爲了區別之後的版本。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"HTTP 1.0 時代"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"人們的需求是無止盡的，隨着圖像和音頻的發展，瀏覽器也在不斷的進步予以支持。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"在 1995 年又開發出了 Apache，簡化了 HTTP 服務器的搭建，越來越多的人用上了互聯網，這也促進了 HTTP 協議的修改。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"需求促使添加各種特性來滿足用戶的需求，經過了一系列的草案 HTTP/1.0 於 1996 年正式發佈。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"Dave Raggett 在1995年領導了 HTTP 工作組，他希望通過擴展操作、擴展協商、更豐富的元信息以及與安全協議相關的安全協議來擴展協議，這種安全協議通過添加額外的方法和頭字段來提高效率。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/51/51447f57910cbb154b43aea015ee11a5.png","alt":null,"title":"","style":[{"key":"width","value":"50%"},{"key":"bordertype","value":"none"}],"href":"","fromPaste":false,"pastePass":false}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"所以在 HTTP/1.0 版本主要增加以下幾點："}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"bulletedlist","content":[{"type":"listitem","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"增加了 HEAD、POST 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Content-Type，支持傳輸不同類型的數據，豐富了協議的載體，充實了用戶的眼球。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"但是那時候 HTTP/1.0 還不是標準，沒有實際的約束力，各方勢力不喫這一套，大白話就是你算老幾。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"HTTP 1.1 時代"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"HTTP/1.1 版本在 1997 的 RFC 2068 中首次被記錄，從 1995 年至 1999 年間的第一次瀏覽器大戰，極大的推動了 Web 的發展。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"隨着發展 HTTP/1.0 演進成了 HTTP/1.1，並且在 1999 年廢棄了之前的 RFC 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頭就可以判斷你到底是要訪問哪個主機。"}]}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/da/da097da99d9a9a858a02bf69bcad8329.png","alt":null,"title":null,"style":null,"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"可以看到瀏覽器大戰推進了 Web 的發展，也暴露出 HTTP/1.0 的不足之處，畢竟網絡帶寬等等都在進步，總不能讓協議限制了硬件的發展。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"因此提出了 HTTP/1.1 ，主要是爲了解決性能的問題，包括支持持久連接、pipeline、緩存管理等等，也添加了一些特性。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"再後來到 2014 年對 HTTP/1.1 又做了一次修訂，因爲其太過龐大和複雜，因此進行了拆分，弄成了六份小文檔 RFC7230 - RFC7235"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"這時候 HTTP/1.1 已經成了標準，其實標準往往是在各大強力競爭對手相對穩定之後建立的，因爲標準意味着統一，統一就不用費勁心思去兼容各種玩意。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"strong"}],"text":"只有強大的勢力才能定標準，當你足夠強大的時候你也可以定標準，去挑戰老標準。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"HTTP 2 時代"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"隨着 HTTP/1.1 的發佈，互聯網也開始了爆發式的增長，這種增長暴露出 HTTP 的不足，主要還是性能問題，而 HTTP/1.1 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Google 看不下去了，你不搞是吧？我自己搞我的，我自己和我自己玩，我用戶羣體大，我有 Chrome，我服務多了去了。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"Google 推出了 SPDY 協議，憑藉着它全球的佔有率超過了 60% 的底氣，2012年7月，開發 SPDY 的小組公開表示，它正在努力實現標準化。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"HTTP 坐不住了，之後互聯網標準化組織以 SPDY 爲基礎開始制定新版本的 HTTP 協議，最終在 2015 年發佈了 HTTP/2。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":" HTTP/2 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壓縮頭部，減少數據傳輸量。"}]}]},{"type":"listitem","content":[{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"允許服務端主動推送數據。"}]}]}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"strong"}],"text":"從文本到二進制"},{"type":"text","text":"其實簡化了整齊的複雜性，解析數據的開銷更小，數據更加緊湊，減少了網絡的延遲，提升了整體的吞吐量。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/4e/4ec2fa0d3d96c0b0cd3efac46187f2bf.png","alt":null,"title":null,"style":null,"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"strong"}],"text":"支持一個 TCP 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1.html，我把 1.html 需要的 js 和 css 也一塊送過去，省的之後客戶端再請求我要 js ，我要這個 css。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"可以看到 HTTP/2 的整體演進都是往性能優化的角度發展，因爲此時的性能就是痛點，"},{"type":"text","marks":[{"type":"strong"}],"text":"任何東西的演進都是哪裏痛醫哪裏。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"當然有一些例外，比如一些意外，或者就是“閒的蛋疼”的那種捯飭。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"這次推進屬於用戶揭竿而起爲之，你再不給我升級我自己搞了，我有着資本，你自己掂量。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"最終結果是好的，Google 後來放棄了 SPDY ，擁抱標準，而 HTTP/1.1 這個歷史包袱太重了，所以 HTTP/2 到現在也只有大致一半的網站使用它。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/0b/0bf6bd24d76f334115f050a18d3bc189.png","alt":null,"title":null,"style":null,"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"HTTP 3 時代"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"這 HTTP/2 還沒捂熱， HTTP/3 怎麼就來了？"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"這次又是 Google，它自己突破自己，主要也是源自於痛點，這次的痛點來自於 HTTP 依賴的 TCP。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"strong"}],"text":"TCP 是面向可靠的、有序的傳輸協議"},{"type":"text","text":"，因此會有失敗重傳和按序機制，而 HTTP/2 是所有流共享一個 TCP 連接，所以會有 "},{"type":"text","marks":[{"type":"strong"}],"text":"TCP 層面的隊頭阻塞"},{"type":"text","text":"，當發生重傳時會影響多個請求響應。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"並且 "},{"type":"text","marks":[{"type":"strong"}],"text":"TCP 是基於四元組（源IP，源端口，目標IP，目標端口）來確定連接的"},{"type":"text","text":"，而在移動網絡的情況下 IP 地址會頻繁的換，這會導致反覆的建連。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"還有 TCP 與 TLS 的疊加握手，增加了延時。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"問題就出在 TCP 身上，所以 Google 就把目光瞄向了 UDP。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"UDP 我們知道是無連接的，不管什麼順序，也不管你什麼丟包，而 TCP 我在之前的文章說的很清楚了"},{"type":"link","attrs":{"href":"https://mp.weixin.qq.com/s/DTUswaTsoUOCv4JL-t-mJg","title":""},"content":[{"type":"text","text":"TCP疑難雜症解析"}]},{"type":"text","text":"不瞭解的同學可以去看看。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"簡單的說就是 TCP 太無私了，或者說太保守了，現在需要一種更激進的做法。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"那怎麼搞? TCP 改不動我就換！然後把 TCP 可靠、有序的功能提到應用層來實現，因此 Google 就研究出了 QUIC 協議。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/69/696595cb2f38b5072d0e4c17e5fb1ed8.png","alt":null,"title":null,"style":null,"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"QUIC 層來實現自己的丟包重傳和擁塞控制，還有出於安全的考慮我們都會用 HTTPS ，所以需要多次握手。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/dc/dcb785d6c78baadfb00eda8155e0bcf3.png","alt":null,"title":null,"style":null,"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"上面我也已經提到了關於四元組的情況，所以在移動互聯網時代這握手的消耗就更加放大了，於是 QUIC 引入了個叫 Connection ID 來標識一個鏈接，所以切換網絡之後可以複用這個連接，達到 0 RTT 就能開始傳輸。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/15/15f3c414afeb2a56b47a5dc819de2a21.png","alt":null,"title":null,"style":null,"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"注意上圖是在已經和服務端握過手之後的，由於網絡切換等原因纔有 0 RTT ，"},{"type":"text","marks":[{"type":"strong"}],"text":"也就是 Connection ID 在之前生成過了"},{"type":"text","text":"。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"如果是第一次建連還是需要多次握手的，我們來看一下"},{"type":"text","marks":[{"type":"strong"}],"text":"簡化"},{"type":"text","text":"的握手對比圖。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/61/61a707e1b1738f132e120c220c83fa75.png","alt":null,"title":null,"style":null,"href":null,"fromPaste":true,"pastePass":true}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"所以所謂的 0RTT 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"},{"type":"text","marks":[{"type":"strong"}],"text":"HTTP over QUIC 更名爲 HTTP/3 並獲得批准"},{"type":"text","text":"。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"可以看到需求又推動技術的進步，由於 TCP 自身機制的限制，我們的目光已經往 UDP 上靠了，那 TCP 會不會成爲歷史呢？"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"我們拭目以待。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"heading","attrs":{"align":null,"level":2},"content":[{"type":"text","text":"最後"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"今天我們大致過了一遍 HTTP 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來說，不同的四元組你如何保證請求一定會轉發到之前的服務器上？"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"所以今天我只是淺顯的談了談大致的演進，具體的實現還是得靠各位自己摸索，或者之後有機會我再寫一些。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"不過相對於這些實現細節我更感興趣的是歷史的演進，這能讓我從時代背景等一些約束來得知，爲什麼這東西一開始是這麼設計的，從而更深刻的理解這玩意。"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","text":"而且歷史還是很有趣的，不是麼？"}]},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"horizontalrule"},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"image","attrs":{"src":"https://static001.geekbang.org/infoq/68/68a4b017b9f144c4770dc1a8847bd7a2.png","alt":null,"title":"","style":[{"key":"width","value":"50%"},{"key":"bordertype","value":"none"}],"href":"","fromPaste":false,"pastePass":false}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null}},{"type":"paragraph","attrs":{"indent":0,"number":0,"align":null,"origin":null},"content":[{"type":"text","marks":[{"type":"strong"}],"text":"我是 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