Caching in HTTP

初探 HTTP 1.1 Cache 機制，透過簡單的實驗來說明瀏覽器對於 HTPP Cache 的實作策略。

Transcript

1. Caching in HTTP
   SJ
   2016/07/25
   Email: sj@toright.com
   Blog: http://blog.toright.com
   

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2. 回顧 HTTP 1.1 的設計理念
   Architectural Styles and the Design of Network-based Software Architectures (by Roy Thomas
   Fielding)
   CHAPTER 5. Representational State Transfer (REST)
   

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3. HTTP Features
   ● HTTP 1.1 設計 Cache 的目的在降低
   Request 與 Full Response
   ● 以下兩個主要的設計理念
   ○ Expiration
   ○ Validation
   ● 實作上透過 Header 讓 Server 與 Client 可以
   自由定義 Cache 的方式
   

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4. HTTP 1.0 與 HTTP 1.1 Caching Difference
   HTTP 1.0 Reponse Cache Header
   ○ Expires
   ○ Pragma
   HTTP 1.1 Reponse Cache Header
   ○ Cache-Control
   

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5. 介紹 HTTP 1.1 Cache-Control Header
   ● Response Cache Header
   ○ no-store
   完全不 Cache
   ○ no-cache
   允許 Cache 但是每次都會檢查 Cache 狀態
   ○ max-age
   設定要 Cache 幾秒
   ○ private
   Cache 只給目前使用者使用
   ○ public
   Cache 可共用 (HTTPS不可共用)
   ○ must-revalidate
   交由 Client 自行決定要不要使用 Cache
   ● 可以混搭
   

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6. 如何檢查 Cache 是否有效？
   ● 時間導向 (秒為單位)
   Last-Modified / If-Modified-Since
   ● 檔案內容導向 (Hash)
   ETag / If-None-Match
   

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7. Cache-Control: no-store
   

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8. Cache-Control: no-cache
   

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9. Cache-Control: max-age
   

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10. Cache-Control: private
    

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11. Cache-Control: public
    

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12. Cache-Control: must-revalidate
    

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13. Reference
    ● HTTP 1.1 RFC 2616 - 14.9 Cache-Control
    ● HTTP 1.1 RFC 2616 - 13 Caching in HTTP
    ● Architectural Styles and the Design of
    Network-based Software Architectures - 5
    Representational State Transfer (REST)
    

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14. Thanks!
    The End
    Email: sj@toright.com
    Blog: http://blog.toright.com
    

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