HTTP,協議,學習總結

1. 消息格式: start line + headers + body
   Request Message:

<method> <request-URL> <version>
<headers>
<entity-body>

Repsonse Message:
<version> <status> <reason-phrase>
<headers>
<entity-body>
2.一共7種Method

3. 一共5大類Status Code
   

4.基於TCP的HTTP問題
若是採用TCP短鏈接會帶來較大的延遲，緣由：

• TCP 三次握手(handshake)
• TCP 延時確認(delay ack)
• TCP 慢啓動（slow start）
• 服務器端頻繁關閉TCP，致使TIME_WAIT Accumulation and Port Exhaustion

解決辦法:

• Parallel connections
  Concurrent HTTP requests across multiple TCP connections
  並行多TCP鏈接，
• Persistent connections
  Reusing TCP connections to eliminate connect/close delays
  共有一個TCP長鏈接，HTTP/1.1 默認爲長鏈接
  消除TCP connection延時
  delays
• Pipelined connections
  Concurrent HTTP requests across a shared TCP connection
  消除數據傳輸延時（transfer latencies）

• Multiplexed connections
  Interleaving chunks of requests and responses (experimental)

  5. 緩存控制
     
     

不緩存！
Cache-Control: no-store
Cache-Control: no-cache do-notserve-from-cache-without-revalidation.
Pragma: no-cache
Cache-Control: must-revalidate