HTTP,协议,学习总结

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种Method

3. 一共5大类Status Code
   

4.基于TCP的HTTP问题
若是采用TCP短链接会带来较大的延迟，缘由：

• TCP 三次握手(handshake)
• TCP 延时确认(delay ack)
• TCP 慢启动（slow start）
• 服务器端频繁关闭TCP，致使TIME_WAIT Accumulation and Port Exhaustion

解决办法:

• Parallel connections
  Concurrent HTTP requests across multiple TCP connections
  并行多TCP链接，
• Persistent connections
  Reusing TCP connections to eliminate connect/close delays
  共有一个TCP长链接，HTTP/1.1 默认为长链接
  消除TCP connection延时
  delays
• Pipelined connections
  Concurrent HTTP requests across a shared TCP connection
  消除数据传输延时（transfer latencies）

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

  5. 缓存控制
     
     

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