[HTTP] Basic

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Intro

Before an HTTP client can send a message to a server, it needs to establish a TCP/IP connection between the clien and the server using Internet Protocal (IP) addresses and port numbers.

TCP requires:

  • IP Address of host server computer
  • TCP Port number

All of these can get from URL. If port number is not provided, it’s default port 80.

URL

Nine-part general URL format:

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<scheme>://<user>:<password>@<host>:<port>/<path>;<params>?<query>#<frag>

Each path segment can have its own params component

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http://www.joes-hardware.com/hammers;sale=false/index.html;graphics=true

RTSP URLs are identifiers for audio and video media resources that cen be retrieved through the Real Time Streaming Protocal.

Message

No message is going upstream.

Request message format:

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

<entity-body>

Response message:

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<version> <status> <reson-phrase>
<headers>

<entity-body>

A set of HTTP headers should always end in a blank line (bare CRLF). However, clients and servers should accept messages without the final CRLF.

Overall Range Defined Range Category
100-199 100-101 Informational
200-299 200-206 Successful
300-399 300-305 Redirection
400-499 400-415 Client Error
500-599 500-505 Server Error