---
###### tags: `Note` `js` `javascript` `web` `HTTP`
---

# HTTP
> Hpyer Text Transport Protocol

## The request and response cycle


## http error code

* 404 not found
* 403 forbidden
* 401 no authorize
* 500 internal server error
* 503 server unavailable

## http success code
* 200 OK
* 201 created
* 202 accepted, etc

## http required method

* get
* post
* delete
* update

## HTTP Message Format

A message include:

* start line
* header field + CRLF
* CRLF: carriage return followed by line feed("\r\n")
* Main Message

### start line

#### Required: ==required method<== + ==request-target== + ==http version==

POST /home HTTP1.1

#### Response: ==http version== + ==status code== + ==status parse==

HTTP1.1 200 OK

### header field: <ins>**self-descriptive messages**</ins>

Host: echo.paw.cloud
Content-Type: application/json; charset=utf-8
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:53.0) Gecko/20100101 Firefox/53.0
Connection: close
Content-Length: 136

### Main Message

Example:

POST /?id=1 HTTP/1.1
Host: echo.paw.cloud
Content-Type: application/json; charset=utf-8
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:53.0) Gecko/20100101 Firefox/53.0
Connection: close
Content-Length: 136

{
  "status": "ok",
  "extended": true,
  "results": [
    {"value": 0, "type": "int64"},
    {"value": 1.0e+3, "type": "decimal"}
  ]
}