Request Response

Recall that clients send requests to servers, and the data is translated using protocols.

Client and server

The HTTP protocol specifies how a browser and other web clients request resources from web servers.

Request¶

A request for a resource consists of REQUEST RESOURCE_URI PROTOCOL_VERSION.

GET /content/somepage.html HTTP/1.0

The client can optionally send request headers.

GET /content/somepage.html HTTP/1.1
Host: www.example.com
Connection: Keep-Alive

* A blank line after the last header indicates the end of the request. * The RESOURCE_URI string must not contain spaces - that is, exactly two spaces are allowed in the request.

Response¶

A response to a client begins PROTOCOL_VERSION RESPONSE_CODE REASON

HTTP/1.1 200 OK

* Optional headers can (and just about always do) follow the response line.

```
HTTP/1.1 301 Moved permanently
Content-Length: 322

<html><head><title>301 Moved permanently</title></head>
<body><p>The document has moved <a href="http://example.com/
pages/somepage.html">here</a>.</p><hr> .....
```

An extra blank line separates the request or response and its headers from any content to follow.

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