hypertext transfer protocol

• an application layer protocol in the internet protocol suite
• foundation of data communication for the web
• encrypted extension: https, s for secure

Client/server model §

Request §

A message sent from client -> server.

Syntax §

• A request line method URL protocol_version
  • e.g. GET /images/logo.png HTTP/1.1

• Header fields “ §

Methods include

• GET
• HEAD
• POST

Response §

A message sent from server -> client in response

Syntax §

• A status line protocol_version status_code reason_phrase
  • e.g. HTTP/1.1 200 OK
• 0 or more response header fields

status codes §

1XX (informational)

The request was received, continuing process.

2XX (successful)

The request was successfully received, understood, and accepted.

3XX (redirection)

Further action needs to be taken in order to complete the request.

4XX (client error)

The request contains bad syntax or cannot be fulfilled.

5XX (server error)

The server failed to fulfill an apparently valid request.