IAP using HTTP

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IAP using HTTP

3.1

HTTP overview

HyperText Transfer Protocol is the underlying protocol used by the World Wide Web. HTTP

defines how messages are formatted and transmitted, and what actions Web servers and

browsers should take in response to various commands.

The HTTP protocol is a request/response protocol. Most HTTP communication is initiated

by a user agent and consists of a request to be applied to a resource on the origin server. In

the simplest case, this may be accomplished via a single connection between the user

agent and the origin server.

3.2

Request methods

HTTP Requests are primarily requests sent by the client browser to the web server

software. These requests are coded into the packet as plain text. They inform the Web

server what the client is looking for and indicate how the server should go about delivering

the content or service requested.

A request message from a client to a server includes, within the first line of that message,

the method to be applied to the resource, the identifier of the resource, and the protocol

version in use.

HTTP defines eight methods indicating the desired action to be performed on the identified

resource.

3.3

Uploading files with HTTP

The HTTP protocol offers the possibility to upload files using HTML forms that allow the

producer of the form to submit files of data requested from the user reading the form.

Table 3.

HTTP request methods

Method

Description

GET

Requests a representation of the specified resource.

HEAD

Asks for the response identical to the one that would correspond to a GET

request, but without the response body.

POST

Submits data to be processed (e.g. from an HTML form) to the identified

resource.

PUT

Uploads a representation of the specified resource.

DELETE

Deletes the specified resource.

TRACE

Echoes back the received request, so that a client can see what intermediate

servers are adding or changing in the request.

OPTIONS

Returns the HTTP methods that the server supports. This can be used

to check the functionality of a web server.

CONNECT

For use with a proxy that can change to being an SSL tunnel.