What is Ajax?
AJAX stands for Asynchronous JavaScript And XML
Ajax isn't a new technology. It is using the JavaScript-based XMLHttpRequest object to retrieve information from a web server in a dynamic manner (asynchronous)
Since Ajax uses JavaScript, this must be enabled on the client machine for this technology to work.
Request methods
HTTP defines eight methods.
- HEAD
- Asks for the response identical to the one that would correspond to a GET request, but without the response body. This is useful for retrieving meta-information written in response headers, without having to transport the entire content.
- GET
- Requests a representation of the specified resource. By far the most common method used on the Web today. Should not be used for operations that cause side-effects (using it for actions in web applications is a common misuse). See 'safe methods' below.
- POST
- Submits data to be processed (e.g. from an HTML form) to the identified resource. The data is included in the body of the request. This may result in the creation of a new resource or the updates of existing resources or both.
- 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
- Converts the request connection to a transparent TCP/IP tunnel, usually to facilitate SSL-encrypted communication (HTTPS) through an unencrypted HTTP proxy.
Ajax is a concept used to describe what happens on the client-side of the web system using server-side scripts.