AJAX Based Web Applications

Only very recently has it been widely noticed that web client technology has matured to a point that supports applications whose visual and interaction qualities are comparable to graphical user interfaces (GUIs) as they were known before the web.

Web applications can now offload a considerable part of the interaction and application logic to the client side, and thus reconcile the advantages in deployability, distributedness, and concurrency that the web provides with desirable properties of GUIs such as rich state, immediate feedback, and direct manipulation, which are sadly missing from pure HTML based web applications.

The technologies that enable this architecture are JavaScript, asynchronously handled HTTP requests, and XML, which in this combination are nowadays referred to as AJAX, and of which, although probably most well known, XML is the least essential.

Besides increasing the interactive quality, AJAX introduces a rather radical segregation of functionality and interaction into the architecture of web applications in that it requires a non trivial part of the application to be implemented in yet another programming language, JavaScript, and in that objects which are communicated between the parts of the application are marshalled through HTTP sessions. These requirements might seem to be burdensome at first but in fact they can considerably reduce the complexity into which purely server based web applications have evolved.