About Architecture

Joomla! 1.5 is a three tiered system:-

* The top, Extensions layer, consists of Extensions to the Joomla Framework and its applications:
o Modules
o Components
o Templates
* The middle, Application layer, consists of applications that extend the Framework JApplication class. Currently there are four applications included in the Joomla distribution:-
o JInstallation is responsible for installing Joomla on a web server and is deleted after the installation procedure has been completed.
o JAdministrator is responsible for the back-end Administrator.
o JSite is responsible for the front-end of the website.
o XML-RPC supports remote administration of the Joomla website.
* The bottom, Framework layer, consists of:-
o the Joomla Framework itself, whose classes are listed below.
o Libraries that are required by the Framework or are installed for use by third-party developers.
o Plugins extend the functionality available in the Framework.