General

Joomla! 1.5 is a three tiered system. The bottom tier is the framework level and consists of the libraries and plugins (formerly known as mambots). The second tier is the application level and consists of the JApplication class. Currently there are three applications that ship with Joomla: JInstallation, JAdministrator and JSite. The application acts as the main controller for the page. The third tier is the extension level. This level is where all component, module, and template logic is executed and rendered.

Joomla Tiered Architecture

The Joomla! Framework consists of several different packages.

Framework Packages

Application Package

JApplication and related libraries

Cache Package

Cache libraries

Common Package

The common package houses the base classes as well as compatability and legacy libraries

Connector Package

Connector libraries such as FTP and LDAP clients

Database Package

JDatabase and related libraries

Document Package

Libraries for building and rendering pages

Filesystem Package

Libraries for interacting with the filesystem

i18n Package

Internationalization libraries

Installer Package

Libraries for installing extensions

Mail Package

E-Mail related libraries

Model Package

Data Access Object libraries

Parameter Package

Parameter manipulation and rendering libraries

Registry Package

Configuration store libraries

Template Package

Templating libraries

Utilities Package

Miscellaneous libraries

Classes

JFactory

This class is a factory class to create and return various framework objects.

JVersion

Class to hold the Joomla! version information.