Professional Joomla!

Chapter 9. Hooking into the Joomla! Foundation: Plug-Ins

You have already created modules and components, so now it's time to tackle the final Joomla programming extension: the plug-in. While a module is primarily for presentation and a component is chiefly for user interaction, Plug-ins sit at the lowest level of the system and can modify core Joomla functionality. In this chapter, you will create a simple Hello World plug-in, and then proceed to a far more complex plug-in that intercepts article content after Joomla has rendered it and make modifications to the page before it is sent to the visitor's browser.

After you've created and tested this pair of Plug-Ins, together with your previous comprehension of module and component programming, you will definitely be considered an advanced Joomla extension developer. The overview of the Joomla programming framework will complete your education. The framework is the actual skeleton of the Joomla CMS; it is made up of all classes that, once you understand them, you can leverage in direct use.

Joomla Plug-In Overview

Unlike modules that are all stored in the \modules folder or components that all exist in the \components folder, Plug-ins are categorized and grouped within folders that define their categories. For example, Plug-ins that provide search functionality are stored in the \plugins\search folder, while content Plug-ins exist in the \plugins\content folder.

In the Plugin Manager, the category of plug-in is generally displayed in ...