A simple > PHP5.3 plugin system supporting plugin descriptor files and extension points. It is inspired by the eclipse and jira plugin architectures. In combination with a dependency manager (Composer), a module system (for example Symfony bundles) and a dependency injection framework (for example the Symfony service container) this provides a very powerfull way of building a pluggable architecture in a PHP application. It can be easily extended to filter loaded plugins based on your own criteria which allows for different levels op application functionalities (maybe based on subscription level).

• Registry :: Container of shared objects (for example plugins and extension points)
• Locators :: Objects that locate installed plugins
• Activators :: Objects athat provide different ways to activate plugins
• Loader :: Loads and parses plugin declaration and register it on the plugin registry

composer require gheevel/phpplugin

Create a directory for plugins with a new plugin directory containing a plugin.xml file and a plugin class. (Directories may be nested)

<?xml version="1.0" encoding="UTF-8" ?>
<plugin>
    <name>company/plugin</name>
    <pluginClass>Company\Plugin\Plugin</pluginClass> <!-- Just extend AbstractPlugin or implement PluginInterface //-->
    <extension type="some.extension.type.identifier" className="Some\ClassOne" customPropertyOne="one" />
    <extension type="some.extension.type.identifier" className="Some\ClassTwo" customPropertyTwo="two" />
</plugin>

<?php
namespace Company\Plugin;

use PHPPlugin\PluginSystem\AbstractPlugin;

class Plugin extends AbstractPlugin
{
    
}

<?php
use PHPPlugin\PluginSystem\ComponentAccessor;

// Or preferably inject with a dependency injection container
$pluginRegistry = ComponentAccessor::getInstance()->getPluginRegistry(); 

$pluginRegistry
    ->getPluginLocator('PHPPlugin\PluginSystem\Locator\RecursiveDirectoryPluginLocator')
    ->addPath('vendor');

// Now all extensions are available through proxy instances.
$pluginRegistry->activate();

// Or preferably inject with a dependency injection container
$extensionRegistry = ComponentAccessor::getInstance()->getExtensionRegistry();

$extensionRegistry->getExtensionsByType('some.extension.type.identifier');
$extensionRegistry->getExtensionByClassName('Some\Class');