Re: [PROPOSAL] PHP Component Model

Hi Sebastian, well I remembered another issue: Any component model will bind a programmer, respectively a package to a certain framework! I don't know if this is really an aim of PEAR or PHP? Component model may be nice for your own projects, but should it be part of PEAR? In this case I think it should be discussed what features are missing ;-) Regards, Matthias Sebastian Bergmann wrote:

Hi, I would like to propose a package called PHP_ComponentModel which is the reference implementation of the PHP Component Model. The PHP Component Model is to become a standard for the development of exchangable components that can be customized and plugged together using PHP Development Environments (PHP IDEs). Quoting Philippe Krutchen from Rational Software "A component is a nontrival, nearly independent, and replaceable part of a system that fulfills a clear function in the context of a well-defined architecture. A component conforms to and provides the physical realization of a set of interfaces." At the core of the PHP Component Model is the Component Container. The Components register themselves with the Component Container and communicate among each other by the means of Events. When a component fires an event the event is first received by the Component Container which in turn broadcasts the event to all registered components. A PHP Component is a PHP class that adheres to the coding standards below. Upon instantiation a PHP Component registers itself automatically with the Component Container, loads its configuration and is then ready to respond to events. The configuration of PHP Components should be done using PHP Development Environments (PHP IDEs) that have support for the PHP Component Model Metadata format. A component class must * extend the PHP_ComponentModel_Component class, * provide two protected member arrays, $neededServices and

     $providedServices, that contain the names of the services that the
     component needs and provides,

* provide two protected member arrays, $incomingEvents and

     $outgoingEvents, that contain the class names of the events that
     the component fires and handles,

* implement the handleEvent(PHP_ComponentModel_Event $e) method. A component class may * implement the two methods start() and stop of the

     PHP_ComponentModel_Startable interface,

* implement the checkPropertyChange($propertyName, $value) method to

     check if a property change conforms with the property's bounds and
     return FALSE if it does not.

A class that follows these coding standards can be used as a PHP Component because it * is able to fire and handle events, * provides the introspection support needed for the Metadata system * and can thus be customized using PHP Development Environments (PHP

     IDEs) that have support for the PHP Component Model.

The PHP_ComponentModel_Container interface describes the functionality Component Containers need to implement to be used in the PHP Component model context. The already available DefaultContainer implementation needs to initialize the components for each request. The yet to be implemented SRMContainer will run each component in a separate Banana "thread". Source:

    http://www.sebastian-bergmann.de/PCOM/Component.phps
    http://www.sebastian-bergmann.de/PCOM/Container.phps
    http://www.sebastian-bergmann.de/PCOM/DefaultContainer.phps
    http://www.sebastian-bergmann.de/PCOM/DependencyException.phps
    http://www.sebastian-bergmann.de/PCOM/Event.phps
    http://www.sebastian-bergmann.de/PCOM/IllegalStateException.phps
    http://www.sebastian-bergmann.de/PCOM/Startable.phps

The next development cycle will focus on the Metadata system needed to customize components using PHP Development Environments (IDEs). For this purpose methods will be implemented that:

    * Generate an XML representation of a PHP Component.

    * Generate a PHP source skeleton from an XML representation of a
      PHP Component.

    * Serialize a PHP Component's customization into an XML
      representation.

    * Unserialize a PHP Component's customization from the above
      mentioned XML representation.

Greetings, Sebastian