Zend_Controller_Front implementa un Front Controller pattern usado en aplicaciones Model-View-Controller (MVC). Su propósito es inicializar el medio ambiente de la solicitud, rutear la solicitud entrante, y luego hacer un dispatch de cualquier de las acciones descubiertas; le agrega las respuestas y las regresa cuando se completa el proceso. Zend_Controller_Front también implementa el Singleton pattern, significando que solo una única instancia de él puede estar disponible en cualquier momento dado. Esto le permite actuar también como un registro en el que los demás objetos puden extraer del proceso dispatch. Zend_Controller_Front registra un plugin broker consígo mismo, permitiendo que diversos eventos que dispara sean observados por plugins. En muchos casos, esto da el desarrollador la oportunidad de adaptar el proceso de dispatch al sitio sin la necesidad de ampliar el Front Controller para añadir funcionalidad. Como mínimo, el front controller necesita una o más paths a directorios que contengan action controllers a fin de hacer su trabajo. Una variedad de métodos también pueden ser invocados para seguir adaptando el medio ambiente del front controller y ese a sus helper classes. Por defecto, el front controller carga el ErrorHandler plugin, así como al ViewRenderer action helper plugin. Estos son para simplificar el manejo de errores y el view renderering en sus controladores, respectivamente. Para deshabilitar el ErrorHandler, ejecutar lo siguiente en cualquier momento antes de llamar a dispatch(): setParam('noErrorHandler', true); ]]> Para deshabilitar el ViewRenderer, haga lo siguiente antes de llamar a dispatch(): setParam('noViewRenderer', true); ]]> El front controller tiene varios accessors para establecer su medio ambiente. Sin embargo, hay tres métodos básicos clave para la funcionalidad del front controller: getInstance() se utiliza para recuperar una instancia del front controller. Como el front controller implementa un patrón Singleton, este también es el único medio posible para instanciar un objeto front controller. setControllerDirectory() se usa para decirle a the dispatcher dónde buscar para los archivos de clase action controller. Acepta bien un único path o un array asociativo de pares módulo/path. Como algunos ejemplos: setControllerDirectory('../application/controllers'); // Establecer varios directorios módulos a la vez: $front->setControllerDirectory(array( 'default' => '../application/controllers', 'blog' => '../modules/blog/controllers', 'news' => '../modules/news/controllers', )); // Agregar un directorio de módulos 'foo': $front->addControllerDirectory('../modules/foo/controllers', 'foo'); ]]> Si usa addControllerDirectory() sin un nombre de módulo, este establecerá el directorio default para el módulo -- sobreescribiéndolo si ya existe. Puede conseguir la configuración actual para el directorio del controlador utilizando getControllerDirectory(); este devolverá un array de pares módulo/directorio. Uno de los aspectos del front controller es que puede definir una estructura modular de directorio para crear componentes standalone; estos son llamados "módulos". Cada módulo debe estar en su propio directorio y ser un espejo de la estructura del directorio del módulo por defecto -- es decir, que debería tener como mínimo un subdirectorio de "controladores", y típicamente un subdirectorio de "views" y otros subdirectorios de aplicaciones. addModuleDirectory() permite pasar el nombre de un directorio que contiene uno o más directorios de módulos. A continuación lo analiza y los añade como directorios de controladores al front controller. Después, si quiere determinar el path a un determinado módulo o al módulo actual, puede llamar a getModuleDirectory(), opcionalmente pasar un nombre de módulo para conseguir el directorio de ese módulo específico. dispatch(Zend_Controller_Request_Abstract $request = null, Zend_Controller_Response_Abstract $response = null) hace el trabajo pesado del front controller. Puede opcionalmente tomar un request object y/o un response object, permitiendo al desarrollador pasar objetos peronalizados para cada uno. Si no se pasa ningun objeto solicitud o respuesta, dispatch() comprobará por objetos previamente registrados y utilizar esos o instanciar versiones por defecto a utilizar en su proceso (en ambos casos, el sabor de HTTP será utilizado por defecto). Similarly, dispatch() checks for registered router and dispatcher objects, instantiating the default versions of each if none is found. The dispatch process has three distinct events: Routing Dispatching Response Routing takes place exactly once, using the values in the request object when dispatch() is called. Dispatching takes place in a loop; a request may either indicate multiple actions to dispatch, or the controller or a plugin may reset the request object to force additional actions to dispatch. When all is done, the front controller returns a response. Zend_Controller_Front::run($path) is a static method taking simply a path to a directory containing controllers. It fetches a front controller instance (via getInstance(), registers the path provided via setControllerDirectory(), and finally dispatches. Basically, run() is a convenience method that can be used for site setups that do not require customization of the front controller environment. In addition to the methods listed above, there are a number of accessor methods that can be used to affect the front controller environment -- and thus the environment of the classes to which the front controller delegates. resetInstance() can be used to clear all current settings. Its primary purpose is for testing, but it can also be used for instances where you wish to chain together multiple front controllers. (set|get)DefaultControllerName() let you specify a different name to use for the default controller ('index' is used otherwise) and retrieve the current value. They proxy to the dispatcher. (set|get)DefaultAction() let you specify a different name to use for the default action ('index' is used otherwise) and retrieve the current value. They proxy to the dispatcher. (set|get)Request() let you specify the request class or object to use during the dispatch process and to retrieve the current object. When setting the request object, you may pass in a request class name, in which case the method will load the class file and instantiate it. (set|get)Router() let you specify the router class or object to use during the dispatch process and to retrieve the current object. When setting the router object, you may pass in a router class name, in which case the method will load the class file and instantiate it. When retrieving the router object, it first checks to see if one is present, and if not, instantiates the default router (rewrite router). (set|get)BaseUrl() let you specify the base URL to strip when routing requests and to retrieve the current value. The value is provided to the request object just prior to routing. (set|get)Dispatcher() let you specify the dispatcher class or object to use during the dispatch process and retrieve the current object. When setting the dispatcher object, you may pass in a dispatcher class name, in which case the method will load the class file and instantiate it. When retrieving the dispatcher object, it first checks to see if one is present, and if not, instantiates the default dispatcher. (set|get)Response() let you specify the response class or object to use during the dispatch process and to retrieve the current object. When setting the response object, you may pass in a response class name, in which case the method will load the class file and instantiate it. registerPlugin(Zend_Controller_Plugin_Abstract $plugin, $stackIndex = null) allows you to register plugin objects. By setting the optional $stackIndex, you can control the order in which plugins will execute. unregisterPlugin($plugin) let you unregister plugin objects. $plugin may be either a plugin object or a string denoting the class of plugin to unregister. throwExceptions($flag) is used to turn on/off the ability to throw exceptions during the dispatch process. By default, exceptions are caught and placed in the response object; turning on throwExceptions() will override this behaviour. For more information, read . returnResponse($flag) is used to tell the front controller whether to return the response (true) from dispatch(), or if the response should be automatically emitted (false). By default, the response is automatically emitted (by calling Zend_Controller_Response_Abstract::sendResponse()); turning on returnResponse() will override this behaviour. Reasons to return the response include a desire to check for exceptions prior to emitting the response, needing to log various aspects of the response (such as headers), etc. In the introduction, we indicated that the front controller also acts as a registry for the various controller components. It does so through a family of "param" methods. These methods allow you to register arbitrary data -- objects and variables -- with the front controller to be retrieved at any time in the dispatch chain. These values are passed on to the router, dispatcher, and action controllers. The methods include: setParam($name, $value) allows you to set a single parameter of $name with value $value. setParams(array $params) allows you to set multiple parameters at once using an associative array. getParam($name) allows you to retrieve a single parameter at a time, using $name as the identifier. getParams() allows you to retrieve the entire list of parameters at once. clearParams() allows you to clear a single parameter (by passing a string identifier), multiple named parameters (by passing an array of string identifiers), or the entire parameter stack (by passing nothing). There are several pre-defined parameters that may be set that have specific uses in the dispatch chain: useDefaultControllerAlways is used to hint to the dispatcher to use the default controller in the default module for any request that is not dispatchable (i.e., the module, controller, and/or action do not exist). By default, this is off. See for more detailed information on using this setting. disableOutputBuffering is used to hint to the dispatcher that it should not use output buffering to capture output generated by action controllers. By default, the dispatcher captures any output and appends it to the response object body content. noViewRenderer is used to disable the ViewRenderer. Set this parameter to true to disable it. noErrorHandler is used to disable the Error Handler plugin. Set this parameter to true to disable it. To extend the Front Controller, at the very minimum you will need to override the getInstance() method: Overriding the getInstance() method ensures that subsequent calls to Zend_Controller_Front::getInstance() will return an instance of your new subclass instead of a Zend_Controller_Front instance -- this is particularly useful for some of the alternate routers and view helpers. Typically, you will not need to subclass the front controller unless you need to add new functionality (for instance, a plugin autoloader, or a way to specify action helper paths). Some points where you may want to alter behaviour may include modifying how controller directories are stored, or what default router or dispatcher are used.