Question

I am able to understand how routers are collected using collectRoutes() function. Then how magento tries to match router for the requested URL using match() function in dispatch() method.
But how magneto router initialize the specific Action Controller and Action method ?
What is the utility of controller_front_send_response_before and controller_front_send_response_after events?

Answer 1

Oh, this is very easy (if I understand your question correctly).

URL always has a route/controller/action structure.

So once Magento resolved the route (you said that you got how it works) it just uses controller token as the first part of a classname of your controller. So for instance if your controller token is mymodule and your extension prefix is Mygroup_Myextension it will try to instantiate Mygroup_Myextension_MymoduleController. That means your file have to be located in app/code/[community-or-local]/Mygroup/Myextension/controllers/MymoduleController.php.

Then Magento will use an action token to call a method inside of your class. So in case of action token set as myaction Magento will try to call myactionAction() method.

In fact both controller and action tokens can be omitted. In this case Magento will try to instantiate Mygroup_Myextension_IndexController and call indexAction() method of your extension.