Understanding the MVC Application Execution Process

 

Requests to an ASP.NET MVC-based Web application first pass through the UrlRoutingModule object, which is an HTTP module. This module parses the request and performs route selection. The UrlRoutingModule object selects the first route object that matches the current request. (A route object is a class that implements RouteBase, and is typically an instance of the Route class.) If no routes match, the UrlRoutingModule object does nothing and lets the request fall back to the regular ASP.NET or IIS request processing.

From the selected Route object, the UrlRoutingModule object obtains an object that implements the IRouteHandler interface and that is associated with the Route object. Typically, in an MVC application, this will be an instance of the MvcRouteHandler class. The MvcRouteHandler instance creates an MvcHandler object that implements the IHttpHandler interface. The MvcHandler object then selects the controller that will ultimately handle the request. For more information, see ASP.NET Routing.

 

Stage	Details
Receive first request for the application	In the Global.asax file, Route objects are added to the RouteTable object.
Perform routing	The UrlRoutingModule module uses the first matching Route object in the RouteTable collection to create the RouteData object, which it then uses to create a RequestContext object.
Create MVC request handler	The MvcRouteHandler object creates an instance of the MvcHandler class and passes the RequestContext instance to the handler.
Create controller	The MvcHandler object uses the RequestContext instance to identify the IControllerFactory object (typically an instance of the DefaultControllerFactory class) to create the controller instance with.
Execute controller	The MvcHandler instance calls the controller's Execute method.
Invoke action	For controllers that inherit from the ControllerBase class, the ControllerActionInvoker object that is associated with the controller determines which action method of the controller class to call, and then calls that method.
Execute result	The action method receives user input, prepares the appropriate response data, and then executes the result by returning a result type. The built-in result types that can be executed include the following: ViewResult (which renders a view and is the most-often used result type), RedirectToRouteResult, RedirectResult, ContentResult, JsonResult, FileResult, and EmptyResult.