ROUTES AND ROUTING
It is difficult to talk about controllers without including routes. The routing table is stored in the Global.asax file. The routing system enables you to define URL mapping routes and then handle the mapping to the right controller and actions. It also helps construct outgoing URLs used to call back to the controller/actions. ASP.NET provides some default routing. The default routing format is {controller}/{action}/ {id}. That means an HTTP request to http://myurl/Product/Detail/1 will look for the Detail action on the ProductController that accepts an integer as a parameter. The routing engine doesn’t know anything about ASP.NET MVC; its only job is to analyze URLs and pass control to the route handler. The route handler is there to find an HTTP handler, or an object imple- menting the IHttpHandler interface, for a request. MvcHandler, the default handler that comes with ASP.NET MVC, extracts the controller information by comparing the request with the template values in the routing table. The handler extracts the string and sends it to a control- ler factory that returns the appropriate controller. The controller factory is easily extendable by creating a custom controller factory that implements IControllerFactory.