Professional ASP.NET MVC 3

Under the Hood: How Routes Tie Your URL to an Action

This section provides a peek under the hood to get a detailed understanding of how these pieces tie together. This will give you a better picture of where the dividing line is between routing and MVC.

One common misconception is that routing is just a feature of ASP.NET MVC. During early previews of ASP.NET MVC 1.0, this was true, but it quickly became apparent that Routing was a useful feature in its own right beyond ASP.NET MVC. For example, the ASP.NET Dynamic Data team was also interested in using Routing. At that point, Routing became a more general-purpose feature that had neither internal knowledge of nor a dependency on MVC.

To better understand how routing fits into the ASP.NET request pipeline, let's look at the steps involved in routing a request.

The discussion here focuses on routing for IIS 7 (and above) Integrated Mode. There are some slight differences when using routing with IIS 7 Classic Mode or IIS 6. When using the Visual Studio built-in web server, the behavior is very similar to the IIS 7 Integrated Mode.

The High-Level Request Routing Pipeline

The routing pipeline consists of the following high-level steps:

1. The UrlRoutingModule attempts to match the current request with the routes registered in the RouteTable.

2. If a route matches, the Routing module grabs the IRouteHandler from that route.

3. The ...