Professional ASP.NET MVC 4

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.

Note

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 when a request is handled by ASP.NET:

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

2. If one of the routes in the RouteTable matches, the Routing module grabs the IRouteHandler from that route.

3. The Routing module calls the ...