How do I enable gzip compression when using MVC3 on IIS7?

Question

Does anybody know how to enable gzip compression in MVC 3? I'm using IIS7.

Google Chrome Audit's result:

1. Enable gzip compression (4)
2. Compressing the following resources with gzip could reduce their transfer size by about two thirds (~92.23KB):
3. /mydomain/ could save ~1.53KB
4. jquery-1.4.4.min.js could save ~51.35KB
5. Cufon.js could save ~11.89KB
6. Futura.js could save ~27.46KB

Answer 1

You can configure compression through your web.config file as follows:

<system.webServer>
    <urlCompression doStaticCompression="true" doDynamicCompression="true" />
</system.webServer>

You can find documentation of this configuration element at iis.net/ConfigReference. This is the equivalent of:

1. Opening Internet Information Services (IIS Manager)
2. Navigating through the tree-view on the left until you reach the virtual directory you wish to modify
3. Selecting the appropriate virtual directory so that the title of the right-hand pane becomes the name of said virtual directory.
4. Choosing "Compression" under "IIS" in the right-hand pane
5. Ticking both options and choosing "Apply" under "Actions" on the far right.

Note: (As pointed out in the comments) You need to ensure that Http Dynamic Compression is installed otherwise setting doDynamicCompression="true" will not have any effect. The quickest way to do this is:

1. Start > Type optionalfeatures (this is the quickest way to get to the "Turn Windows Features on or off" window)
2. Navigate to Internet Information Services > World Wide Web Services > Performance Features in the "Windows Features" treeview
3. Ensure "Dynamic Content Compression" is ticked
4. Click "Ok" and wait whilst Windows installs the component

Answer 2

You could do this in code if you rather do that. I would make a basecontroller which every control inherits from and decorate it with this attribute below.

public class CompressAttribute : ActionFilterAttribute
{
    public override void OnActionExecuting(ActionExecutingContext filterContext)
    {

        var encodingsAccepted = filterContext.HttpContext.Request.Headers["Accept-Encoding"];
        if (string.IsNullOrEmpty(encodingsAccepted)) return;

        encodingsAccepted = encodingsAccepted.ToLowerInvariant();
        var response = filterContext.HttpContext.Response;

        if (encodingsAccepted.Contains("deflate"))
        {
            response.AppendHeader("Content-encoding", "deflate");
            response.Filter = new DeflateStream(response.Filter, CompressionMode.Compress);
        }
        else if (encodingsAccepted.Contains("gzip"))
        {
            response.AppendHeader("Content-encoding", "gzip");
            response.Filter = new GZipStream(response.Filter, CompressionMode.Compress);
        }
    }
}

Answer 3

Compression is enabled/disabled at the server's level. See IIS compression module in iis management console.

Here are the instructions for IIS from microsoft site.