WebResource.axd and HTTP Headers

Question

Our site just moved from .NET 1.1 to .NET 3.5, and in the process updated our 3rd party server controls. One of these packages uses javascript provided via WebResource.axd. These are included as normal <script src="" /> tags.

Watching the traffic, however, I see that these javascript files are coming across with headers that prevent client-side caching. And we're talking a lot of javascript. The headers in question:

Cache-control: no-cache, no-store
pragma: no-cache
Expires: -1

Are these headers configurable in .NET somewhere? Can I intercept these requests short of building an HttpModule? Is this something I can blame the control vendor for? <brandish weapon="blameGun" />

Thanks,

Baron

Answer 1

You could try:

HttpContext.Current.Response.Cache.SetCacheability(HttpCacheability.Public);

The other types of HttpCacheability are documented here:

http://msdn.microsoft.com/en-us/library/system.web.httpcacheability.aspx

Edit:

You can throw this in your Global.asax file instead of a module:

void Application_AuthorizeRequest(object sender, EventArgs e)
{
    if (Request.Path.IndexOf("WebResource.axd") > -1)
    {
        Response.Cache.SetCacheability(HttpCacheability.Public);
    }
}

Answer 2

This may occur if your web site is deployed with <compilation debug="true"> set in its web.config. Caching is disabled in this case for easier debugging of JavaScript files served as embedded resources. The solution is to simply set the debug attribute of the compilation tag to false. More info can be found in this excellent blog post.

Answer 3

Thanks for your responses. It turned out we already had the HttpModule that I didn't want to write in place, and it was the source of the problem.