How does AssemblyResourceLoader/ASP.Net handle If-Modified-Since header?

Question

I have an IHttpHandler similar to AssemblyResourceLoader. What it does is generate an image and then send it back to the browser.

In AssemblyResourceLoader there is a code block like this:

    HttpCachePolicy cache = context.Response.Cache;
    cache.SetCacheability(HttpCacheability.Public);
    cache.VaryByParams["d"] = true;
    cache.SetOmitVaryStar(true);
    cache.SetExpires(DateTime.Now + TimeSpan.FromDays(365.0));
    cache.SetValidUntilExpires(true);
    Pair assemblyInfo = GetAssemblyInfo(assembly);
    cache.SetLastModified(new DateTime((long) assemblyInfo.Second));

I have set up mine to emit the exact same headers as AssemblyResourceLoader. I set the Last-Modified header and the browser sends the If-Modified-Since header to my handler just as it does with AssemblyResourceLoader. The problem is this: My handler never returns the 304 like AssemblyResourceLoader does. I can't find anywhere in the AssemblyResourceLoader code where it deals with the If-Modified-Since header so I don't know how to deal with it myself. Does anybody know where ASP.Net does that and how I can get the same behavior out of my handler?

Thanks.

Answer 1

Looks like you need to do it yourself, but it's not hard: http://www.motobit.com/tips/detpg_net-last-modified/