Problem with MVC 1.0 compression actionfilter and IIS 7 RSS

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  rfrancis48

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  Problem with MVC 1.0 compression actionfilter and IIS 7

  Apr 23, 2009 03:42 PM|LINK

   

  Hello. There seems to be a bug in either MVC 1.0 or IIS 7 that causes server errors to render improperly when the response is returned to the browser. Basically, when a server error occurs, I should get the standard error page from asp.net, telling me the file and line of code where the error occurred. But instead I get a bunch of weird, binary-like data.
  

  As a test scenario, I have created a default asp.net mvc application, and have applied my compression actionfilter attribute to the Home controller.
  Then, I added some code under the About action to manually throw a generic exception.

  When running under the local VS development server, the server error renders correctly in the browser. When I publish the application to our local staging IIS7 server, the page returns the aforementioned junk data.
  The response code returns 500 as it should, though.
  

  Here is the CompressionFilter code:
  

  public class CompressFilter : ActionFilterAttribute
      {
          public override void OnActionExecuting(ActionExecutingContext filterContext)
          {
              HttpRequestBase request = filterContext.HttpContext.Request;
  
              string acceptEncoding = request.Headers["Accept-Encoding"];
  
              if (string.IsNullOrEmpty(acceptEncoding)) return;
  
              acceptEncoding = acceptEncoding.ToUpperInvariant();
  
              HttpResponseBase response = filterContext.HttpContext.Response;
  
              if (acceptEncoding.Contains("GZIP"))
              {
                  response.Filter = new GZipStream(response.Filter, CompressionMode.Compress);
                  response.AppendHeader("Content-encoding", "gzip");
              }
              else if (acceptEncoding.Contains("DEFLATE"))
              {
                  response.Filter = new DeflateStream(response.Filter, CompressionMode.Compress);
                  response.AppendHeader("Content-encoding", "deflate");
              }
          }
      }

  It almost seems like the output in the response is being compressed, but the Content-encoding header is cleared when an exception occurs.
  Debugging locally, I can see the same thing happening. When the page finishes loading, the Content-encoding header is not there:

  Server	ASP.NET Development Server/9.0.0.0
  Date	Thu, 23 Apr 2009 15:25:25 GMT
  X-AspNet-Version	2.0.50727
  Cache-Control	private
  Content-Type	text/html; charset=utf-8
  Content-Length	9793
  Connection	Close

   

  In disabling the compression filter, I found the content-length to be the same under the dev server. So its like the compression filter and header are ignored/cleared within the asp.net dev server. But in IIS7, compression is applied, but with no header.
  

  I know I can use Dynamic compression within IIS7 and disable the filter in code altogether, but I would still like to know what is going here.
  Also, as a workaround to solve the problem, I have found adding code within the Application_Error event handler to dispose of the response filter stream fixes the issue (response.filter.dispose()).

  Thanks
  

  asp.net mvc IIS7 gzip compression filter server error 500 binary characters