WebRequest, Firefox, AllowReadStreamBuffering and custom headers

06-30-2008 11:21 PM |

This is either a Silverlight bug or a specific Firefox constraint.

->The following works fine in IE.

On the server side I have a HTTP handler that just writes a string to the Response stream (within a loop). On the client side, I set AllowReadStreamBuffering to false. If I set a custom header, it seems to "disable" the AllowReadStreamBuffering since the BeginGetResponse's Callback parameter is just called after my httphandler is done (same as if I set to true).

HTTP Handler code:

    public void ProcessRequest(HttpContext context)
    {
        context.Response.Write("Start write test"+'\n');
        
        //4kb chunk for IE for test purpose... related to another possible bug in IE
        //string bigfile = File.ReadAllText("c:\\bigfile.txt");
        //context.Response.Write(bigfile);
        //context.Response.Flush();

        int nbLoop = 20;
        while (nbLoop > 0)
        {
            Thread.Sleep(2000);

            context.Response.Write("Write test : " + nbLoop + '\n');
            context.Response.Flush();
            nbLoop--;
        }

        context.ApplicationInstance.CompleteRequest();
    }

Silverlight code: (called on a button's Click event)

    private void btnGo_Click(object sender, RoutedEventArgs e)
    {
        string serverUri = HtmlPage.Document.DocumentUri.AbsoluteUri;
        serverUri = serverUri.Substring(0, serverUri.LastIndexOf("/"));
        Uri uri = new Uri(String.Format("{0}/test.test", serverUri));

        HttpWebRequest req = WebRequest.Create(uri) as HttpWebRequest;
        req.AllowReadStreamBuffering = false;

        //uncomment the following to reproduce the bug
        //req.Headers["custom-header"] = "custom";

        req.BeginGetResponse(arResponse =>
        {
            //with AllowReadStreamBuffering=false, it should step here immediately
            using (HttpWebResponse svrResp = req.EndGetResponse(arResponse) as HttpWebResponse)
            {
                using (StreamReader sr = new StreamReader(svrResp.GetResponseStream()))
                {
                    int bsize = 256;
                    Char[] buffer = new Char[bsize];
                    int nbByte = sr.Read(buffer, 0, bsize);
                    while (nbByte > 0)
                    {
                        string resultingData = new String(buffer, 0, nbByte);
                        Debug.WriteLine(resultingData);
                        nbByte = sr.Read(buffer, 0, bsize);
                    }
                }
            }
        },null);
    }

I don't know if someone could confirm this? (I can email the complete VS solution if someone is interested)

Thanks

Re: WebRequest, Firefox, AllowReadStreamBuffering and custom headers

09-17-2008 2:29 PM |

I tried your code. I got the following exception "Error HRESULT E_FAIL has been returned from a call to a COM component".

When I set the request method to POST with
request.Method = "POST", I didn't get any exceptions and in Firefox, my silverlight app was able to receive every byte sent.

When I set the request method to POST with
request.Method = "GET", I again got an exception, due to, I believe, setting a header. So I commented out:
request.Headers["custom-header"]="value";
After that, it again worked as expected.


Do you think you are getting an exception when you invoke BeginGetResponse? Please let me know what you think.

Re: WebRequest, Firefox, AllowReadStreamBuffering and custom headers

09-17-2008 2:56 PM |

Ok, I'll undust it and see if I get the same result...

When you set request.Method to POST, can you see the "custom" header (name and value) on the server side?

Re: WebRequest, Firefox, AllowReadStreamBuffering and custom headers

09-17-2008 5:03 PM |

Yes. I can read the custom header and the value; the name of the header is HTTP_[name of the header where it is capitalized and - replaced by _] - if your header name is xyz_-abc, then it becomes HTTP_XYZ__ABC.