Hi John,
Thanks a lot for your post. My configuration is: .NET 2.0.50727, Visual
Studio 2005 and I am using C#. I don't know anything about the server
other than I can POST files to a URI. Also, the way I am using
HttpWebRequest is taken from the MSDN pages. The actual Abort() in my
application works ok, but the upload does not stop.
I am not quite sure what you mean by:
If I understand you correctly, you've already POSTed a file to the
server, and you've issued the GetResponse, yet when you abort it, ...
My understanding so far was that calling GetResponse starts the actual
POSTing of the file, because this is when I see the network becoming
quite busy, but I may be wrong here. From your sentence above I gather
that POSTing to the server occurs before calling GetResponse, maybe when
I write to the request stream? And GetResponse only waits for the
response from the server. Is that correct?
I think your understanding of my problem is correct, but it is not the
server that keeps sending data, it seems that my machine keeps sending
data to the server. When I start my app and I abort the upload a few
seconds later, a 1.6 MB file will still be uploaded.
Here is a short code snippet. This is an async version. The scenario is:
My Background worker thread calls Upload and then the GUI thread calls
Abort. BeginGetResponse will be aborted correctly, but the file keeps on
being uploaded.
public void Abort()
{
this.req.Abort();
}
public void Upload(Uri uri)
{
try
{
this.req = (WebRequest.Create(uri) as HttpWebRequest);
this.req.Method = "POST";
this.postData = new MemoryStream();
/* Create data to POST */
this.req.ContentLength = this.postData.Length;
this.req.BeginGetRequestStream(
new AsyncCallback(ReadCallback), this.req);
allDone.WaitOne();
allDone.Reset();
IAsyncResult rest = this.req.BeginGetResponse(new
AsyncCallback(RespCallback), this.req);
allDone.WaitOne();
}
catch (Exception exc)
{
Console.WriteLine("WebRequest aborted");
Console.WriteLine(exc.Message);
}
}
// First Callback
private void ReadCallback(IAsyncResult asynchronousResult)
{
HttpWebRequest request = (HttpWebRequest)asynchronousResult.AsyncState;
using (Stream s = request.EndGetRequestStream(asynchronousResult))
this.postData.WriteTo(s);
this.postData.Close();
allDone.Set();
}
// Second Callback
private void RespCallback(IAsyncResult asynchronousResult)
{
try
{
HttpWebRequest request =
(HttpWebRequest)asynchronousResult.AsyncState;
HttpWebResponse response =
(HttpWebResponse)request.EndGetResponse(asynchrono usResult);
StreamReader sr = new StreamReader(response.GetResponseStream());
string strResp = sr.ReadToEnd().Trim();
allDone.Set();
}
catch (WebException e)
{
Debug.WriteLine("\nRespCallback Exception raised!");
Debug.WriteLine("\nMessage:{0}", e.Message);
}
}
Thanks again for your help.
Best wishes,
Marc.
John Saunders [MVP] schrieb:
"Marc Bartsch" <m.*******@reading.ac.ukwrote in message
news:4i*****************@newsfe5-win.ntli.net...
>Hi,
I have a background worker in my C# app that makes a synchronous
HttpWebRequest.GetResponse() call. The idea is to POST a file to a
server on the internet. When I call HttpWebRequest.Abort() on the
request object on another thread, GetResponse() returns with an
exception as expected. However, when I monitor the network traffic, it
does not seem to stop, but to continue to be active and to upload the
file. The network is active even after I close down my application
completely and the file will be posted to the server even if that
takes another few minutes.
My expectation was that with calling Abort(), GetResponse() would
return with an exception and all network traffic that relates to this
upload would stop, but it seems that I am wrong here. Has anyone an
idea why this is the case?
If I understand you correctly, you've already POSTed a file to the
server, and you've issued the GetResponse, yet when you abort it, the
server keeps sending you data?
Why should it stop? Answer: it should not stop, as nobody has told it to
stop. No message traveled from the client to the server saying: stop.
In fact, I don't believe that there _is_ such a message that can be
sent. At best, the TCP connection could be closed, but the server may
not detect that until it does a read from the connection.
Please confirm my understanding of your issue, and provide more detail
of the configuration. In particular, what software is running on client
and server, what versions, etc.
