How to Set Asynchronous Operation timeout in. Net

From http://blog.csdn.net/newstarmoon/archive/2006/07/19/942231.aspx

The following example uses the BeginGetResponse method to send an asynchronous request to Internet resources. Note that in asynchronous requests, the client application is responsible for implementing its own timeout mechanism. The following example shows how to achieve this.

Using System;
Using System. Net;
Using System. IO;
Using System. Text;
Using System. Threading;

Public class RequestState
{
// This class stores the State of the request.
Const int BUFFER_SIZE = 1024;
Public StringBuilder requestData;
Public byte [] BufferRead;
Public HttpWebRequest request;
Public HttpWebResponse response;
Public Stream streamResponse;
Public RequestState ()
{
BufferRead = new byte [BUFFER_SIZE];
RequestData = new StringBuilder ("");
Request = null;
StreamResponse = null;
}
}

Class HttpWebRequest_BeginGetResponse
{
Public static ManualResetEvent allDone = new ManualResetEvent (false );
Const int BUFFER_SIZE = 1024;
Const int DefaultTimeout = 2x60*1000; // 2 minutes timeout
 
// Abort the request if the timer fires.
Private static void TimeoutCallback (object state, bool timedOut ){
If (timedOut ){
HttpWebRequest request = state as HttpWebRequest;
If (request! = Null ){
Request. Abort ();
}
}
}

Static void Main ()
{

Try
{
// Create a HttpWebrequest object to the desired URL.
HttpWebRequest myHttpWebRequest = (HttpWebRequest) WebRequest. Create ("http://www.contoso.com ");

/**
* If you are behind a firewall and you do not have your browser proxy setup
* You need to use the following proxy creation code.

// Create a proxy object.
WebProxy myProxy = new WebProxy ();

// Associate a new Uri object to the _ wProxy object, using the proxy address
// Selected by the user.
MyProxy. Address = new Uri ("http: // myproxy ");


// Finally, initialize the Web request object proxy property with the _ wProxy
// Object.
MyHttpWebRequest. Proxy = myProxy;
***/

// Create an instance of the RequestState and assign the previous myHttpWebRequest
// Object to it's request field.
RequestState myRequestState = new RequestState ();
MyRequestState. request = myHttpWebRequest;

// Start the asynchronous request.
IAsyncResult result =
(IAsyncResult) myHttpWebRequest. BeginGetResponse (new AsyncCallback (RespCallback), myRequestState );

// This line impliments the timeout, if there is a timeout, the callback fires and the request becomes aborted
ThreadPool. RegisterWaitForSingleObject (result. AsyncWaitHandle, new WaitOrTimerCallback (TimeoutCallback), myHttpWebRequest, DefaultTimeout, true );

// The response came in the allowed time. The work processing will happen in
// Callback function.
AllDone. WaitOne ();

// Release the HttpWebResponse resource.
MyRequestState. response. Close ();
}
Catch (WebException e)
{
Console. WriteLine ("\ nMain Exception raised! ");
Console. WriteLine ("\ nMessage: {0}", e. Message );
Console. WriteLine ("\ nStatus: {0}", e. Status );
Console. WriteLine ("Press any key to continue ..........");
}
Catch (Exception e)
{
Console. WriteLine ("\ nMain Exception raised! ");
Console. WriteLine ("Source: {0}", e. Source );
Console. WriteLine ("Message: {0}", e. Message );
Console. WriteLine ("Press any key to continue ..........");
Console. Read ();
}
}
Private static void RespCallback (IAsyncResult asynchronousResult)
{
Try
{
// State of request is asynchronous.
RequestState myRequestState = (RequestState) asynchronousResult. AsyncState;
HttpWebRequest myHttpWebRequest = myRequestState. request;
MyRequestState. response = (HttpWebResponse) myHttpWebRequest. EndGetResponse (asynchronousResult );

// Read the response into a Stream object.
Stream responseStream = myRequestState. response. GetResponseStream ();
MyRequestState. streamResponse = responseStream;

// Begin the Reading of the contents of the HTML page and print it to the console.
IAsyncResult asynchronousInputRead = responseStream. BeginRead (myRequestState. BufferRead, 0, BUFFER_SIZE, new AsyncCallback (ReadCallBack), myRequestState );
Return;
}
Catch (WebException e)
{
Console. WriteLine ("\ nRespCallback Exception raised! ");
Console. WriteLine ("\ nMessage: {0}", e. Message );
Console. WriteLine ("\ nStatus: {0}", e. Status );
}
AllDone. Set ();
}
Private static void ReadCallBack (IAsyncResult asyncResult)
{
Try
{

RequestState myRequestState = (RequestState) asyncResult. AsyncState;
Stream responseStream = myRequestState. streamResponse;
Int read = responseStream. EndRead (asyncResult );
// Read the HTML page and then print it to the console.
If (read> 0)
{
MyRequestState. requestData. Append (Encoding. ASCII. GetString (myRequestState. BufferRead, 0, read ));
IAsyncResult asynchronousResult = responseStream. BeginRead (myRequestState. BufferRead, 0, BUFFER_SIZE, new AsyncCallback (ReadCallBack), myRequestState );
Return;
}
Else
{
Console. WriteLine ("\ nThe contents of the Html page are :");
If (myRequestState. requestData. Length> 1)
{
String stringContent;
StringContent = myRequestState. requestData. ToString ();
Console. WriteLine (stringContent );
}
Console. WriteLine ("Press any key to continue ..........");
Console. ReadLine ();

ResponseStream. Close ();
}

}
Catch (WebException e)
{
Console. WriteLine ("\ nReadCallBack Exception raised! ");
Console. WriteLine ("\ nMessage: {0}", e. Message );
Console. WriteLine ("\ nStatus: {0}", e. Status );
}
AllDone. Set ();

}