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HttpWebRequest.EndGetResponse Method

.NET Framework 2.0

Other Versions

Ends an asynchronous request to an Internet resource.

Namespace: System.Net
Assembly: System (in system.dll)

Syntax

C++

Copy

public override WebResponse EndGetResponse (
	IAsyncResult asyncResult
)

Copy

public WebResponse EndGetResponse (
	IAsyncResult asyncResult
)

JScript

Copy

public override function EndGetResponse (
	asyncResult : IAsyncResult
) : WebResponse

Parameters

asyncResult: The pending request for a response.

Return Value

A WebResponse that contains the response from the Internet resource.

Exceptions

Exception type	Condition
ArgumentNullException	asyncResult is a null reference (Nothing in Visual Basic).
InvalidOperationException	This method was called previously using asyncResult. -or- The ContentLength property is greater than 0 but the data has not been written to the request stream.
WebException	Abort was previously called. -or- An error occurred while processing the request.
ArgumentException	asyncResult was not returned by the current instance from a call to BeginGetResponse.

Remarks

The EndGetResponse method completes an asynchronous request for an Internet resource that was started by calling the BeginGetResponse method.

Caution
You must call the Close method to close the stream and release the connection. Failure to do so may cause your application to run out of connections.

Note
This member outputs trace information when you enable network tracing in your application. For more information, see Network Tracing.

Example

The following code example uses the EndGetResponse method to end an asynchronous request for an Internet resource.

C++

Copy

  try
  {      

    
    // Create a HttpWebrequest object to the desired URL.
    HttpWebRequest myHttpWebRequest1= (HttpWebRequest)WebRequest.Create("http://www.contoso.com");
    
    // Create an instance of the RequestState and assign the previous myHttpWebRequest1
    // object to it's request field.  
    RequestState myRequestState = new RequestState();  
    myRequestState.request = myHttpWebRequest1;


    // Start the asynchronous request.
    IAsyncResult result=
      (IAsyncResult) myHttpWebRequest1.BeginGetResponse(new AsyncCallback(RespCallback),myRequestState);

    allDone.WaitOne();
    
    // Release the HttpWebResponse resource.
    myRequestState.response.Close();
  }
  catch(WebException e)
  {
    Console.WriteLine("\nException 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("\nException 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  myHttpWebRequest2=myRequestState.request;
    myRequestState.response = (HttpWebResponse) myHttpWebRequest2.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);
  }
  catch(WebException e)
  {
    Console.WriteLine("\nException raised!");
    Console.WriteLine("\nMessage:{0}",e.Message);
    Console.WriteLine("\nStatus:{0}",e.Status);
    
  }
}
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);
  }
  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();
    allDone.Set();
   
  }

  }
  catch(WebException e)
  {
    Console.WriteLine("\nException raised!");
    Console.WriteLine("\nMessage:{0}",e.Message);
    Console.WriteLine("\nStatus:{0}",e.Status);
    
  }

}

Copy

        try {
            // Create a HttpWebrequest object to the desired URL.
            HttpWebRequest myHttpWebRequest1 = ((HttpWebRequest)
                (WebRequest.Create("http://www.contoso.com")));
            // Create an instance of the RequestState and assign the 
            //previous myHttpWebRequest1
            // object to it's request field.  
            RequestState myRequestState = new RequestState();
            myRequestState.request = myHttpWebRequest1;
            // Start the asynchronous request.
            IAsyncResult result = (IAsyncResult)
                (myHttpWebRequest1.BeginGetResponse(new 
                AsyncCallback(RespCallback), myRequestState));
            allDone.WaitOne();
            // Release the HttpWebResponse resource.
            myRequestState.response.Close();
        }
        catch (WebException e) {
            Console.WriteLine("\nException raised!");
            Console.WriteLine("\nMessage:{0}", e.get_Message());
            Console.WriteLine("\nStatus:{0}", e.get_Status());
            Console.WriteLine("Press any key to continue..........");
        }
        catch (System.Exception e) {
            Console.WriteLine("\nException raised!");
            Console.WriteLine("Source :{0} ", e.get_Source());
            Console.WriteLine("Message :{0} ", e.get_Message());
            Console.WriteLine("Press any key to continue..........");
            Console.Read();
        }
    } //main

    private static void RespCallback(IAsyncResult asynchronousResult)
    {
        try {
            // State of request is asynchronous.
            RequestState myRequestState = (RequestState)
                (asynchronousResult.get_AsyncState());
            HttpWebRequest myHttpWebRequest2 = myRequestState.request;

            myRequestState.response = (HttpWebResponse)(myHttpWebRequest2.
                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);
        }
        catch (WebException e) {
            Console.WriteLine("\nException raised!");
            Console.WriteLine("\nMessage:{0}", e.get_Message());
            Console.WriteLine("\nStatus:{0}", e.get_Status());
        }
    } //RespCallback

    private static void ReadCallBack(IAsyncResult asyncResult)
    {
        try {
            RequestState myRequestState = (RequestState)
                (asyncResult.get_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.get_ASCII().
                    GetString(myRequestState.bufferRead, 0, read));
                IAsyncResult asynchronousResult = responseStream.BeginRead
                    (myRequestState.bufferRead, 0, BUFFER_SIZE, new 
                    AsyncCallback(ReadCallBack), myRequestState);
            }
            else {
                Console.WriteLine("\nThe contents of the Html page are : ");

                if (myRequestState.requestData.get_Length() > 1) {
                    String stringContent;
                    stringContent = myRequestState.requestData.ToString();
                    Console.WriteLine(stringContent);
                }
                Console.WriteLine("Press any key to continue..........");
                Console.ReadLine();
                responseStream.Close();
                allDone.Set();
            }
        }
        catch (WebException e) {
            Console.WriteLine("\nException raised!");
            Console.WriteLine("\nMessage:{0}", e.get_Message());
            Console.WriteLine("\nStatus:{0}", e.get_Status());
        }
    } //ReadCallBack
} //HttpWebRequest_BeginGetResponse

Platforms

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see System Requirements.

Version Information

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

Reference

HttpWebRequest Class
HttpWebRequest Members
System.Net Namespace

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