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HttpWebRequest.EndGetResponse Method

Ends an asynchronous request to an Internet resource.

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

'Declaration
Public Overrides Function EndGetResponse ( _
	asyncResult As IAsyncResult _
) As WebResponse
'Usage
Dim instance As HttpWebRequest
Dim asyncResult As IAsyncResult
Dim returnValue As WebResponse

returnValue = instance.EndGetResponse(asyncResult)
public WebResponse EndGetResponse (
	IAsyncResult asyncResult
)
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.

Exception typeCondition

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.

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

Caution noteCaution

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.

NoteNote

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

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

  Try
    ' Create a new HttpWebrequest object to the desired URL.
    Dim myHttpWebRequest1 As HttpWebRequest = CType(WebRequest.Create("http://www.contoso.com"), HttpWebRequest)
    
    ' Create an instance of the RequestState and assign the previous myHttpWebRequest1
    ' object to it's request field.  
    Dim myRequestState As New RequestState()
    myRequestState.request = myHttpWebRequest1
    
    ' Start the Asynchronous request.
    Dim result As IAsyncResult = CType(myHttpWebRequest1.BeginGetResponse(AddressOf RespCallback, myRequestState), IAsyncResult)
    allDone.WaitOne()
  
    ' Release the HttpWebResponse resource.
    myRequestState.response.Close()
  Catch e As WebException
    Console.WriteLine(ControlChars.Cr + "Exception raised!")
    Console.WriteLine(ControlChars.Cr + "Message:{0}", e.Message)
    Console.WriteLine(ControlChars.Cr + "Status:{0}", e.Status)
    Console.WriteLine("Press any key to continue..........")
  
  Catch e As Exception
    Console.WriteLine(ControlChars.Cr + "Exception raised!")
    Console.WriteLine("Source :{0} ", e.Source)
    Console.WriteLine("Message : {0}", e.Message)
    Console.WriteLine("Press any key to continue..........")
    Console.Read()
  End Try
End Sub ' Main

Private Shared Sub RespCallback(asynchronousResult As IAsyncResult)
  Try
    ' State of request is asynchronous.
    Dim myRequestState As RequestState = CType(asynchronousResult.AsyncState, RequestState)
    Dim myHttpWebRequest2 As HttpWebRequest = myRequestState.request
    myRequestState.response = CType(myHttpWebRequest2.EndGetResponse(asynchronousResult), HttpWebResponse)
    ' Read the response into a Stream object.
    Dim responseStream As Stream = myRequestState.response.GetResponseStream()
    myRequestState.streamResponse = responseStream
    ' Begin the Reading of the contents of the HTML page and print it to the console.
    Dim asynchronousInputRead As IAsyncResult = responseStream.BeginRead(myRequestState.BufferRead, 0, BUFFER_SIZE, AddressOf ReadCallBack, myRequestState)
  Catch e As WebException
    Console.WriteLine(ControlChars.Cr + "Exception raised!")
    Console.WriteLine(ControlChars.Cr + "Message:{0}", e.Message)
    Console.WriteLine(ControlChars.Cr + "Status:{0}", e.Status)
  End Try 
End Sub ' RespCallback

Private Shared Sub ReadCallBack(asyncResult As IAsyncResult)
  Try
    Dim myRequestState As RequestState = CType(asyncResult.AsyncState, RequestState)
    Dim responseStream As Stream = myRequestState.streamResponse
    Dim read As Integer = responseStream.EndRead(asyncResult)
    '  Read the HTML page and then print it to the console.
    If read > 0 Then
      myRequestState.requestData.Append(Encoding.ASCII.GetString(myRequestState.BufferRead, 0, read))
      Dim asynchronousResult As IAsyncResult = responseStream.BeginRead(myRequestState.BufferRead, 0, BUFFER_SIZE, AddressOf ReadCallBack, myRequestState)
    Else
      Console.WriteLine(ControlChars.Cr + "The contents of the Html page are : ")
      If myRequestState.requestData.Length > 1 Then
        Dim stringContent As String
        stringContent = myRequestState.requestData.ToString()
        Console.WriteLine(stringContent)
      End If
      Console.WriteLine("Press any key to continue..........")
      Console.ReadLine()
      responseStream.Close()
      allDone.Set()
    End If
  Catch e As WebException
    Console.WriteLine(ControlChars.Cr + "Exception raised!")
    Console.WriteLine(ControlChars.Cr + "Message:{0}", e.Message)
    Console.WriteLine(ControlChars.Cr + "Status:{0}", e.Status)
  End Try 
End Sub ' ReadCallBack

        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

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.

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

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