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HttpWebRequest.KeepAlive Property

Gets or sets a value indicating whether to make a persistent connection to the Internet resource.

[Visual Basic]
Public Property KeepAlive As Boolean
[C#]
public bool KeepAlive {get; set;}
[C++]
public: __property bool get_KeepAlive();
public: __property void set_KeepAlive(bool);
[JScript]
public function get KeepAlive() : Boolean;
public function set KeepAlive(Boolean);

Property Value

true if the request to the Internet resource should contain a Connection HTTP header with the value Keep-alive; otherwise, false. The default is true.

Remarks

Set this property to true to send an Connection HTTP header with the value Keep-alive. An application uses KeepAlive to indicate a preference for persistent connections. When the KeepAlive property is true, the application makes persistent connections to the servers that support them.

Note   When using HTTP/1.1, Keep-Alive is on by default. Setting KeepAlive false may result in sending a Connection: Close header to the server.

Example

[Visual Basic, C#, C++] The following example sets the KeepAlive property to false to avoid establishing a persistent connection with the internet resource.

[Visual Basic] 

Class HttpWebRequest_Connection
  
  Shared Sub Main()
    Try

      ' Create a new 'HttpWebRequest' object for the specified Uri. Make sure that 
      ' a default proxy is set if you are behind a fure wall.
      Dim myHttpWebRequest1 As HttpWebRequest = CType(WebRequest.Create("http://www.contoso.com"), HttpWebRequest)
      myHttpWebRequest1.KeepAlive = False
      ' Assign the response object of 'HttpWebRequest' to a 'HttpWebResponse' variable.
      Dim myHttpWebResponse1 As HttpWebResponse = CType(myHttpWebRequest1.GetResponse(), HttpWebResponse)

      Console.WriteLine(ControlChars.Cr + "The HTTP request Headers for the first request are {0}", myHttpWebRequest1.Headers)
      Console.WriteLine("Press Enter Key to Continue..........")
      Console.Read()
      Dim streamResponse As Stream = myHttpWebResponse1.GetResponseStream()
      Dim streamRead As New StreamReader(streamResponse)
      Dim readBuff(256) As [Char]
      Dim count As Integer = streamRead.Read(readBuff, 0, 256)
      Console.WriteLine("The contents of the Html page are......." + ControlChars.Cr)
      While count > 0
        Dim outputData As New [String](readBuff, 0, count)
        Console.Write(outputData)
        count = streamRead.Read(readBuff, 0, 256)
      End While
      ' Close the Stream object.
      streamResponse.Close()
      streamRead.Close()
     ' Release the resources held by response object.
      myHttpWebResponse1.Close()
      Console.WriteLine()
     ' Create a new 'HttpWebRequest' object  to the specified Uri.   
      Dim myHttpWebRequest2 As HttpWebRequest = CType(WebRequest.Create("http://www.contoso.com"), HttpWebRequest)
      myHttpWebRequest2.Connection = "Close"
      ' Assign the response object of 'HttpWebRequest' to a 'HttpWebResponse' variable.
      Dim myHttpWebResponse2 As HttpWebResponse = CType(myHttpWebRequest2.GetResponse(), HttpWebResponse)
    ' Release the resources held by response object.
    myHttpWebResponse2.Close()
      Console.WriteLine(ControlChars.Cr + "The Http RequestHeaders are " + ControlChars.Cr + "{0}", myHttpWebRequest2.Headers)
      Console.WriteLine(ControlChars.Cr + "Press 'Enter' Key to Continue.........")
      Console.Read()
    Catch e As ArgumentException
      Console.WriteLine(ControlChars.Cr + "The second HttpWebRequest object has raised an Argument Exception as 'Connection' Property is set to 'Close'")
      Console.WriteLine(ControlChars.Cr + "{0}", e.Message)
    Catch e As WebException
      Console.WriteLine("WebException raised!")
      Console.WriteLine(ControlChars.Cr + "{0}", e.Message)
      Console.WriteLine(ControlChars.Cr + "{0}", e.Status)
    Catch e As Exception
      Console.WriteLine("Exception raised!")
      Console.WriteLine("Source :{0} ", e.Source)
      Console.WriteLine("Message : {0}", e.Message)
    End Try
  End Sub ' Main
End Class ' HttpWebRequest_Connection

[C#] 

using System;
using System.IO;
using System.Net;
using System.Text;


class HttpWebRequest_Connection
{
  static void Main()
  {    
    try  
    {

      // Create a new HttpWebRequest object.Make sure that 
      // a default proxy is set if you are behind a fure wall.
      HttpWebRequest myHttpWebRequest1 =
        (HttpWebRequest)WebRequest.Create("http://www.contoso.com");
     
      myHttpWebRequest1.KeepAlive=false;
      // Assign the response object of HttpWebRequest to a HttpWebResponse variable.
      HttpWebResponse myHttpWebResponse1 = 
        (HttpWebResponse)myHttpWebRequest1.GetResponse();

      Console.WriteLine("\nThe HTTP request Headers for the first request are: \n{0}",myHttpWebRequest1.Headers);
      Console.WriteLine("Press Enter Key to Continue..........");
      Console.Read();

      Stream streamResponse=myHttpWebResponse1.GetResponseStream();
      StreamReader streamRead = new StreamReader( streamResponse );
      Char[] readBuff = new Char[256];
      int count = streamRead.Read( readBuff, 0, 256 );
      Console.WriteLine("The contents of the Html page are.......\n");  
      while (count > 0) 
      {
        String outputData = new String(readBuff, 0, count);
        Console.Write(outputData);
        count = streamRead.Read(readBuff, 0, 256);
      }
      Console.WriteLine();
      // Close the Stream object.
      streamResponse.Close();
      streamRead.Close();
      // Release the resources held by response object.
      myHttpWebResponse1.Close();
      // Create a new HttpWebRequest object for the specified Uri.
      HttpWebRequest myHttpWebRequest2 = 
        (HttpWebRequest)WebRequest.Create("http://www.contoso.com");
      myHttpWebRequest2.Connection="Close";
      // Assign the response object of 'HttpWebRequest' to a 'HttpWebResponse' variable.
      HttpWebResponse myHttpWebResponse2 = 
        (HttpWebResponse)myHttpWebRequest2.GetResponse();
      // Release the resources held by response object.
      myHttpWebResponse2.Close();
      Console.WriteLine("\nThe Http RequestHeaders are \n{0}",myHttpWebRequest2.Headers);
      Console.WriteLine("\nPress 'Enter' Key to Continue.........");
      Console.Read();      
    }
    catch(ArgumentException e)
    {
      Console.WriteLine("\nThe second HttpWebRequest object has raised an Argument Exception as 'Connection' Property is set to 'Close'");
      Console.WriteLine("\n{0}",e.Message);
    }
    catch(WebException e)
    {
      Console.WriteLine("WebException raised!");
      Console.WriteLine("\n{0}",e.Message);
      Console.WriteLine("\n{0}",e.Status);
    } 
    catch(Exception e)
    {
      Console.WriteLine("Exception raised!");
      Console.WriteLine("Source :{0} " , e.Source);
      Console.WriteLine("Message :{0} " , e.Message);
    }
  }
}


[C++] 
int main() {
   try {

      // Create a new HttpWebRequest object.  Make sure that
      // a default proxy is set if you are behind a firewall.
      HttpWebRequest* myHttpWebRequest1 =
         dynamic_cast<HttpWebRequest*>(WebRequest::Create(S"http://www.contoso.com"));

      myHttpWebRequest1->KeepAlive=false;
      // Assign the response object of HttpWebRequest to a HttpWebResponse variable.
      HttpWebResponse* myHttpWebResponse1 =
         dynamic_cast<HttpWebResponse*>(myHttpWebRequest1->GetResponse());

      Console::WriteLine(S"\nThe HTTP request Headers for the first request are: \n {0}",
         myHttpWebRequest1->Headers);
      Console::WriteLine(S"Press Enter Key to Continue..........");
      Console::Read();

      Stream* streamResponse = myHttpWebResponse1->GetResponseStream();
      StreamReader* streamRead = new StreamReader(streamResponse);
      Char readBuff[] = new Char[256];
      int count = streamRead->Read(readBuff, 0, 256);
      Console::WriteLine(S"The contents of the Html page are.......\n");
      while (count > 0) {
         String* outputData = new String(readBuff, 0, count);
         Console::Write(outputData);
         count = streamRead->Read(readBuff, 0, 256);
      }
      Console::WriteLine();
      // Close the Stream object.
      streamResponse->Close();
      streamRead->Close();
      // Release the resources held by response object.
      myHttpWebResponse1->Close();
      // Create a new HttpWebRequest object for the specified Uri.
      HttpWebRequest* myHttpWebRequest2 =
         dynamic_cast<HttpWebRequest*>(WebRequest::Create(S"http://www.contoso.com"));
      myHttpWebRequest2->Connection=S"Close";
      // Assign the response object of 'HttpWebRequest' to a 'HttpWebResponse' variable.
      HttpWebResponse* myHttpWebResponse2 =
         dynamic_cast<HttpWebResponse*>(myHttpWebRequest2->GetResponse());
      // Release the resources held by response object.
      myHttpWebResponse2->Close();
      Console::WriteLine(S"\nThe Http RequestHeaders are \n {0}",
         myHttpWebRequest2->Headers);
      Console::WriteLine(S"\nPress 'Enter' Key to Continue.........");
      Console::Read();
   } catch (ArgumentException* e) {
      Console::WriteLine(S"\nThe second HttpWebRequest Object* has raised an Argument Exception as 'Connection' Property is set to 'Close'");
      Console::WriteLine(S"\n {0}", e->Message);
   } catch (WebException* e) {
      Console::WriteLine(S"WebException raised!");
      Console::WriteLine(S"\n {0}", e->Message);
      Console::WriteLine(S"\n {0}", __box( e->Status));
   } catch (Exception* e) {
      Console::WriteLine(S"Exception raised!");
      Console::WriteLine(S"Source : {0} " , e->Source);
      Console::WriteLine(S"Message : {0} " , e->Message);
   }
}

[JScript] No example is available for JScript. To view a Visual Basic, C#, or C++ example, click the Language Filter button Language Filter in the upper-left corner of the page.

Requirements

Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family, .NET Compact Framework, Common Language Infrastructure (CLI) Standard

See Also

HttpWebRequest Class | HttpWebRequest Members | System.Net Namespace

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