Begins an asynchronous operation to accept an incoming connection attempt.
Assembly: System (in System.dll)
'Declaration <HostProtectionAttribute(SecurityAction.LinkDemand, ExternalThreading := True)> _ Public Function BeginAcceptTcpClient ( _ callback As AsyncCallback, _ state As Object _ ) As IAsyncResult
- Type: System.AsyncCallback
An AsyncCallback delegate that references the method to invoke when the operation is complete.
- Type: System.Object
A user-defined object containing information about the accept operation. This object is passed to the callback delegate when the operation is complete.
The asynchronous operation must be completed by calling the EndAcceptTcpClient method. Typically, the method is invoked by the callback delegate.
This method does not block until the operation completes. To block until the operation completes, use the AcceptTcpClient method.
For detailed information about using the asynchronous programming model, see Calling Synchronous Methods Asynchronously.
If you receive a SocketException, use the SocketException.ErrorCode property to obtain the specific error code and refer to the Windows Sockets version 2 API error code documentation in the MSDN library at http://msdn.microsoft.com/library/ for a detailed description of the error.
This member outputs trace information when you enable network tracing in your application. For more information, see Network Tracing.
The HostProtectionAttribute attribute applied to this type or member has the following Resources property value: ExternalThreading. The HostProtectionAttribute does not affect desktop applications (which are typically started by double-clicking an icon, typing a command, or entering a URL in a browser). For more information, see the HostProtectionAttribute class or SQL Server Programming and Host Protection Attributes.
The following code example demonstrates the use of the method to create and connect a socket. The callback delegate calls the EndAcceptTcpClient method to end the asynchronous request.
' Thread signal. Public Shared tcpClientConnected As New ManualResetEvent(False) ' Accept one client connection asynchronously. Public Shared Sub DoBeginAcceptTcpClient(listener As TcpListener) ' Set the event to nonsignaled state. tcpClientConnected.Reset() ' Start to listen for connections from a client. Console.WriteLine("Waiting for a connection...") ' Accept the connection. ' BeginAcceptSocket() creates the accepted socket. listener.BeginAcceptTcpClient(New AsyncCallback(AddressOf DoAcceptTcpClientCallback), listener) ' Wait until a connection is made and processed before ' continuing. tcpClientConnected.WaitOne() End Sub 'DoBeginAcceptTcpClient ' Process the client connection. Public Shared Sub DoAcceptTcpClientCallback(ar As IAsyncResult) ' Get the listener that handles the client request. Dim listener As TcpListener = CType(ar.AsyncState, TcpListener) ' End the operation and display the received data on ' the console. Dim client As TcpClient = listener.EndAcceptTcpClient(ar) ' Process the connection here. (Add the client to a ' server table, read data, etc.) Console.WriteLine("Client connected completed") ' Signal the calling thread to continue. tcpClientConnected.Set() End Sub 'DoAcceptTcpClientCallback
Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)