TcpListener.BeginAcceptSocket Method

Begins an asynchronous operation to accept an incoming connection attempt.

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

[HostProtectionAttribute(SecurityAction.LinkDemand, ExternalThreading = true)]
public IAsyncResult BeginAcceptSocket(
	AsyncCallback callback,
	Object state
)

Parameters

callback
Type: System.AsyncCallback

An AsyncCallback delegate that references the method to invoke when the operation is complete.

state
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.

Return Value

Type: System.IAsyncResult
An IAsyncResult that references the asynchronous creation of the Socket.

ExceptionCondition
SocketException

An error occurred while attempting to access the socket. See the Remarks section for more information.

ObjectDisposedException

The Socket has been closed.

The asynchronous BeginAcceptSocket operation must be completed by calling the EndAcceptSocket 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 AcceptSocket method.

For detailed information about using the asynchronous programming model, see Calling Synchronous Methods Asynchronously.

NoteNote

You can call the RemoteEndPoint property of the returned Socket to identify the remote host's network address and port number.

NoteNote

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.

NoteNote

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

NoteNote

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 BeginAcceptSocket method to create and connect a socket. The callback delegate calls the EndAcceptSocket method to end the asynchronous request.

// Thread signal. 
public static ManualResetEvent clientConnected = 
    new ManualResetEvent(false);

// Accept one client connection asynchronously. 
public static void DoBeginAcceptSocket(TcpListener listener)
{
    // Set the event to nonsignaled state.
    clientConnected.Reset();

    // Start to listen for connections from a client.
    Console.WriteLine("Waiting for a connection...");

    // Accept the connection.  
    // BeginAcceptSocket() creates the accepted socket.
    listener.BeginAcceptSocket(
        new AsyncCallback(DoAcceptSocketCallback), listener);
    // Wait until a connection is made and processed before  
    // continuing.
    clientConnected.WaitOne();
}

// Process the client connection. 
public static void DoAcceptSocketCallback(IAsyncResult ar) 
{
    // Get the listener that handles the client request.
    TcpListener listener = (TcpListener) ar.AsyncState;

    // End the operation and display the received data on the 
    //console.
    Socket clientSocket = listener.EndAcceptSocket(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.
    clientConnected.Set();
}

.NET Framework

Supported in: 4.5.2, 4.5.1, 4.5, 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

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)

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

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