TcpClient.BeginConnect Method (String, Int32, AsyncCallback, Object) (System.Net.Sockets)

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.NET Framework Class Library

TcpClient.BeginConnect Method (String, Int32, AsyncCallback, Object)

Begins an asynchronous request for a remote host connection. The remote host is specified by a host name (String) and a port number (Int32).

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

Syntax

Visual Basic

<HostProtectionAttribute(SecurityAction.LinkDemand, ExternalThreading := True)> _
Public Function BeginConnect ( _
	host As String, _
	port As Integer, _
	requestCallback As AsyncCallback, _
	state As Object _
) As IAsyncResult

[HostProtectionAttribute(SecurityAction.LinkDemand, ExternalThreading = true)]
public IAsyncResult BeginConnect(
	string host,
	int port,
	AsyncCallback requestCallback,
	Object state
)

Visual C++

[HostProtectionAttribute(SecurityAction::LinkDemand, ExternalThreading = true)]
public:
IAsyncResult^ BeginConnect(
	String^ host, 
	int port, 
	AsyncCallback^ requestCallback, 
	Object^ state
)

[<HostProtectionAttribute(SecurityAction.LinkDemand, ExternalThreading = true)>]
member BeginConnect : 
        host:string * 
        port:int * 
        requestCallback:AsyncCallback * 
        state:Object -> IAsyncResult

Parameters

host: Type: System.String
The name of the remote host.

port: Type: System.Int32
The port number of the remote host.

requestCallback: 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 that contains information about the connect operation. This object is passed to the requestCallback delegate when the operation is complete.

Return Value

Type: System.IAsyncResult
An IAsyncResult object that references the asynchronous connection.

Exceptions

Exception	Condition
ArgumentNullException	The host parameter is null.
SocketException	An error occurred when attempting to access the socket. See the Remarks section for more information.
ObjectDisposedException	The Socket has been closed.
SecurityException	A caller higher in the call stack does not have permission for the requested operation.
ArgumentOutOfRangeException	The port number is not valid.

Remarks

The asynchronous BeginConnect operation must be completed by calling the EndConnect method. Typically, the method is invoked by the asyncCallback delegate.

This method does not block until the operation completes. To block until the operation completes, use one of the Connect method overloads.

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

Note
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.

Note

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.

Examples

The following code example creates a TcpClient and connects to a remote host.

Visual Basic


' Connect asynchronously to the specifed host.
Public Shared Sub DoBeginConnect3(ByVal host As String, ByVal port As Integer)
    Dim t As New TcpClient(AddressFamily.InterNetwork)

    connectDone.Reset()

    Console.WriteLine("Establishing Connection to {0}", host)
    t.BeginConnect(host, port, New AsyncCallback(AddressOf ConnectCallback), t)

    ' Wait here until the callback processes the connection.
    connectDone.WaitOne()

    Console.WriteLine("Connection established")
End Sub


// Connect asynchronously to the specifed host.
public static void DoBeginConnect3(string host, int port)
{
    TcpClient t = new TcpClient(AddressFamily.InterNetwork);

    connectDone.Reset();

    Console.WriteLine("Establishing Connection to {0}", 
        host);
    t.BeginConnect(host, port, 
        new AsyncCallback(ConnectCallback), t);

    // Wait here until the callback processes the connection.
    connectDone.WaitOne();

    Console.WriteLine("Connection established");
}

Visual C++


// Connect asynchronously to the specifed host.
static void DoBeginConnect3( String^ host, int port )
{
   TcpClient^ t = gcnew TcpClient( AddressFamily::InterNetwork );
   connectDone->Reset();
   Console::WriteLine( "Establishing Connection to {0}", host );
   t->BeginConnect( host, port, gcnew AsyncCallback(  &ConnectCallback ), t );

   // Wait here until the callback processes the connection.
   connectDone->WaitOne();
   Console::WriteLine( "Connection established" );
}

Version Information

.NET Framework

Supported in: 4, 3.5, 3.0, 2.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Platforms

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows XP SP2 x64 Edition, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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

Reference

TcpClient Class

BeginConnect Overload

System.Net.Sockets Namespace