UdpClient.BeginSend Method (Byte[], Int32, String, Int32, AsyncCallback, Object)

 
System_CAPS_noteNote

The .NET API Reference documentation has a new home. Visit the .NET API Browser on docs.microsoft.com to see the new experience.

Sends a datagram to a destination asynchronously. The destination is specified by the host name and port number.

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

[HostProtectionAttribute(SecurityAction.LinkDemand, ExternalThreading = true)]
public IAsyncResult BeginSend(
	byte[] datagram,
	int bytes,
	string hostname,
	int port,
	AsyncCallback requestCallback,
	object state
)

Parameters

datagram
Type: System.Byte[]

A Byte array that contains the data to be sent.

bytes
Type: System.Int32

The number of bytes to send.

hostname
Type: System.String

The destination host.

port
Type: System.Int32

The destination port number.

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 send 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 send.

The asynchronous BeginSend operation must be completed by calling the EndSend method. Typically, the method is invoked by the requestCallback delegate.

This method does not block until the operation is complete. To block until the operation is complete, use one of the Send method overloads.

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

The following code example uses BeginSend to asynchronously send a server request.

public static bool messageSent = false;

public static void SendCallback(IAsyncResult ar)
{
  UdpClient u = (UdpClient)ar.AsyncState;

  Console.WriteLine("number of bytes sent: {0}", u.EndSend(ar));
  messageSent = true;
}
static void SendMessage3(string server, string message)
{
  // create the udp socket
  UdpClient u = new UdpClient();

  Byte [] sendBytes = Encoding.ASCII.GetBytes(message);

  // send the message
  // the destination is defined by the server name and port
  u.BeginSend(sendBytes, sendBytes.Length, server, listenPort,
              new AsyncCallback(SendCallback), u);

  // Do some work while we wait for the send to complete. For 
  // this example, we'll just sleep
  while (!messageSent)
  {
    Thread.Sleep(100);
  }
}

.NET Framework
Available since 2.0
Return to top
Show: