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PowerTCP SSL Sockets for .NET |
| Dart.PowerTCP.SslSockets Namespace > Udp Class > BeginReceive Method : BeginReceive(Byte[]) Method |
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PowerTCP SSL Sockets for .NET |
| Dart.PowerTCP.SslSockets Namespace > Udp Class > BeginReceive Method : BeginReceive(Byte[]) Method |
Asynchronously receive a datagram.
[Visual Basic]
<DescriptionAttribute("Receive datagram into your buffer asynchronously. The EndReceive event is raised when completed.")>
Overloads Public Function BeginReceive( _
ByVal buffer() As Byte _
) As IAsyncResult[C#]
[DescriptionAttribute("Receive datagram into your buffer asynchronously. The EndReceive event is raised when completed.")]
public IAsyncResult BeginReceive(
byte[] buffer
);[C++]
[DescriptionAttribute("Receive datagram into your buffer asynchronously. The EndReceive event is raised when completed.")]
public: IAsyncResult* BeginReceive(
byte[]* buffer
) [C++/CLI]
[DescriptionAttribute("Receive datagram into your buffer asynchronously. The EndReceive event is raised when completed.")]
public:
IAsyncResult^ BeginReceive(
bytearray<buffer>^ buffer
) An IAsyncResult that represents the asynchronous receive, which could still be pending.
| Exception | Description |
|---|---|
| ArgumentNullException | buffer is null. |
| InvalidOperationException | BeginXXX method used without providing an EndXXX event handler. |
Use the Receive method to asynchronously receive a datagram after first calling Open to specify a port/address to listen for datagrams. When the Udp.BeginReceive method has completed, the EndReceive event is raised. Made accessible in the EndReceive event is a Datagram object representing the datagram received. Buffer contains the actual datagram data. RemoteEndPoint contains the address/port of the remote host from which the datagram was sent.
To synchronously receive a datagram, use Receive.
A UDP datagram provides little functionality over an IP datagram, adding a port number field which allows multiplexing on the receiving host and checksum field which provides basic error handling. Unlike TCP, UDP datagrams are sent as a unit. If BeginSend is called 3 times to send 3 datagrams to a host, the receiving host will have to call Udp.BeginReceive 3 times. Also, the of each datagram sent will equal the size of each datagram received by the receiving host. In addition, since UDP is a connectionless protocol, any datagrams sent to the host are not guaranteed to be delivered. Therefore, any required error checking (outside of UDP's checksum implementation) will have to be done by the application-layer protocol.
The following example demonstrates creating a UDP echo server application which listens for datagrams and echoes them back to the sender.
[Visual Basic]
Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
' Listen for datagrams on port 7.
Udp1.Open(7)
' Begin an asynchronous Receive
Dim buffer(Udp1.BufferSize) As Byte
Udp1.BeginReceive(buffer)
End Sub
Private Sub Udp1_EndReceive(ByVal sender As Object, ByVal e As DatagramEventArgs) Handles Udp1.EndReceive
' Check for an Exception
If e.Exception is Nothing Then
' Echo the data back using the Datagram object passed into the event.
' Datagram.Buffer = data received from client
' Datagram.RemoteEndPoint = address/port of client.
Udp1.Send(e.Datagram.Buffer, e.Datagram.RemoteEndPoint)
End If
' Start receiving next
Dim buffer(Udp1.BufferSize) As Byte
Udp1.BeginReceive(buffer)
End Sub
[C#]
private void StartServer()
{
// Listen for datagrams on port 7.
udp1.Open(7);
// Begin an asynchronous Receive
byte[] buffer = new byte[udp1.BufferSize];
udp1.BeginReceive(buffer);
}
private void udp1_EndReceive(object
sender, DatagramEventArgs e)
{
// Check for an exception
if(e.Exception == null)
{
// Echo the data back using the Datagram object passed into the event.
// Datagram.Buffer = data received from client
// Datagram.RemoteEndPoint = address/port of client.
Datagram d = udp1.Send(e.Datagram.Buffer, e.Datagram.RemoteEndPoint);
}
// Start receiving next
byte[] buffer = new byte[udp1.BufferSize];
udp1.BeginReceive(buffer);
}
Platforms: Windows 98, Windows NT 4.0, Windows Millennium Edition, Windows 2000, Windows XP Home Edition, Windows XP Professional, Windows Server 2003 family
Udp Class | Udp Members | Overload List
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Documentation version 1.1.2.0.
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