UdpClient.EndReceive(IAsyncResult, IPEndPoint) Method

Definition

Namespace:

System.Net.Sockets

Assembly:

System.Net.Sockets.dll

Source:

UDPClient.cs

Ends a pending asynchronous receive.

public:
 cli::array <System::Byte> ^ EndReceive(IAsyncResult ^ asyncResult, System::Net::IPEndPoint ^ % remoteEP);

public byte[] EndReceive (IAsyncResult asyncResult, ref System.Net.IPEndPoint? remoteEP);

member this.EndReceive : IAsyncResult * IPEndPoint -> byte[]

Public Function EndReceive (asyncResult As IAsyncResult, ByRef remoteEP As IPEndPoint) As Byte()

Parameters

asyncResult

IAsyncResult

An IAsyncResult object returned by a call to BeginReceive(AsyncCallback, Object).

remoteEP

IPEndPoint

The specified remote endpoint.

Returns

Byte[]

If successful, an array of bytes that contains datagram data.

Exceptions

ArgumentNullException

asyncResult is null.

ArgumentException

asyncResult was not returned by a call to the BeginReceive(AsyncCallback, Object) method.

InvalidOperationException

EndReceive(IAsyncResult, IPEndPoint) was previously called for the asynchronous read.

SocketException

An error occurred when attempting to access the underlying Socket.

ObjectDisposedException

The underlying Socket has been closed.

Examples

The following code example uses BeginSend to complete an asynchronous receive of a server response.

private:
    static int listenPort = 13000;

public:
    value struct UdpState
    {
    public:
        UdpClient^ udpClient;
        IPEndPoint^ ipEndPoint;
    };

    static bool isMessageReceived;

    static void ReceiveCallback(IAsyncResult^ asyncResult)
    {
        UdpClient^ udpClient =
            ((UdpState)(asyncResult->AsyncState)).udpClient;
        IPEndPoint^ ipEndPoint =
            ((UdpState)(asyncResult->AsyncState)).ipEndPoint;

        array<Byte>^ receiveBytes =
            udpClient->EndReceive(asyncResult, ipEndPoint);
        String^ receiveString =
            Encoding::ASCII->GetString(receiveBytes);

        Console::WriteLine("Received: {0}", receiveString);
        isMessageReceived = true;
    }

    static void ReceiveMessages()
    {
        // Receive a message and write it to the console.
        IPEndPoint^ ipEndPoint = gcnew IPEndPoint(IPAddress::Any, listenPort);
        UdpClient^ udpClient = gcnew UdpClient(ipEndPoint);

        UdpState^ udpState = gcnew UdpState();
        udpState->ipEndPoint = ipEndPoint;
        udpState->udpClient = udpClient;

        Console::WriteLine("listening for messages");
        udpClient->BeginReceive(gcnew AsyncCallback(ReceiveCallback),
            udpState);

        // Do some work while we wait for a message. For this example,
        // we'll just sleep
        while (!isMessageReceived)
        {
            Thread::Sleep(100);
        }
    }

public struct UdpState
{
    public UdpClient u;
    public IPEndPoint e;
}

public static bool messageReceived = false;

public static void ReceiveCallback(IAsyncResult ar)
{
    UdpClient u = ((UdpState)(ar.AsyncState)).u;
    IPEndPoint e = ((UdpState)(ar.AsyncState)).e;

    byte[] receiveBytes = u.EndReceive(ar, ref e);
    string receiveString = Encoding.ASCII.GetString(receiveBytes);

    Console.WriteLine($"Received: {receiveString}");
    messageReceived = true;
}

public static void ReceiveMessages()
{
    // Receive a message and write it to the console.
    IPEndPoint e = new IPEndPoint(IPAddress.Any, s_listenPort);
    UdpClient u = new UdpClient(e);

    UdpState s = new UdpState();
    s.e = e;
    s.u = u;

    Console.WriteLine("listening for messages");
    u.BeginReceive(new AsyncCallback(ReceiveCallback), s);

    // Do some work while we wait for a message. For this example, we'll just sleep
    while (!messageReceived)
    {
        Thread.Sleep(100);
    }
}

Remarks

This method blocks until the operation is complete.

To perform this operation synchronously, use the Receive method.