Socket.BeginReceiveMessageFrom Method


Begins to asynchronously receive the specified number of bytes of data into the specified location of the data buffer, using the specified SocketFlags, and stores the endpoint and packet information.

 IAsyncResult ^ BeginReceiveMessageFrom(cli::array <System::Byte> ^ buffer, int offset, int size, System::Net::Sockets::SocketFlags socketFlags, System::Net::EndPoint ^ % remoteEP, AsyncCallback ^ callback, System::Object ^ state);
public IAsyncResult BeginReceiveMessageFrom (byte[] buffer, int offset, int size, System.Net.Sockets.SocketFlags socketFlags, ref System.Net.EndPoint remoteEP, AsyncCallback? callback, object? state);
public IAsyncResult BeginReceiveMessageFrom (byte[] buffer, int offset, int size, System.Net.Sockets.SocketFlags socketFlags, ref System.Net.EndPoint remoteEP, AsyncCallback callback, object state);
member this.BeginReceiveMessageFrom : byte[] * int * int * System.Net.Sockets.SocketFlags * EndPoint * AsyncCallback * obj -> IAsyncResult
Public Function BeginReceiveMessageFrom (buffer As Byte(), offset As Integer, size As Integer, socketFlags As SocketFlags, ByRef remoteEP As EndPoint, callback As AsyncCallback, state As Object) As IAsyncResult



An array of type Byte that is the storage location for the received data.


The zero-based position in the buffer parameter at which to store the data.


The number of bytes to receive.


A bitwise combination of the SocketFlags values.


A reference to an EndPoint of the same type as the endpoint of the remote host to be updated on synchronous receive.


The AsyncCallback delegate.


An object that contains state information for this request.


An IAsyncResult that references the asynchronous read.


buffer is null.


remoteEP is null.

.NET Framework and .NET 5 and earlier only: An error occurred when attempting to access the socket.

offset is less than 0.


offset is greater than the length of buffer.


size is less than 0.


size is greater than the length of buffer minus the value of the offset parameter.

The Socket has been closed.



This is a compatibility API. We don't recommend using the APM (Begin* and End*) methods for new development. Instead, use the Task-based equivalents.

You can pass a callback that implements AsyncCallback to BeginReceiveMessageFrom in order to get notified about the completion of the operation. Note that if the underlying network stack completes the operation synchronously, the callback will be executed inline, during the call to BeginReceiveMessageFrom. In this case, the CompletedSynchronously property on the returned IAsyncResult will be set to true to indicate that the method completed synchronously. Use the AsyncState property of the IAsyncResult to obtain the state object passed to the BeginReceiveMessageFrom method.

The asynchronous BeginReceiveMessageFrom operation must be completed by calling the EndReceiveMessageFrom method. Typically, the method is invoked by the AsyncCallback delegate. EndReceiveMessageFrom will block the calling thread until the operation is completed.

To cancel a pending BeginReceiveMessageFrom, call the Close method.

This method reads data into the buffer parameter, and captures the remote host endpoint from which the data is sent, as well as information about the received packet. For information on how to retrieve this endpoint, refer to EndReceiveMessageFrom. This method is most useful if you intend to asynchronously receive connectionless datagrams from an unknown host or multiple hosts.


If you receive a SocketException, use the SocketException.ErrorCode property to obtain the specific error code.


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


The execution context (the security context, the impersonated user, and the calling context) is cached for the asynchronous Socket methods. After the first use of a particular context (a specific asynchronous Socket method, a specific Socket instance, and a specific callback), subsequent uses of that context will see a performance improvement.

Applies to