Socket.SendToAsync Method

Syntax

'Declaration
Public Function SendToAsync ( _
    e As SocketAsyncEventArgs _
) As Boolean

public bool SendToAsync(
    SocketAsyncEventArgs e
)

Exceptions

Remarks

The SendToAsync(SocketAsyncEventArgs) method starts an asynchronous send operation to the remote host specified in the RemoteEndPoint property of the e parameter. Calling the SendToAsync(SocketAsyncEventArgs) method gives you the ability to send data within a separate execution thread. Although this method is intended for connectionless sockets of type Dgram, the SendToAsync(SocketAsyncEventArgs) method also works with connection-oriented sockets of type Stream.

To be notified of completion, you must create a callback method that implements the EventHandler<SocketAsyncEventArgs> delegate and attach the callback to the SocketAsyncEventArgs.Completed event.

The following properties and events on the System.Net.Sockets.SocketAsyncEventArgs object are required to successfully call this method:

• SocketAsyncEventArgs.Buffer

• SocketAsyncEventArgs.Count

• SocketAsyncEventArgs.Offset

• SocketAsyncEventArgs.RemoteEndPoint

• SocketAsyncEventArgs.Completed

The caller may set the SocketAsyncEventArgs.UserToken property to any user state object desired before calling the SendToAsync method, so that the information will be retrievable in the callback method. If the callback needs more information than a single object, a small class can be created to hold the other required state information as members.

If you are using a connection-oriented socket of type Stream, you must first call the ConnectAsync method. Otherwise SendToAsync will throw a SocketException. When using a connection-oriented socket of type Stream, the SendToAsync method will ignore the SocketAsyncEventArgs.RemoteEndPoint property and send data to the System.Net.EndPoint established in the ConnectAsync method.

If you are using a connectionless socket of type Dgram, you do not need to establish a default remote host with the ConnectAsync method prior to calling SendToAsync. You only need to do this if you intend to call the SendAsync method. If you do call the ConnectAsync method prior to calling SendToAsync, the SocketAsyncEventArgs.RemoteEndPoint property will override the specified default remote host for that send operation only.

For a message-oriented socket of type Dgram, care must be taken not to exceed the maximum message size of the underlying transport. If the size of the buffer exceeds the maximum packet size of the underlying service provider, the datagram is not sent and SendToAsync will throw a SocketException. The successful completion of a SendToAsync method does not indicate that the data was successfully delivered to the remote host. A successful completion only indicates that the data was successfully sent on the network from the local computer.

Note:
If you receive a SocketException when calling this method, use the SocketException.ErrorCode property to obtain the specific error code. After you have obtained this code, refer to the Windows Sockets Error Codes documentation in the MSDN library for a detailed description of the error.

Version Notes

Version Information

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1

Platforms

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

See Also

Reference