/// <summary>
/// Initiates an asynchronous transfer.
/// </summary>
/// <param name="callback">The delegate to be called when the operation completes (or <c>null</c>).</param>
/// <param name="state">Application defined state (or <c>null</c>).</param>
/// <returns>The <see cref="IAsyncResult" /> to be used to track the operation.</returns>
/// <remarks>
/// <note>
/// For server sessions, passing <paramref name="callback" /> as <c>null</c> indicates
/// that the session will automatically call <see cref="EndTransfer" /> when the operation completes.
/// Applications that wish to track the transfer completion must pass a non-<c>null</c> callback.
/// </note>
/// </remarks>
public IAsyncResult BeginTransfer(AsyncCallback callback, object state)
{
if (started)
{
throw new InvalidOperationException("Cannot reuse a StreamTransferSession instance.");
}
started = true;
if (reliableSession.IsClient)
{
return(reliableSession.BeginTransfer(serverEP, direction, Helper.NewGuid(), 0, args, null, null));
}
// Server side transfers start automatically when the message
// handler returns.
arTransfer = new AsyncResult(null, callback, state);
arTransfer.Started();
return(arTransfer);
}
