public IoFuture<Void> sendData(final ByteBuffer data) {
if (sender == null) {
this.sender = exchange.getResponseSender();
}
final FutureResult<Void> future = new FutureResult<Void>();
sender.send(data, new IoCallback() {
@Override
public void onComplete(final HttpServerExchange exchange, final Sender sender) {
future.setResult(null);
}