code: public void startUp() throws Exception {
      logger.info(String.format("Starting RPC server on port %d", port));
      ServerBootstrap bootstrap = new ServerBootstrap();
  
      ChannelFuture futureChannel = bootstrap.group(parentGroup, childGroup)
          .channel(channelClass)
          .childHandler(channelInitializer())
          .bind(port)
          .awaitUninterruptibly();
  
      if (futureChannel.isSuccess()) {
        this.channel = futureChannel.channel();
        logger.info("RPC server started successfully.");
      } else {
        logger.info("Failed to start RPC server.");
        throw new Exception(futureChannel.cause());
      }
    }
docs: Starts this server.
  <p/>
  <p>This is a synchronous operation.</p>