try-netty/server/src/main/java/com/miti99/netty/Main.java

package com.miti99.netty;

import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.Channel;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.epoll.Epoll;
import io.netty.channel.epoll.EpollEventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.http.HttpObjectAggregator;
import io.netty.handler.codec.http.HttpServerCodec;
import io.netty.handler.codec.http.websocketx.WebSocketServerProtocolHandler;
import io.netty.handler.codec.http.websocketx.extensions.compression.WebSocketServerCompressionHandler;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import io.netty.util.internal.logging.InternalLoggerFactory;
import io.netty.util.internal.logging.Slf4JLoggerFactory;
import lombok.extern.slf4j.Slf4j;
import lombok.val;

@Slf4j
public class Main {

  public static void main(String[] args) {
    InternalLoggerFactory.setDefaultFactory(Slf4JLoggerFactory.INSTANCE);
    var parentGroup = Epoll.isAvailable() ? new EpollEventLoopGroup() : new NioEventLoopGroup();
    var childGroup = Epoll.isAvailable() ? new EpollEventLoopGroup() : new NioEventLoopGroup();

    val serverBootstrap = new ServerBootstrap();
    serverBootstrap.group(parentGroup, childGroup).channel(
            NioServerSocketChannel.class
        ).handler(new LoggingHandler(LogLevel.DEBUG))
        .childHandler(new ChannelInitializer<>() {

          @Override
          protected void initChannel(Channel channel) {
            channel.pipeline()
                .addLast(new LoggingHandler(LogLevel.DEBUG))
                .addLast(new HttpServerCodec())
                .addLast(new HttpObjectAggregator(65536))
                .addLast(new WebSocketServerCompressionHandler())
                .addLast(new WebSocketServerProtocolHandler("/fbs", null, true))
                .addLast(new WebsocketDecoder())
                .addLast(new WebsocketHandler());
          }
        })
        .childHandler(
            new ChannelInitializer<>() {

              @Override
              protected void initChannel(Channel channel) {
                channel.pipeline()
                    .addLast(new LoggingHandler(LogLevel.INFO))
                    .addLast(new HttpServerCodec())
                    .addLast(new HttpObjectAggregator(65536))
                    .addLast(new WebSocketServerCompressionHandler())
                    .addLast(new WebSocketServerProtocolHandler("/json", null, true))
                    .addLast(new WebsocketHandler());
              }
            }
        );

    try {
      val channelFuture = serverBootstrap.bind(1202).sync();
      channelFuture.channel().closeFuture().sync();
    } catch (InterruptedException interruptedException) {
      log.error("Interrupted", interruptedException);
    } finally {
      parentGroup.shutdownGracefully();
      childGroup.shutdownGracefully();
    }
  }
}