code: /*
   * Copyright (c) 2019 the Eclipse Milo Authors
   *
   * This program and the accompanying materials are made
   * available under the terms of the Eclipse Public License 2.0
   * which is available at https://www.eclipse.org/legal/epl-2.0/
   *
   * SPDX-License-Identifier: EPL-2.0
   */
  
  package org.eclipse.milo.opcua.stack.client.transport.websocket;
  
  import java.net.URI;
  import java.util.concurrent.CompletableFuture;
  
  import io.netty.channel.ChannelInitializer;
  import io.netty.channel.socket.SocketChannel;
  import io.netty.handler.codec.http.DefaultHttpHeaders;
  import io.netty.handler.codec.http.HttpClientCodec;
  import io.netty.handler.codec.http.HttpObjectAggregator;
  import io.netty.handler.codec.http.websocketx.WebSocketClientHandshakerFactory;
  import io.netty.handler.codec.http.websocketx.WebSocketClientProtocolHandler;
  import io.netty.handler.codec.http.websocketx.WebSocketFrameAggregator;
  import io.netty.handler.codec.http.websocketx.WebSocketVersion;
  import io.netty.handler.logging.LogLevel;
  import io.netty.handler.logging.LoggingHandler;
  import io.netty.handler.ssl.SslContext;
  import io.netty.handler.ssl.SslContextBuilder;
  import io.netty.handler.ssl.util.InsecureTrustManagerFactory;
  import org.eclipse.milo.opcua.stack.client.UaStackClient;
  import org.eclipse.milo.opcua.stack.client.transport.uasc.ClientSecureChannel;
  import org.eclipse.milo.opcua.stack.core.StatusCodes;
  import org.eclipse.milo.opcua.stack.core.UaException;
  import org.eclipse.milo.opcua.stack.core.transport.TransportProfile;
  import org.eclipse.milo.opcua.stack.core.util.EndpointUtil;
  
  public class OpcClientWebSocketChannelInitializer extends ChannelInitializer<SocketChannel> {
  
      private final UaStackClient client;
      private final CompletableFuture<ClientSecureChannel> handshake;
  
      public OpcClientWebSocketChannelInitializer(
          UaStackClient client,
          CompletableFuture<ClientSecureChannel> handshake) {
  
          this.client = client;
          this.handshake = handshake;
      }
  
      @Override
      protected void initChannel(SocketChannel channel) throws Exception {
          String endpointUrl = client.getConfig().getEndpoint().getEndpointUrl();
          String scheme = EndpointUtil.getScheme(endpointUrl);
  
          TransportProfile transportProfile = TransportProfile
              .fromUri(client.getConfig().getEndpoint().getTransportProfileUri());
  
          String subprotocol;
          if (transportProfile == TransportProfile.WSS_UASC_UABINARY) {
              subprotocol = "opcua+cp";
          } else if (transportProfile == TransportProfile.WSS_UAJSON) {
              subprotocol = "opcua+uajson";
          } else {
              throw new UaException(
                  StatusCodes.Bad_InternalError,
                  "unexpected TransportProfile: " + transportProfile);
          }
  
          if ("opc.wss".equalsIgnoreCase(scheme)) {
              SslContext sslContext = SslContextBuilder.forClient()
                  .trustManager(InsecureTrustManagerFactory.INSTANCE)
                  .build();
  
              channel.pipeline().addLast(sslContext.newHandler(channel.alloc()));
          }
  
          int maxMessageSize = client.getConfig().getEncodingLimits().getMaxMessageSize();
  
          channel.pipeline().addLast(new LoggingHandler(LogLevel.INFO));
          channel.pipeline().addLast(new HttpClientCodec());
          channel.pipeline().addLast(new HttpObjectAggregator(maxMessageSize));
  
          channel.pipeline().addLast(
              new WebSocketClientProtocolHandler(
                  WebSocketClientHandshakerFactory.newHandshaker(
                      new URI(endpointUrl),
                      WebSocketVersion.V13,
                      subprotocol,
                      true,
                      new DefaultHttpHeaders(),
                      client.getConfig().getEncodingLimits().getMaxChunkSize()
                  )
              )
          );
  
          channel.pipeline().addLast(
              new WebSocketFrameAggregator(
                  client.getConfig().getEncodingLimits().getMaxMessageSize())
          );
  
          // OpcClientWebSocketFrameCodec adds UascClientAcknowledgeHandler when the WS upgrade is done.
          channel.pipeline().addLast(new OpcClientWebSocketBinaryFrameCodec(client, handshake));
      }
  
  }
  