Java tutorial
/* * Copyright (c) 2017, WSO2 Inc. (http://wso2.com) All Rights Reserved. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package org.ballerinalang.composer.service.workspace.launcher; import io.netty.buffer.ByteBuf; import io.netty.buffer.Unpooled; import io.netty.channel.ChannelFuture; import io.netty.channel.ChannelFutureListener; import io.netty.channel.ChannelHandlerContext; import io.netty.channel.SimpleChannelInboundHandler; import io.netty.handler.codec.http.DefaultFullHttpResponse; import io.netty.handler.codec.http.FullHttpRequest; import io.netty.handler.codec.http.FullHttpResponse; import io.netty.handler.codec.http.HttpHeaders; import io.netty.handler.codec.http.websocketx.CloseWebSocketFrame; import io.netty.handler.codec.http.websocketx.PingWebSocketFrame; import io.netty.handler.codec.http.websocketx.PongWebSocketFrame; import io.netty.handler.codec.http.websocketx.TextWebSocketFrame; import io.netty.handler.codec.http.websocketx.WebSocketFrame; import io.netty.handler.codec.http.websocketx.WebSocketServerHandshaker; import io.netty.handler.codec.http.websocketx.WebSocketServerHandshakerFactory; import io.netty.util.CharsetUtil; import static io.netty.handler.codec.http.HttpHeaders.Names.HOST; import static io.netty.handler.codec.http.HttpMethod.GET; import static io.netty.handler.codec.http.HttpResponseStatus.*; import static io.netty.handler.codec.http.HttpResponseStatus.OK; import static io.netty.handler.codec.http.HttpVersion.HTTP_1_1; /** * Handler of launch websocket server. */ public class LaunchServerHandler extends SimpleChannelInboundHandler<Object> { private WebSocketServerHandshaker handshaker; @Override public void channelRead0(ChannelHandlerContext ctx, Object msg) { if (msg instanceof FullHttpRequest) { handleHttpRequest(ctx, (FullHttpRequest) msg); } else if (msg instanceof WebSocketFrame) { handleWebSocketFrame(ctx, (WebSocketFrame) msg); } } @Override public void channelReadComplete(ChannelHandlerContext ctx) { ctx.flush(); } private void handleHttpRequest(ChannelHandlerContext ctx, FullHttpRequest req) { // Handle a bad request. if (!req.getDecoderResult().isSuccess()) { sendHttpResponse(ctx, req, new DefaultFullHttpResponse(HTTP_1_1, BAD_REQUEST)); return; } // Allow only GET methods. if (req.getMethod() != GET) { sendHttpResponse(ctx, req, new DefaultFullHttpResponse(HTTP_1_1, FORBIDDEN)); return; } if (!LauncherConstants.LAUNCHER_WEBSOCKET_PATH.equals(req.getUri())) { FullHttpResponse res = new DefaultFullHttpResponse(HTTP_1_1, NOT_FOUND); sendHttpResponse(ctx, req, res); return; } // Handshake WebSocketServerHandshakerFactory wsFactory = new WebSocketServerHandshakerFactory(getWebSocketLocation(req), null, true); handshaker = wsFactory.newHandshaker(req); if (handshaker == null) { WebSocketServerHandshakerFactory.sendUnsupportedVersionResponse(ctx.channel()); } else { LaunchManager launchManager = LaunchManager.getInstance(); launchManager.addLaunchSession(ctx.channel()); handshaker.handshake(ctx.channel(), req); } } private void handleWebSocketFrame(ChannelHandlerContext ctx, WebSocketFrame frame) { // Check for closing frame if (frame instanceof CloseWebSocketFrame) { handshaker.close(ctx.channel(), (CloseWebSocketFrame) frame.retain()); return; } if (frame instanceof PingWebSocketFrame) { ctx.channel().write(new PongWebSocketFrame(frame.content().retain())); return; } if (!(frame instanceof TextWebSocketFrame)) { throw new UnsupportedOperationException( String.format("%s frame types not supported", frame.getClass().getName())); } String request = ((TextWebSocketFrame) frame).text(); LaunchManager launchManager = LaunchManager.getInstance(); launchManager.processCommand(request); } private static void sendHttpResponse(ChannelHandlerContext ctx, FullHttpRequest req, FullHttpResponse res) { // Generate an error page if response getStatus code is not OK (200). if (res.getStatus().code() != OK.code()) { ByteBuf buf = Unpooled.copiedBuffer(res.getStatus().toString(), CharsetUtil.UTF_8); res.content().writeBytes(buf); buf.release(); HttpHeaders.setContentLength(res, res.content().readableBytes()); } // Send the response and close the connection if necessary. ChannelFuture f = ctx.channel().writeAndFlush(res); if (!HttpHeaders.isKeepAlive(req) || res.getStatus().code() != OK.code()) { f.addListener(ChannelFutureListener.CLOSE); } } @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) { //@todo proper error handling ctx.close(); } private static String getWebSocketLocation(FullHttpRequest req) { String location = req.headers().get(HOST) + LauncherConstants.LAUNCHER_WEBSOCKET_PATH; return "ws://" + location; } }