Java tutorial
/* * Copyright 2014 Matthias Einwag * * The jawampa authors license this file to you 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 ws.wamp.jawampa.transport; import java.util.List; import ws.wamp.jawampa.WampMessages.WampMessage; import com.fasterxml.jackson.databind.ObjectMapper; import com.fasterxml.jackson.databind.node.ArrayNode; import io.netty.buffer.ByteBufInputStream; import io.netty.buffer.Unpooled; import io.netty.channel.ChannelFutureListener; import io.netty.channel.ChannelHandlerContext; import io.netty.handler.codec.MessageToMessageDecoder; import io.netty.handler.codec.http.websocketx.BinaryWebSocketFrame; import io.netty.handler.codec.http.websocketx.CloseWebSocketFrame; 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.util.internal.logging.InternalLogger; import io.netty.util.internal.logging.InternalLoggerFactory; public class WampDeserializationHandler extends MessageToMessageDecoder<WebSocketFrame> { private static final InternalLogger logger = InternalLoggerFactory .getInstance(WampDeserializationHandler.class); enum ReadState { Closed, Reading, Error } ReadState readState = ReadState.Closed; final ObjectMapper objectMapper; final Serialization serialization; public Serialization serialization() { return serialization; } public WampDeserializationHandler(Serialization serialization, ObjectMapper objectMapper) { this.serialization = serialization; this.objectMapper = objectMapper; } @Override public void handlerAdded(ChannelHandlerContext ctx) { readState = ReadState.Reading; } @Override public void channelActive(ChannelHandlerContext ctx) { readState = ReadState.Reading; ctx.fireChannelActive(); } @Override public void channelInactive(ChannelHandlerContext ctx) { readState = ReadState.Closed; ctx.fireChannelInactive(); } @Override protected void decode(ChannelHandlerContext ctx, WebSocketFrame frame, List<Object> out) throws Exception { if (readState != ReadState.Reading) return; if (frame instanceof TextWebSocketFrame) { // Only want Text when JSON subprotocol if (serialization != Serialization.Json) throw new IllegalStateException("Received unexpected TextFrame"); TextWebSocketFrame textFrame = (TextWebSocketFrame) frame; if (logger.isDebugEnabled()) { logger.debug("Deserialized Wamp Message: {}", textFrame.text()); } //System.out.println("Deserialized Wamp message: " + textFrame.text()); try { // If we receive an invalid frame on of the following functions will throw // This will lead Netty to closing the connection ArrayNode arr = objectMapper.readValue(new ByteBufInputStream(textFrame.content()), ArrayNode.class); WampMessage recvdMessage = WampMessage.fromObjectArray(arr); out.add(recvdMessage); } finally { } } else if (frame instanceof BinaryWebSocketFrame) { // Only want Binary when MessagePack subprotocol if (serialization != Serialization.MessagePack) throw new IllegalStateException("Received unexpected BinaryFrame"); // TODO: Support MessagePack } else if (frame instanceof PongWebSocketFrame) { // System.out.println("WebSocket Client received pong"); } else if (frame instanceof CloseWebSocketFrame) { // System.out.println("WebSocket Client received closing"); readState = ReadState.Closed; } } @Override public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) { // We caught an exception. // Most probably because we received an invalid message readState = ReadState.Error; ctx.writeAndFlush(Unpooled.EMPTY_BUFFER).addListener(ChannelFutureListener.CLOSE); } }