Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses 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 org.apache.thrift; import org.apache.thrift.protocol.*; import java.util.Map; import java.util.HashMap; /** * <code>TMultiplexedProcessor</code> is a <code>TProcessor</code> allowing * a single <code>TServer</code> to provide multiple services. * * <p>To do so, you instantiate the processor and then register additional * processors with it, as shown in the following example:</p> * * <blockquote><code> * TMultiplexedProcessor processor = new TMultiplexedProcessor(); * * processor.registerProcessor( * "Calculator", * new Calculator.Processor(new CalculatorHandler())); * * processor.registerProcessor( * "WeatherReport", * new WeatherReport.Processor(new WeatherReportHandler())); * * TServerTransport t = new TServerSocket(9090); * TSimpleServer server = new TSimpleServer(processor, t); * * server.serve(); * </code></blockquote> */ public class TMultiplexedProcessor implements TProcessor { private final Map<String, TProcessor> SERVICE_PROCESSOR_MAP = new HashMap<String, TProcessor>(); private TProcessor defaultProcessor; /** * 'Register' a service with this <code>TMultiplexedProcessor</code>. This * allows us to broker requests to individual services by using the service * name to select them at request time. * * @param serviceName Name of a service, has to be identical to the name * declared in the Thrift IDL, e.g. "WeatherReport". * @param processor Implementation of a service, usually referred to * as "handlers", e.g. WeatherReportHandler implementing WeatherReport.Iface. */ public void registerProcessor(String serviceName, TProcessor processor) { SERVICE_PROCESSOR_MAP.put(serviceName, processor); } /** * Register a service to be called to process queries without service name * @param processor */ public void registerDefault(TProcessor processor) { defaultProcessor = processor; } /** * This implementation of <code>process</code> performs the following steps: * * <ol> * <li>Read the beginning of the message.</li> * <li>Extract the service name from the message.</li> * <li>Using the service name to locate the appropriate processor.</li> * <li>Dispatch to the processor, with a decorated instance of TProtocol * that allows readMessageBegin() to return the original TMessage.</li> * </ol> * * @throws TProtocolException If the message type is not CALL or ONEWAY, if * the service name was not found in the message, or if the service * name was not found in the service map. You called {@link #registerProcessor(String, TProcessor) registerProcessor} * during initialization, right? :) */ public void process(TProtocol iprot, TProtocol oprot) throws TException { /* Use the actual underlying protocol (e.g. TBinaryProtocol) to read the message header. This pulls the message "off the wire", which we'll deal with at the end of this method. */ TMessage message = iprot.readMessageBegin(); if (message.type != TMessageType.CALL && message.type != TMessageType.ONEWAY) { throw new TProtocolException(TProtocolException.NOT_IMPLEMENTED, "This should not have happened!?"); } // Extract the service name int index = message.name.indexOf(TMultiplexedProtocol.SEPARATOR); if (index < 0) { if (defaultProcessor != null) { // Dispatch processing to the stored processor defaultProcessor.process(new StoredMessageProtocol(iprot, message), oprot); return; } throw new TProtocolException(TProtocolException.NOT_IMPLEMENTED, "Service name not found in message name: " + message.name + ". Did you " + "forget to use a TMultiplexProtocol in your client?"); } // Create a new TMessage, something that can be consumed by any TProtocol String serviceName = message.name.substring(0, index); TProcessor actualProcessor = SERVICE_PROCESSOR_MAP.get(serviceName); if (actualProcessor == null) { throw new TProtocolException(TProtocolException.NOT_IMPLEMENTED, "Service name not found: " + serviceName + ". Did you forget " + "to call registerProcessor()?"); } // Create a new TMessage, removing the service name TMessage standardMessage = new TMessage( message.name.substring(serviceName.length() + TMultiplexedProtocol.SEPARATOR.length()), message.type, message.seqid); // Dispatch processing to the stored processor actualProcessor.process(new StoredMessageProtocol(iprot, standardMessage), oprot); } /** * Our goal was to work with any protocol. In order to do that, we needed * to allow them to call readMessageBegin() and get a TMessage in exactly * the standard format, without the service name prepended to TMessage.name. */ private static class StoredMessageProtocol extends TProtocolDecorator { TMessage messageBegin; public StoredMessageProtocol(TProtocol protocol, TMessage messageBegin) { super(protocol); this.messageBegin = messageBegin; } @Override public TMessage readMessageBegin() throws TException { return messageBegin; } } }