org.powertac.samplebroker.core.MessageDispatcher.java Source code

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Here is the source code for org.powertac.samplebroker.core.MessageDispatcher.java

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/*
 * Copyright (c) 2012 by the original author
 *
 * 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.powertac.samplebroker.core;

import static org.powertac.util.MessageDispatcher.dispatch;

import java.lang.reflect.Field;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Set;

import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.Session;
import javax.jms.TextMessage;

import org.apache.log4j.Logger;
import org.powertac.common.IdGenerator;
import org.powertac.common.XMLMessageConverter;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.jms.core.JmsTemplate;
import org.springframework.jms.core.MessageCreator;
import org.springframework.stereotype.Service;

/**
 * Routes incoming messages to broker components, and outgoing messages
 * to the server. 
 * Components must register for specific message types with the broker, 
 * which passes the registrations to this router. For this to work, 
 * registered components must implement a handleMessage(msg) method that
 * takes the specified type as its single argument.
 * @author John Collins
 */
@Service
public class MessageDispatcher {
    static private Logger log = Logger.getLogger(MessageDispatcher.class);

    @Autowired
    private XMLMessageConverter converter;

    @Autowired
    private JmsTemplate template;

    @Autowired
    private JmsManagementService jmsManagementService;

    private HashMap<Class<?>, Set<Object>> registrations;
    String key = ""; // server registration secret

    /**
     * Default constructor
     */
    public MessageDispatcher() {
        super();
        registrations = new HashMap<Class<?>, Set<Object>>();
    }

    void setKey(String key) {
        this.key = key;
    }

    // ------------- incoming messages ----------------
    /**
     * Sets up handlers for incoming messages by message type.
     */
    public void registerMessageHandler(Object handler, Class<?> messageType) {
        Set<Object> reg = registrations.get(messageType);
        if (reg == null) {
            reg = new HashSet<Object>();
            registrations.put(messageType, reg);
        }
        reg.add(handler);
    }

    /**
     * Routes incoming messages from the server
     */
    public void routeMessage(Object message) {
        Class<?> clazz = message.getClass();
        log.debug("Route " + clazz.getName());
        Set<Object> targets = registrations.get(clazz);
        if (targets == null) {
            log.warn("no targets for message of type " + clazz.getName());
            return;
        }
        for (Object target : targets) {
            dispatch(target, "handleMessage", message);
        }
    }

    // ------------------ Outgoing messages ------------------
    /**
     * Sends outgoing messages to the server
     */
    public void sendMessage(Object message) {
        if (!validateId(message))
            return;
        final String text = key + converter.toXML(message);
        log.info("sending text: \n" + text);

        template.send(jmsManagementService.getServerQueueName(), new MessageCreator() {
            @Override
            public Message createMessage(Session session) throws JMSException {
                TextMessage message = session.createTextMessage(text);
                return message;
            }
        });
    }

    private boolean validateId(Object thing) {
        try {
            Field idField = thing.getClass().getDeclaredField("id");
            idField.setAccessible(true);
            long value = idField.getLong(thing);
            if (IdGenerator.getPrefix() != IdGenerator.extractPrefix(value)) {
                log.error("Invalid id value " + value + " in message " + thing.toString());
                return false;
            }
        } catch (NoSuchFieldException e) {
            // no id field, OK to send
            return true;
        } catch (SecurityException e) {
            // Should not happen
            log.error("Exception accessing id field: " + e.toString());
        } catch (IllegalArgumentException e) {
            // Should not happen
            log.error("Exception reading id field: " + e.toString());
        } catch (IllegalAccessException e) {
            // Should not happen
            log.error("Exception reading id field: " + e.toString());
        }
        return true;
    }

    // test-support
    Set<Object> getRegistrations(Class<?> messageType) {
        return registrations.get(messageType);
    }
}