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The Apache Log4j Implementation
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/*
 * 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.logging.log4j.core.net.server;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.nio.charset.Charset;
import java.util.concurrent.atomic.AtomicReference;
import javax.jms.JMSException;
import javax.jms.Message;
import javax.jms.MessageConsumer;
import javax.jms.MessageListener;
import javax.jms.ObjectMessage;

import org.apache.logging.log4j.LoggingException;
import org.apache.logging.log4j.core.LifeCycle;
import org.apache.logging.log4j.core.LogEvent;
import org.apache.logging.log4j.core.LogEventListener;
import org.apache.logging.log4j.core.appender.mom.JmsManager;
import org.apache.logging.log4j.core.net.JndiManager;

/**
 * LogEventListener server that receives LogEvents over a JMS {@link javax.jms.Destination}.
 *
 * @since 2.1
 */
public class JmsServer extends LogEventListener implements MessageListener, LifeCycle {

    private final AtomicReference state = new AtomicReference<>(State.INITIALIZED);
    private final JmsManager jmsManager;
    private MessageConsumer messageConsumer;

    public JmsServer(final String connectionFactoryBindingName,
                     final String destinationBindingName,
                     final String username,
                     final String password) {
        final String managerName = JmsServer.class.getName() + '@' + JmsServer.class.hashCode();
        final JndiManager jndiManager = JndiManager.getDefaultManager(managerName);
        jmsManager = JmsManager.getJmsManager(managerName, jndiManager, connectionFactoryBindingName,
            destinationBindingName, username, password);
    }

    @Override
    public State getState() {
        return state.get();
    }

    @Override
    public void onMessage(final Message message) {
        try {
            if (message instanceof ObjectMessage) {
                final Object body = ((ObjectMessage) message).getObject();
                if (body instanceof LogEvent) {
                    log((LogEvent) body);
                } else {
                    LOGGER.warn("Expected ObjectMessage to contain LogEvent. Got type {} instead.", body.getClass());
                }
            } else {
                LOGGER.warn("Received message of type {} and JMSType {} which cannot be handled.", message.getClass(),
                    message.getJMSType());
            }
        } catch (final JMSException e) {
            LOGGER.catching(e);
        }
    }

    @Override
    public void initialize() {
    }

    @Override
    public void start() {
        if (state.compareAndSet(State.INITIALIZED, State.STARTING)) {
            try {
                messageConsumer = jmsManager.createMessageConsumer();
                messageConsumer.setMessageListener(this);
            } catch (final JMSException e) {
                throw new LoggingException(e);
            }
        }
    }

    @Override
    public void stop() {
        try {
            messageConsumer.close();
        } catch (final JMSException ignored) {
        }
        jmsManager.release();
    }

    @Override
    public boolean isStarted() {
        return state.get() == State.STARTED;
    }

    @Override
    public boolean isStopped() {
        return state.get() == State.STOPPED;
    }

    /**
     * Starts and runs this server until the user types "exit" into standard input.
     *
     * @throws IOException
     * @since 2.6
     */
    public void run() throws IOException {
        this.start();
        System.out.println("Type \"exit\" to quit.");
        final BufferedReader stdin = new BufferedReader(new InputStreamReader(System.in, Charset.defaultCharset()));
        while (true) {
            final String line = stdin.readLine();
            if (line == null || line.equalsIgnoreCase("exit")) {
                System.out.println("Exiting. Kill the application if it does not exit due to daemon threads.");
                this.stop();
                return;
            }
        }
    }

}