XmlEtmConfigurator.java

/*
 *
 * Copyright (c) void.fm
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without modification,
 * are permitted provided that the following conditions are met:
 *
 * Redistributions of source code must retain the above copyright notice, this list
 * of conditions and the following disclaimer.
 *
 * Redistributions in binary form must reproduce the above copyright notice, this
 * list of conditions and the following disclaimer in the documentation and/or
 * other materials provided with the distribution.
 *
 * Neither the name void.fm nor the names of its contributors may be
 * used to endorse or promote products derived from this software without specific
 * prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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package etm.core.configuration;

import etm.core.monitor.EtmMonitor;

import java.io.ByteArrayInputStream;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.net.MalformedURLException;
import java.net.URL;

/**
 * A configurator that reads its configuration from xml. Currently supports both
 * jetm_config 1.0 and 1.2 configurations. See EtmManager howto that is part of
 * the documentation and  <a href="http://jetm.void.fm/dtd/">http://jetm.void.fm/dtd</a>
 * for currently supported dtds.
 *
 * <p/>
 * Every xml configuration file has to include one of the following doctype definitions
 * <pre>
 * <!DOCTYPE jetm-config PUBLIC "-// void.fm //DTD JETM Config 1.0//EN"
 *                           "http://jetm.void.fm/dtd/jetm_config_1_0.dtd">
 *
 * <!DOCTYPE jetm-config PUBLIC "-// void.fm //DTD JETM Config 1.2//EN"
 *                            http://jetm.void.fm/dtd/jetm_config_1_2.dtd">
 * </pre>
 * <p/>
 * Be aware that you need to start and stop the EtmMonitor before
 * using it. Example:
 * <pre>
 *  XmlEtmConfigurator.configure(new File("etm-config.xml"));
 *
 *  EtmMonitor etmMonitor = EtmManager.getEtmMonitor();
 *  etmMonitor.start();
 *  ...
 * </pre>
 *
 * @author void.fm
 * @version $Revision$
 */
public class XmlEtmConfigurator {

  private XmlEtmConfigurator() {
  }

  /**
   * Configures the EtmManager using the given string which represents
   * a valid XmlEtmConfigurator configuration.
   *
   * @param config The xml configuration string in UTF-8 format.
   * @throws EtmConfigurationException Thrown in case an error occures.
   */
  public static void configure(String config) {
    InputStream inStream = null;
    try {
      inStream = new ByteArrayInputStream(config.getBytes("UTF-8"));
      doConfigure(inStream);        
    } catch (EtmConfigurationException e) {
      throw e;
    } catch (Exception e) {
      throw new EtmConfigurationException(e);
    } finally {
      if (inStream != null) {
        try {
          inStream.close();
        } catch (IOException e) {
          // ignored
        }
      }
    }
  }

  /**
   * Configures the EtmManager using the given URL.
   *
   * @param configLocation The location of the file which may be remote or locally.
   * @throws EtmConfigurationException Thrown in case an error occures.
   */
  public static void configure(URL configLocation) {
    InputStream inStream = null;

    try {
      inStream = configLocation.openStream();
      doConfigure(inStream);
    } catch (EtmConfigurationException e) {
      throw e;
    } catch (Exception e) {
      throw new EtmConfigurationException(e);
    } finally {
      if (inStream != null) {
        try {
          inStream.close();
        } catch (IOException e) {
          // ignored
        }
      }
    }
  }

  /**
   * Configures the EtmManager using the given inputStream.
   * The stream will not be closed after usage.
   *
   * @param in The inputStream to be used.
   * @throws EtmConfigurationException Thrown in case an error occures.
   */
  public static void configure(InputStream in) {
    try {
      doConfigure(in);
    } catch (EtmConfigurationException e) {
      throw e;
    } catch (Exception e) {
      throw new EtmConfigurationException(e);
    }
  }

  /**
   * Configures the EtmManager using the given file. Delegates to
   * {@link #configure(java.net.URL)} only.
   *
   * @param file The config filefile to be used.
   * @throws EtmConfigurationException Thrown in case an error occures.
   */
  public static void configure(File file) {
    try {
      configure(file.toURL());
    } catch (MalformedURLException e) {
      throw new EtmConfigurationException(e);
    }
  }

  private static void doConfigure(InputStream in) throws Exception {
    EtmMonitorConfig monitorConfig = XmlConfigParser.extractConfig(in);

    EtmMonitor etmMonitor = EtmMonitorFactory.createEtmMonitor(monitorConfig);
    EtmManager.configure(etmMonitor);
  }

}