/*
    * 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.oodt.commons;
  
  import java.io.*;
  import java.net.MalformedURLException;
  import java.net.URL;
  import java.net.UnknownHostException;
  import java.util.*;
  import org.apache.oodt.commons.util.*;
  import org.w3c.dom.*;
  import org.xml.sax.*;
  import javax.naming.Context;
  import javax.naming.InitialContext;
  import javax.naming.NamingException;
  import javax.naming.NoInitialContextException;
  import java.rmi.registry.Registry;
  import java.util.StringTokenizer;
  
  /** EDA Configuration.
   *
   * An object of this class represents the configuration information for the EDA software.
   *
   * @author Kelly
   */
  public class Configuration {
  	/** The singleton configuration. */
  	static Configuration configuration = null;
  
  	/** Name of property that specifies the direcotries that contains XML entities. */
  	public static final String ENTITY_DIRS_PROP = "entity.dirs";
  
  	/** Name of the default config file. */
  	public static final String DEFAULT_CONFIG_FILE = ".edarc.xml";
  
  	/** Alternate config file. */
  	public static final String ALT_CONFIG_FILE = ".oodtrc.xml";
  
  	/** Library-location config file. */
  	public static final File LIB_CONFIG_FILE = new File(System.getProperty("java.home", "/") + File.separator + "lib"
  		+ File.separator + "edarc.xml");
  
  	/** Non-JRE library location of config file. */
  	public static final File ALT_LIB_CONFIG_FILE = new File(System.getProperty("java.home", "/") + File.separator + ".."
  		+ File.separator + "lib" + File.separator + "edarc.xml");
  
  	 /** Get the singleton configuration.
  	  *
  	  * This method returns the singleton configuration object, or creates it if it
  	  * doesn't yet exist.  To create it, it reads the configuration file specified by
  	  * the system property <code>org.apache.oodt.commons.Configuration.url</code> or the file in the
  	  * user's home directory called .edarc.xml if the system property isn't
  	  * specified.  It parses the file and returns a <code>Configuration</code> object
  	  * initialized with the data specified therein.
  	  *
  	  * @throws IOException If reading the configuration file fails.
  	  * @throws SAXException If parsing the configuration file fails.
  	  * @throws MalformedURLException If the URL specification is invalid.
  	  * @return An initialized configuration object.
  	  */
  	 public static Configuration getConfiguration() throws IOException, SAXException, MalformedURLException {
  		 // Got one?  Use it.
  		 if (configuration != null) return configuration;
  
  		 URL url;
  
  		 // First preference: URL via the org.apache.oodt.commons.Configuration.url prop.
  		 String urlString = System.getProperty("org.apache.oodt.commons.Configuration.url");
  		 if (urlString != null) {
  			 url = new URL(urlString);
  		 } else {
  			 File file = null;
  
  			 // Second preference: file via the org.apache.oodt.commons.Configuration.file prop.
  			 String filename = System.getProperty("org.apache.oodt.commons.Configuration.file");
  			 if (filename != null) {
  				 file = new File(filename);
  				 if (!file.exists()) throw new IOException("File " + file + " not found");
  			 } else {
  				 List candidates = new ArrayList();
  
  				 // Third preference: ~/.edarc.xml
  				 File homedir = new File(System.getProperty("user.home", "/"));
  				 File homedirfile = new File(homedir, DEFAULT_CONFIG_FILE);
 				 candidates.add(homedirfile);
 
 				 // Fourth preference: ~/.oodtrc.xml
 				 File alt = new File(homedir, ALT_CONFIG_FILE);
 				 candidates.add(alt);
 
 				 // Fifth and sixth preferences: $EDA_HOME/conf/edarc.xml and $EDA_HOME/etc/edarc.xml
 				 String edaHome = System.getProperty("eda.home");
 				 if (edaHome != null) {
 					 File edaHomeDir = new File(edaHome);
 					 candidates.add(new File(new File(edaHomeDir, "conf"), "edarc.xml"));
 					 candidates.add(new File(new File(edaHomeDir, "etc"), "edarc.xml"));
 				 }
 
 				 // Seventh preference: JAVA_HOME/lib/edarc.xml
 				 candidates.add(LIB_CONFIG_FILE);
 
 				 // Final preference: JAVA_HOME/../lib/edarc.xml (to get out of JRE)
 				 candidates.add(ALT_LIB_CONFIG_FILE);
 
 				 // Now find one.
 				 boolean found = false;
 				 for (Iterator i = candidates.iterator(); i.hasNext();) {
 					 file = (File) i.next();
 					 if (file.exists()) {
 						 found = true;
 						 break;
 					 }
 				 }
 				 if (found && file == alt)
 					 System.err.println("WARNING: Using older config file " + alt + "; rename to "
 						 + homedirfile + " as soon as possible.");
 				 if (!found) {
 					 return getEmptyConfiguration();
 				 }
 			 }
 			 url = file.toURL();
 		 }
 
 		 return getConfiguration(url);
 
 	 }
 
 	/** Get the singleton configuration.
 	 *
 	 * This method returns the singleton configuration object from a 
 	 * specified file url.  It parses the file and returns a <code>Configuration</code> object
 	 * initialized with the data specified therein.  Added by Chris Mattmann 12/05/03.
 	 *
 	 * @throws IOException If an I/O error occurs.
 	 * @return An initialized configuration object.
 	 */
 	public static Configuration getConfiguration(URL configFileUrl) throws SAXException, IOException {
 		synchronized (Configuration.class) {
 			if (configuration == null)
 				configuration = new Configuration(configFileUrl);
 		}
 		return configuration;
 	}
 
 	private static Configuration getEmptyConfiguration() {
 		synchronized (Configuration.class) {
 			if (configuration == null)
 				configuration = new Configuration();
 		}
 		return configuration;
 	}
 
 
 	/** Get the singleton configuration without exception.
 	 *
 	 * This method is identical to {@link #getConfiguration} but traps all checked
 	 * exceptions.  If the configuration can't be read, it returns null.
 	 *
 	 * @return An initialized configuration object, or null if an error occurred.
 	 */
 	public static Configuration getConfigurationWithoutException() {
 		// Got one?  Use it.  Do this out of a try block for performance.
 		if (configuration != null) return configuration;
 
 		// Try to get it.
 		try {
 			return getConfiguration();
 		} catch (RuntimeException ex) {
 			throw ex;
 		} catch (Exception ex) {
 			System.err.println("Exception " + ex.getClass().getName() + " while getting configuration: "
 				+ ex.getMessage());
 			ex.printStackTrace();
 			return null;
 		}
 	}
 
 	Configuration() {
 		serverMgrPort = 7577;
 		nameServerStateFrequency = 6000000;
 		nameServerObjectKey = "StandardNS%20POA";
 		nameServerPort = "10000";
 		nameServerHost = "localhost";
 		nameServerVersion = "1.0";
 		nameServerUsingRIRProtocol = false;
 		webServerDocumentDirectory = new File(System.getProperty("user.home", "/") + "tomcat/webapps/ROOT");
 		webPort = "8080";
 		webHost = "localhost";
 		System.setProperty(WEB_PROTOCOL_PROPERTY, "http");
 		initializeContext();
 	}
 
 	/** Construct a configuration.
 	 *
 	 * @param url The location of the configuration.
 	 * @throws IOException If reading the configuration file fails.
 	 * @throws SAXParseException If parsing the configuration file fails.
 	 */
 	Configuration(URL url) throws IOException, SAXException {
 		this(new InputSource(url.toString()));
 	}
 
 	Configuration(InputSource inputSource) throws IOException, SAXException {
 		String systemID = inputSource.getSystemId();
 		if (systemID == null) inputSource.setSystemId("file:/unknown");
 
 		// Get the document
 		DOMParser parser = XML.createDOMParser();
 		parser.setEntityResolver(new ConfigurationEntityResolver());
 		parser.setErrorHandler(new ErrorHandler() {
 			public void error(SAXParseException ex) throws SAXException {
 				throw ex;
 			}
 			public void warning(SAXParseException ex) {
 				System.err.println("Warning: " + ex.getMessage());
 			}
 			public void fatalError(SAXParseException ex) throws SAXException {
 				System.err.println("Fatal parse error: " + ex.getMessage());
 				throw ex;
 			}
 		});
 		parser.parse(inputSource);
 		Document document = parser.getDocument();
 		XML.removeComments(document);
 		document.normalize();
 		
 		// See if this really is a <configuration> document.
 		if (!document.getDocumentElement().getNodeName().equals("configuration"))
 			throw new SAXException("Configuration " + inputSource.getSystemId() + " is not a <configuration> document");
 
 		NodeList list = document.getDocumentElement().getChildNodes();
 		for (int eachChild = 0; eachChild < list.getLength(); ++eachChild) {
 			Node childNode = list.item(eachChild);
 			if (childNode.getNodeName().equals("webServer")) {
 				NodeList children = childNode.getChildNodes();
 				for (int i = 0; i < children.getLength(); ++i) {
 					Node node = children.item(i);
 					if ("host".equals(node.getNodeName()))
 						webHost = XML.unwrappedText(node);
 					else if ("port".equals(node.getNodeName()))
 						webPort = XML.unwrappedText(node);
 					else if ("dir".equals(node.getNodeName()))
 						webServerDocumentDirectory = new File(XML.unwrappedText(node));
 				}					
 				properties.setProperty("org.apache.oodt.commons.Configuration.webServer.baseURL", getWebServerBaseURL());
 				if (webServerDocumentDirectory == null)
 					webServerDocumentDirectory = new File(System.getProperty("user.home", "/")
 						+ "/dev/htdocs");
 			} else if (childNode.getNodeName().equals("nameServer")) {
 				Element nameServerNode = (Element) childNode;
 				String nameServerStateFrequencyString = nameServerNode.getAttribute("stateFrequency");
 				if (nameServerStateFrequencyString == null || nameServerStateFrequencyString.length() == 0)
 					nameServerStateFrequency = 0;
 				else try {
 					nameServerStateFrequency = Integer.parseInt(nameServerStateFrequencyString);
 				} catch (NumberFormatException ex) {
 					throw new SAXException("Illegal nun-numeric value \"" + nameServerStateFrequencyString
 						+ "\" for stateFrequency attribute");
 				}
 				if (childNode.getFirstChild().getNodeName().equals("rir")) {
 					nameServerUsingRIRProtocol = true;
 					NodeList children = childNode.getFirstChild().getChildNodes();
 					nameServerObjectKey = children.getLength() == 1? XML.unwrappedText(children.item(0)):null;
 				} else {
 					nameServerUsingRIRProtocol = false;
 					nameServerVersion = null;
 					nameServerPort = null;
 					// Must be same as CORBAMgr.NS_OBJECT_KEY:
 					nameServerObjectKey = "StandardNS/NameServer%2DPOA/_root";
 					NodeList children = childNode.getFirstChild().getChildNodes();
 					for (int i = 0; i < children.getLength(); ++i) {
 						Node node = children.item(i);
 						if (node.getNodeName().equals("version"))
 							nameServerVersion = XML.unwrappedText(node);
 						else if (node.getNodeName().equals("host"))
 							nameServerHost = XML.unwrappedText(node);
 						else if (node.getNodeName().equals("port"))
 							nameServerPort = XML.unwrappedText(node);
 						else if (node.getNodeName().equals("objectKey"))
 							nameServerObjectKey = XML.unwrappedText(node);
 					}
 				}
 			} else if (childNode.getNodeName().equals("xml")) {
 				NodeList children = childNode.getChildNodes();
 				for (int i = 0; i < children.getLength(); ++i) {
 					Node xmlNode = children.item(i);
 					if ("entityRef".equals(xmlNode.getNodeName())) {
 						NodeList dirNodes = xmlNode.getChildNodes();
 						StringBuffer refDirs = new StringBuffer(System.getProperty(ENTITY_DIRS_PROP, ""));
 						for (int j = 0; j < dirNodes.getLength(); ++j)
 							refDirs.append(',').append(XML.unwrappedText(dirNodes.item(j)));
 						if (refDirs.length() > 0)
 							System.setProperty(ENTITY_DIRS_PROP, refDirs.charAt(0) == ','?
 								refDirs.substring(1) : refDirs.toString());
 					}
 				}
 			} else if ("serverMgr".equals(childNode.getNodeName())) {
 				serverMgrPort = Integer.parseInt(XML.unwrappedText(childNode.getFirstChild()));
 			} else if (childNode.getNodeName().equals("properties")) {
 				loadProperties(childNode, properties);
 			} else if (childNode.getNodeName().equals("programs")) {
 				NodeList children = childNode.getChildNodes();
 				for (int i = 0; i < children.getLength(); ++i) {
 					// They're all of type execServer---for now.
 					ExecServerConfig esc = new ExecServerConfig(children.item(i));
 					esc.getProperties().setProperty("org.apache.oodt.commons.Configuration.url", inputSource.getSystemId());
 					execServers.add(esc);
 				}
 			}
 		}
 
 		initializeContext();
 	}
 
 	private void initializeContext() {
 		contextEnvironment.put(Context.INITIAL_CONTEXT_FACTORY, "org.apache.oodt.commons.object.jndi.ObjectCtxFactory");
 		String registryList = System.getProperty("org.apache.oodt.commons.rmiregistries", System.getProperty("rmiregistries"));
 		if (registryList == null) {
 			String host = System.getProperty("rmiregistry.host", "localhost");
 			int port = Integer.getInteger("rmiregistry.port", Registry.REGISTRY_PORT).intValue();
 			registryList = "rmi://" + host + ":" + port;
 		}
 		contextEnvironment.put("rmiregistries", registryList);
 	}
 
 	/** Serialize this configuration into a serialized XML document.
 	 *
 	 * @return Serialized XML version of this configuration.
 	 * @throws DOMException If an error occurs constructing the XML structure.
 	 */
 	public String toXML() throws DOMException {
 		Document doc = createDocument("configuration");
 		doc.replaceChild(toXML(doc), doc.getDocumentElement());
 		return XML.serialize(doc);
 	}
 
 	/** 
 	 *
 	 * @param document The document to which the XML structure will belong.
 	 * @return The root node representing this configuration.
 	 * @throws DOMException If an error occurs constructing the XML structure.
 	 */
 	public Node toXML(Document document) throws DOMException {
 		// <configuration>
 		Element configurationNode = document.createElement("configuration");
 
 		// <webServer>
 		Element webServerNode = document.createElement("webServer");
 		configurationNode.appendChild(webServerNode);
 
 		// <webServer>
 		//   <host>...</host><port>...</port><dir>...</dir>
 		XML.add(webServerNode, "host", webHost);
 		XML.add(webServerNode, "port", webPort);
 		XML.add(webServerNode, "dir", webServerDocumentDirectory.toString());
 
 		// <nameServer>
 		Element nameServerNode = document.createElement("nameServer");
 		nameServerNode.setAttribute("stateFrequency", String.valueOf(nameServerStateFrequency));
 		configurationNode.appendChild(nameServerNode);
 
 		// <nameServer>
 		//   <rir> or <iiop>
 		if (nameServerUsingRIRProtocol) {
 			Element rirNode = document.createElement("rir");
 			nameServerNode.appendChild(rirNode);
 			if (nameServerObjectKey != null)
 				XML.add(rirNode, "objectKey", nameServerObjectKey);
 		} else {
 			Element iiopNode = document.createElement("iiop");
 			nameServerNode.appendChild(iiopNode);
 			if (nameServerVersion != null)
 				XML.add(iiopNode, "version", nameServerVersion);
 			XML.add(iiopNode, "host", nameServerHost);
 			if (nameServerPort != null)
 				XML.add(iiopNode, "port", nameServerPort);
 			if (nameServerObjectKey != null)
 				XML.add(iiopNode, "objectKey", nameServerObjectKey);
 		}
 
 		// <xml><entityRef><dir>...
 		if (!getEntityRefDirs().isEmpty()) {
 			Element xmlNode = document.createElement("xml");
 			configurationNode.appendChild(xmlNode);
 			Element entityRefNode = document.createElement("entityRef");
 			xmlNode.appendChild(entityRefNode);
 			XML.add(entityRefNode, "dir", getEntityRefDirs());
 		}
 
 		// <serverMgr><port>...
 		if (getServerMgrPort() != 0) {
 			Element serverMgrNode = document.createElement("serverMgr");
 			configurationNode.appendChild(serverMgrNode);
 			XML.add(serverMgrNode, "port", String.valueOf(getServerMgrPort()));
 		}
 
 		// Global <properties>...</properties>
 		if (properties.size() > 0)
 			dumpProperties(properties, configurationNode);
 
 		// <programs>...
 		if (execServers.size() > 0) {
 			Element programsNode = document.createElement("programs");
 			configurationNode.appendChild(programsNode);
 
 			for (Iterator i = execServers.iterator(); i.hasNext();) {
 				ExecServerConfig esc = (ExecServerConfig) i.next();
 				Element execServerNode = document.createElement("execServer");
 				programsNode.appendChild(execServerNode);
 				XML.add(execServerNode, "class", esc.getClassName());
 				XML.add(execServerNode, "objectKey", esc.getObjectKey());
 				XML.add(execServerNode, "host", esc.getPreferredHost().toString());
 				if (esc.getProperties().size() > 0)
 					dumpProperties(esc.getProperties(), execServerNode);
 			}
 		}
 
 		return configurationNode;
 	}
 
 	/** Merge the properties in the configuration into the given properties.
 	 *
 	 * Properties that already exist in the <var>targetProps</var> won't be
 	 * overwritten.
 	 *
 	 * @param targetProps The target properties.
 	 */
 	public void mergeProperties(Properties targetProps) {
 		for (Iterator i = properties.entrySet().iterator(); i.hasNext();) {
 			Map.Entry entry = (Map.Entry) i.next();
 			if (!targetProps.containsKey(entry.getKey()))
 				targetProps.put(entry.getKey(), entry.getValue());
 		}
 	}
 
 	/** Get the exec-server configurations.
 	 *
 	 * @return A collection of exec server configurations, each of class {@link ExecServerConfig}.
 	 */
 	public Collection getExecServerConfigs() {
 		return execServers;
 	}
 
         /** Get the exec-server configurations.
          *
          * @param clazz The class of exec servers that will be returned.
          * @return A collection of exec server configurations, each of class {@link ExecServerConfig}.
          */
         public Collection getExecServerConfigs(Class clazz) {
                 String className = clazz.getName();
                 Collection execServerConfigs = new ArrayList();
                 for (Iterator i = execServers.iterator(); i.hasNext();) {
                         ExecServerConfig exec = (ExecServerConfig) i.next();
                         if (className.equals(exec.getClassName()))
                                 execServerConfigs.add(exec);
                 }
                 return execServerConfigs;
         }
 
         /** Get an exec-server configuration.
          *
          * @param objectKey The object key of the Exec Server to retrieve.
          * @return An {@link ExecServerConfig} or null if object key not found.
          */
         public ExecServerConfig getExecServerConfig(String objectKey) {
                 ExecServerConfig execServerConfig = null;
                 for (Iterator i = execServers.iterator(); i.hasNext() && execServerConfig == null;) {
                         ExecServerConfig exec = (ExecServerConfig) i.next();
                         if (objectKey.equals(exec.getObjectKey()))
                                 execServerConfig = exec;
                 }
                 return execServerConfig;
         }
 
 	/** Get the web server base URL.
 	 *
 	 * @return The base web server URL.
 	 */
 	public String getWebServerBaseURL() {
 		String proto = System.getProperty(WEB_PROTOCOL_PROPERTY);
 		if (proto == null) {
 			if ("443".equals(webPort)) proto = "https";
 			else proto = "http";
 		}
 		return proto + "://" + webHost + ":" + webPort;
 	}
 
 	/** Get the web server document directory.
 	 *
 	 * @return The document directory.
 	 */
 	public File getWebServerDocumentDirectory() {
 		return webServerDocumentDirectory;
 	}
 
 	/** Get the name server URL.
 	 *
 	 * @return The name server URL.
 	 */
 	public String getNameServerURL() {
 		return getWebServerBaseURL() + "/ns.ior";
 	}
 
 	/** Get the name server port, if any.
 	 *
 	 * @return The port.
 	 */
 	public String getNameServerPort() {
 		return nameServerPort;
 	}
 
 	/** Get the frequency with which the name server saves its state.
 	 *
 	 * @return The state-save frequency in milliseconds; <= 0 means never save state.
 	 */
 	public int getNameServerStateFrequency() {
 		return nameServerStateFrequency;
 	}
 
 	/** Get the object context.
 	 *
 	 * @return The object context based on this configuration.
 	 * @throws NamingException If the context can't be created.
 	 */
 	public Context getObjectContext() throws NamingException {
 		Context c = null;
 		final String className = (String) contextEnvironment.get(javax.naming.Context.INITIAL_CONTEXT_FACTORY);
 		if (className == null)
 			c = new InitialContext(contextEnvironment);
 		else try {
 			// Work around iPlanet bug.  JNDI uses the thread's context class
 			// loader to load the initial context factory class.  For some
 			// reason, that loader fails to find things in iPlanet's
 			// classpath, such as the EDA initial context factory.  Here, we
 			// cut a new thread and explicitly set its context class loader to
 			// the application class loader.  When JNDI looks up the initial
 			// context factory, the thread's context class loader is the app
 			// class loader, which succeeds.
 			Class clazz = Class.forName(className);
 			final ClassLoader loader = clazz.getClassLoader();
 			InitialContextThread thread = new InitialContextThread(loader);
 			thread.start();
 			try {
 				thread.join();
 			} catch (InterruptedException ex) {
 				throw new NoInitialContextException("Initial context thread interrupted: " + ex.getMessage());
 			}
 			c = thread.getContext();
 			if (c == null)
 				throw thread.getException();
 		} catch (ClassNotFoundException ex) {
 			throw new NoInitialContextException("Class " + className + " not found");
 		}
 		return c;
 	}
 
 	/** Get the entity reference directories.
 	 *
 	 * @return A list of {@link java.lang.String}s naming directories for entity references.
 	 */
 	public List getEntityRefDirs() {
 		List dirs = new ArrayList();
 		for (StringTokenizer t = new StringTokenizer(System.getProperty(ENTITY_DIRS_PROP, ""), ",;|"); t.hasMoreTokens();)
 			dirs.add(t.nextToken());
 		return dirs;
 	}
 
 	/** Get the port number on which the server manager is listening.
 	 *
 	 * @return The port number, or 0 if there is no server manager.
 	 */
 	public int getServerMgrPort() {
 		return serverMgrPort;
 	}
 
 	/** Load the properties described in an XML properties element into the
 	 * given properties object.
 	 *
 	 * @param propertiesNode The XML node which is a <code>&lt;properties&gt;</code> element.
 	 * @param props The properties object to load with properties from <var>propertiesNode</var>.
 	 */
 	static void loadProperties(Node propertiesNode, Properties props) {
 		NodeList children = propertiesNode.getChildNodes();
 		for (int i = 0; i < children.getLength(); i += 2) {
 			String key = XML.unwrappedText(children.item(i));
 			String value = XML.unwrappedText(children.item(i+1));
 			props.setProperty(key, value);
 		}
 	}
 
 	/** Dump the properties from the given properties object in XML form, appending
 	 * them to the given node under a &lt;properties&gt; element.
 	 *
 	 * @param props The properties to dump in XML form.
 	 * @param node The node to which to append the &lt;properties&gt; element.
 	 * @throws DOMException If a DOM error occurs.
 	 */
 	static void dumpProperties(Properties props, Node node) {
 		Element propertiesElement = node.getOwnerDocument().createElement("properties");
 		node.appendChild(propertiesElement);
 		for (Iterator i = props.entrySet().iterator(); i.hasNext();) {
 			Map.Entry entry = (Map.Entry) i.next();
 			XML.add(propertiesElement, "key", (String) entry.getKey());
 			XML.add(propertiesElement, "value", (String) entry.getValue());
 		}
 	}
 
 	/** Create a new XML document with the configuration DTD.
 	 *
 	 * @param name Name to give to the document element.
 	 * @returns An XML DOM document with the doctype and the root document empty element in place.
 	 * @throws DOMException If we can't create the document.
 	 */
 	static Document createDocument(String documentElementName) throws DOMException {
 		DocumentType docType = XML.getDOMImplementation().createDocumentType(documentElementName, DTD_FPI, DTD_URL);
 		Document doc = XML.getDOMImplementation().createDocument(/*namespaceURI*/null, documentElementName, docType);
 		return doc;
 	}
 
 	/** The formal public identifier (FPI) of the configuration document type definition (DTD). */
 	public static final String DTD_FPI = "-//JPL//DTD EDA Configuration 1.0//EN";
 	
 	/** The old formal public identifier (FPI) of the configuration document type definition (DTD). */
 	public static final String DTD_OLD_FPI = "-//JPL//DTD OODT Configuration 1.0//EN";
 
 	/** The system identifier of the configuration document type definition (DTD). */
 	public static final String DTD_URL = "http://oodt.jpl.nasa.gov/edm-commons/Configuration.dtd";
 
 	/** Name of the system property that names the web protocol to use. */
 	public static final String WEB_PROTOCOL_PROPERTY = "org.apache.oodt.commons.Configuration.webProtocol";
 
 	/** Global properties. */
 	private Properties properties = new Properties();
 
 	/** Object context environment. */
 	Hashtable contextEnvironment = new Hashtable();
 
 	/** Exec-servers. */
 	private List execServers = new ArrayList();
 
 	/** Web server host. */
 	private String webHost;
 
 	/** Web server port. */
 	private String webPort;
 
 	/** Web server doc dir. */
 	private File webServerDocumentDirectory;
 
 	/** Name server using rir protocol.
 	 *
 	 * If false, then it's using iiop.
 	 */
 	private boolean nameServerUsingRIRProtocol;
 
 	/** Name server version. */
 	private String nameServerVersion;
 
 	/** Name server host. */
 	private String nameServerHost;
 
 	/** Name server port. */
 	private String nameServerPort;
 
 	/** Name server object key. */
 	private String nameServerObjectKey;
 
 	/** How often the name server saves its state. */
 	private int nameServerStateFrequency;
 
 	/** On what port the server manager will listen. */
 	private int serverMgrPort;
 
 	/** Thread to set a context class loader and get a JNDI initial context. */
 	private class InitialContextThread extends Thread {
 		/** Ctor
 		 *
 		 * @param loader What class loader to use as thread's context class loader.
 		 */
 		public InitialContextThread(ClassLoader loader) {
 			setContextClassLoader(loader);
 		}
 
 		public void run() {
 			try {
 				context = new InitialContext(contextEnvironment);
 			} catch (NamingException ex) {
 				exception = ex;
 			} catch (Throwable t) {
 				System.err.println("Unexpected throwable " + t.getClass().getName() + " getting initial context: "
 					+ t.getMessage());
 				t.printStackTrace();
 			}
 		}
 
 		/** Get the context.
 		 *
 		 * <strong>Warning!</strong> Do not call this method until the thread terminates.
 		 *
 		 * @return The context, or null if the context could not be retrieved.
 		 */
 		public Context getContext() {
 			return context;
 		}
 
 		/** Get any exception.
 		 *
 		 * @return Any exception that occurred while retrieving the context.
 		 */
 		public NamingException getException() {
 			return exception;
 		}
 
 		/** JNDI context. */
 		private Context context;
 
 		/** Any exception. */
 		private NamingException exception;
 	}
 }