castorregistryservice.java

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/*
 * Copyright 2000-2001,2004 The Apache Software Foundation.
 * 
 * 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.apache.jetspeed.services.registry;

// Jetspeed stuff
import org.apache.jetspeed.services.logging.JetspeedLogFactoryService;
import org.apache.jetspeed.services.logging.JetspeedLogger;
import org.apache.jetspeed.om.registry.Registry;
import org.apache.jetspeed.om.registry.RegistryEntry;
import org.apache.jetspeed.om.registry.RegistryException;
import org.apache.jetspeed.om.registry.base.BaseRegistry;
import org.apache.jetspeed.om.registry.base.LocalRegistry;

//turbine stuff
import org.apache.turbine.services.InitializationException;
import org.apache.turbine.services.TurbineBaseService;
import org.apache.turbine.services.TurbineServices;
import org.apache.turbine.services.servlet.TurbineServlet;
import org.apache.turbine.services.servlet.ServletService;
import org.apache.turbine.services.resources.ResourceService;

// castor marshalling
import org.exolab.castor.mapping.Mapping;
import org.exolab.castor.xml.Unmarshaller;
import org.exolab.castor.xml.Marshaller;
import org.xml.sax.InputSource;
import org.apache.xml.serialize.Serializer;
import org.apache.xml.serialize.XMLSerializer;
import org.apache.xml.serialize.OutputFormat;
import org.w3c.dom.Document;
import org.w3c.dom.Node;

//java stuff
import java.io.File;
import java.io.FileFilter;
import java.io.FileReader;
import java.io.FileOutputStream;
import java.io.OutputStreamWriter;
import java.io.Reader;
import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Map;
import java.util.Iterator;
import java.util.Vector;
import javax.servlet.ServletConfig;
import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;

/**
 * <p>This is an implementation of the <code>RegistryService</code>
 * based on the Castor XML serialization mechanisms</p>
 * <p>This registry aggregates multiple RegistryFragment to store the regsistry
 * entries</p>
 *
 * <p>This service expects the following properties to be set for correct operation:
 * <dl>
 *    <dt>directory</dt><dd>The directory where the Registry will look for
 *    fragment files</dd>
 *    <dt>extension</dt><dd>The extension used for identifying the registry fragment
 *    files. Default .xreg</dd>
 *    <dt>mapping</dt><dd>the Castor object mapping file path</dd>
 *    <dt>registries</dt><dd>a comma separated list of registry names to load
 *     from this file</dd>
 *    <dt>refreshRate</dt><dd>Optional. The manager will check every
 *     refreshRate seconds if the config has changed and if true will refresh
 *     all the registries. A value of 0 or negative will disable the
 *     automatic refresh operation. Default: 300 (5 minutes)</dd>
  * </dl>
 * </p>
 *
 * @author <a href="mailto:[e-mail]">Rapha雔 Luta</a>
 * @author <a href="mailto:[e-mail]">Santiago Gala</a>
 * @version $Id: CastorRegistryService.java,v 1.37 2004/03/31 00:23:02 jford Exp $
 */
public class CastorRegistryService
    extends TurbineBaseService
    implements RegistryService, FileRegistry
{
    /**
     * Static initialization of the logger for this class
     */    
    private static final JetspeedLogger logger = JetspeedLogFactoryService.getLogger(CastorRegistryService.class.getName());
    
    public static final int DEFAULT_REFRESH = 300;
    public static final String DEFAULT_EXTENSION = ".xreg";
    public static final String DEFAULT_MAPPING = "${webapp}/WEB-INF/conf/mapping.xml";

    /** regsitry type keyed list of entries */
    private Hashtable registries = new Hashtable();

    /** The Castor generated RegsitryFragment objects */
    private Hashtable fragments = new Hashtable();

    /** The list of default fragments stores for newly created objects */
    private Hashtable defaults = new Hashtable();

    /** Associates entries with their fragments name for quick lookup */
    private Hashtable entryIndex = new Hashtable();

    /** the Watcher object which monitors the regsitry directory */
    private RegistryWatcher watcher = null;

    /** the Castor mapping file name */
    private Mapping mapping = null;

    /** the output format for pretty printing when saving registries */
    private OutputFormat format = null;

    /** the base regsitry directory */
    private String directory = null;

    /** the extension for registry files */
    private String extension = null;

    /**
     * Returns a Registry object for further manipulation
     *
     * @param regName the name of the registry to fetch
     * @return a Registry object if found by the manager or null
     */
    public Registry get(String regName)
    {
        return (Registry) registries.get(regName);
    }

    /**
     *  List all the registry currently available to this service
     *
     * @return an Enumeration of registry names.
     */
    public Enumeration getNames()
    {
        return registries.keys();
    }

    /**
     * Creates a new RegistryEntry instance compatible with the current
     * Registry instance implementation
     *
     * @param regName the name of the registry to use
     * @return the newly created RegistryEntry
     */
    public RegistryEntry createEntry(String regName)
    {
                RegistryEntry entry = null;
        Registry registry = (Registry) registries.get(regName);

        if (registry != null)
        {
            entry = registry.createEntry();
        }

        return entry;
    }

    /**
     * Returns a RegistryEntry from the named Registry.
     * This is a convenience wrapper around {@link
     * org.apache.jetspeed.om.registry.Registry#getEntry }
     *
     * @param regName the name of the registry
     * @param entryName the name of the entry to retrieve from the
     *                  registry
     * @return a RegistryEntry object if the key is found or null
     */
    public RegistryEntry getEntry(String regName, String entryName)
    {
        try
        {
            return ((Registry) registries.get(regName)).getEntry(entryName);
        }
        catch (RegistryException e)
        {
            if (logger.isInfoEnabled())
            {
                logger.info("RegistryService: Failed to retrieve " + entryName + " from " + regName);
            }
        }
        catch (NullPointerException e)
        {
            logger.error("RegistryService: " + regName + " registry is not known ", e);
        }

        return null;
    }

    /**
     * Add a new RegistryEntry in the named Registry.
     * This is a convenience wrapper around {@link
     * org.apache.jetspeed.om.registry.Registry#addEntry }
     *
     * @param regName the name of the registry
     * @param entry the Registry entry to add
     * @exception Sends a RegistryException if the manager can't add
     *            the provided entry
     */
    public void addEntry(String regName, RegistryEntry entry) throws RegistryException
    {
        if (entry == null)
        {
            return;
        }

		LocalRegistry registry = (LocalRegistry) registries.get(regName);

        if (registry != null)
        {
            String fragmentName = (String) entryIndex.get(entry.getName());

            if (fragmentName == null)
            {
                // either the entry was deleted or it does not exist
                // in both cases, use the default fragment
                fragmentName = (String) defaults.get(regName);
            }

            RegistryFragment fragment = (RegistryFragment) fragments.get(fragmentName);

            //Fragment can be (and sometimes is, but should not be) null
            if (fragment == null)
            {
                fragment = new RegistryFragment();
                fragment.put(regName, new Vector());
                fragments.put(fragmentName, fragment);
            }
            else
            {
                Vector vectRegistry = (Vector) fragment.get(regName);
                if (vectRegistry == null)
                {
                    fragment.put(regName, new Vector());
                }
            }

            synchronized (entryIndex)
            {
                if (registry.hasEntry(entry.getName()))
                {
                    fragment.setEntry(regName, entry);
                    registry.setLocalEntry(entry);
                }
                else
                {
                    fragment.addEntry(regName, entry);
                    registry.addLocalEntry(entry);
                }

                entryIndex.put(entry.getName(), fragmentName);
                // mark this fragment so that it's persisted next time
                // the registry watcher is running
                fragment.setDirty(true);
            }
        }
    }

    /**
     * Deletes a RegistryEntry from the named Registry
     * This is a convenience wrapper around {@link
     * org.apache.jetspeed.om.registry.Registry#removeEntry }
     *
     * @param regName the name of the registry
     * @param entryName the name of the entry to remove
     */
    public void removeEntry(String regName, String entryName)
    {
        if (entryName == null)
        {
            return;
        }

		LocalRegistry registry = (LocalRegistry) registries.get(regName);

        if (registry != null)
        {
            String fragmentName = (String) entryIndex.get(entryName);

            if (fragmentName != null)
            {
                RegistryFragment fragment = (RegistryFragment) fragments.get(fragmentName);

                synchronized (entryIndex)
                {
                    fragment.removeEntry(regName, entryName);
                    entryIndex.remove(entryName);

                    // mark this fragment so that it's persisted next time
                    // the registry watcher is running
                    fragment.setDirty(true);
                }
            }

            // the entry is physically removed, remove the dangling reference
            registry.removeLocalEntry(entryName);
        }
    }

    /**
     * This is the early initialization method called by the
     * Turbine <code>Service</code> framework
     */
    public synchronized void init(ServletConfig conf) throws InitializationException
    {

        //Ensure that the servlet service is initialized
        TurbineServices.getInstance().initService(ServletService.SERVICE_NAME, conf);

        ResourceService serviceConf = ((TurbineServices) TurbineServices.getInstance())
                                                     .getResources(RegistryService.SERVICE_NAME);
        String mapFile = null;
        Vector names = new Vector();
        int refreshRate = 0;

        // read the configuration keys
        try
        {
            directory = serviceConf.getString("directory");
            mapFile = serviceConf.getString("mapping", DEFAULT_MAPPING);
            extension = serviceConf.getString("extension", DEFAULT_EXTENSION);
            refreshRate = serviceConf.getInt("refreshRate", DEFAULT_REFRESH);

            mapFile = TurbineServlet.getRealPath(mapFile);
            directory = TurbineServlet.getRealPath(directory);
        }
        catch (Throwable t)
        {
            throw new InitializationException("Unable to initialize CastorRegistryService, missing config keys");
        }

        // build the map of default fragments, eahc registry must be associated
        // with at least one fragment
        try
        {
            ResourceService defaults = serviceConf.getResources("default");
            Iterator i = defaults.getKeys();
            while (i.hasNext())
            {
                String name = (String) i.next();
                String fragmentFileName = defaults.getString(name);

                String absFileName = new File(directory, fragmentFileName + extension).getCanonicalPath();
                // add this name in the list of available registries
                names.add(name);

                // store the default file mapping
                this.defaults.put(name, absFileName);
            }
        }
        catch (Exception e)
        {
            logger.error("RegistryService: Registry init error", e);
            throw new InitializationException("Unable to initialize CastorRegistryService, invalid registries definition");
        }

        // create the serializer output format
        this.format = new OutputFormat();
        format.setIndenting(true);
        format.setIndent(4);
        format.setLineWidth(0);

        // test the mapping file and create the mapping object

        if (mapFile != null)
        {
            File map = new File(mapFile);
            if (map.exists() && map.isFile() && map.canRead())
            {
                try
                {
                    mapping = new Mapping();
                    InputSource is = new InputSource(new FileReader(map));
                    is.setSystemId(mapFile);
                    mapping.loadMapping(is);
                }
                catch (Exception e)
                {
                    logger.error("RegistryService: Error in mapping creation", e);
                    throw new InitializationException("Error in mapping", e);
                }
            }
            else
            {
                throw new InitializationException("Mapping not found or not a file or unreadable: " + mapFile);
            }
        }

        // Set directory watcher if directory exists
        File base = new File(directory);
        File[] files = null;

        if (base.exists() && base.isDirectory() && base.canRead())
        {
            this.watcher = new RegistryWatcher();
            this.watcher.setSubscriber(this);
            this.watcher.setFilter(new ExtFileFilter(extension));
            if (refreshRate == 0)
            {
                this.watcher.setDone();
            }
            else
            {
                this.watcher.setRefreshRate(refreshRate);
            }
            // changing the base will trigger a synchronous loading of the fragments
            this.watcher.changeBase(base);
        }

        //Mark that we are done
        setInit(true);


        // load the registries
        Enumeration en = names.elements();

        while (en.hasMoreElements())
        {
            String name = (String) en.nextElement();
            Registry registry = (Registry) registries.get(name);

            if (registry == null)
            {
                String registryClass = null;
                try
                {
                    registryClass =
                        "org.apache.jetspeed.om.registry.base.Base"
                        + name
                        + "Registry";

                    registry = (Registry) Class.forName(registryClass).newInstance();
                }
                catch (Exception e)
                {
                    if (logger.isWarnEnabled())
                    {
                        logger.warn("RegistryService: Class "
                                    + registryClass
                                    + " not found, reverting to default Registry");
                    }
                    registry = new BaseRegistry();
                }