    001package org.apache.turbine.services.uniqueid;
    002
    003
    004/*
    005 * Licensed to the Apache Software Foundation (ASF) under one
    006 * or more contributor license agreements.  See the NOTICE file
    007 * distributed with this work for additional information
    008 * regarding copyright ownership.  The ASF licenses this file
    009 * to you under the Apache License, Version 2.0 (the
    010 * "License"); you may not use this file except in compliance
    011 * with the License.  You may obtain a copy of the License at
    012 *
    013 *   http://www.apache.org/licenses/LICENSE-2.0
    014 *
    015 * Unless required by applicable law or agreed to in writing,
    016 * software distributed under the License is distributed on an
    017 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    018 * KIND, either express or implied.  See the License for the
    019 * specific language governing permissions and limitations
    020 * under the License.
    021 */
    022
    023
    024import java.security.MessageDigest;
    025
    026
    027import org.apache.commons.codec.binary.Base64;
    028import org.apache.commons.logging.Log;
    029import org.apache.commons.logging.LogFactory;
    030
    031import org.apache.turbine.Turbine;
    032import org.apache.turbine.services.InitializationException;
    033import org.apache.turbine.services.TurbineBaseService;
    034import org.apache.turbine.util.GenerateUniqueId;
    035
    036/**
    037 * <p> This is an implementation of {@link UniqueIdService}.
    038 *
    039 * @author <a href="mailto:Rafal.Krzewski@e-point.pl">Rafal Krzewski</a>
    040 * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
    041 * @version $Id: TurbineUniqueIdService.java 1706239 2015-10-01 13:18:35Z tv $
    042 */
    043public class TurbineUniqueIdService
    044        extends TurbineBaseService
    045        implements UniqueIdService
    046{
    047    /** Logging */
    048    private static Log log = LogFactory.getLog(TurbineUniqueIdService.class);
    049
    050    /** The identifier of this instance of turbine. */
    051    protected static String turbineId = "UNKNOWN";
    052
    053    protected static String turbineURL = "UNKNOWN";
    054
    055    protected static int counter;
    056
    057
    058    /**
    059     * <p> Initializes the service upon first Turbine.doGet()
    060     * invocation.
    061     */
    062    @Override
    063    public void init()
    064            throws InitializationException
    065    {
    066        try
    067        {
    068            // This might be a problem if the unique Id Service runs
    069            // before Turbine got its first request. In this case,
    070            // getDefaultServerData will return just a dummy value
    071            // which is the same for all instances of Turbine.
    072            //
    073            // TODO This needs definitely further working.
    074            String url = Turbine.getDefaultServerData().toString();
    075
    076            MessageDigest md = MessageDigest.getInstance("MD5");
    077            byte [] bytesId = md.digest(url.getBytes("UTF-8"));
    078            turbineId = new String(Base64.encodeBase64(bytesId));
    079
    080            log.info("This is Turbine instance running at: " + url);
    081            log.info("The instance id is #" + turbineId);
    082            setInit(true);
    083        }
    084        catch (Exception e)
    085        {
    086            throw new InitializationException(
    087                    "Could not initialize TurbineUniqueId Service", e);
    088        }
    089    }
    090
    091    /**
    092     * <p> Writes a message to the log upon system shutdown.
    093     */
    094    @Override
    095    public void shutdown()
    096    {
    097        log.info("Turbine instance running at " + turbineURL + " shutting down.");
    098    }
    099
    100    /**
    101     * <p> Returns an identifier of this Turbine instance that is unique
    102     * both on the server and worldwide.  This identifier is computed
    103     * as an MD5 sum of the URL (including schema, address, port if
    104     * different that 80/443 respecively, context and servlet name).
    105     * There is an overwhelming probalility that this id will be
    106     * different that all other Turbine instances online.
    107     *
    108     * @return A String with the instance identifier.
    109     */
    110    public String getInstanceId()
    111    {
    112        return turbineId;
    113    }
    114
    115    /**
    116     * <p> Returns an identifier that is unique within this turbine
    117     * instance, but does not have random-like apearance.
    118     *
    119     * @return A String with the non-random looking instance
    120     * identifier.
    121     */
    122    public String getUniqueId()
    123    {
    124        int current;
    125        synchronized (TurbineUniqueIdService.class)
    126        {
    127            current = counter++;
    128        }
    129        String id = Integer.toString(current);
    130
    131        // If you manage to get more than 100 million of ids, you'll
    132        // start getting ids longer than 8 characters.
    133        if (current < 100000000)
    134        {
    135            id = ("00000000" + id).substring(id.length());
    136        }
    137        return id;
    138    }
    139
    140    /**
    141     * <p> Returns a unique identifier that looks like random data.
    142     *
    143     * @return A String with the random looking instance identifier.
    144     */
    145    public String getPseudorandomId()
    146    {
    147        return GenerateUniqueId.getIdentifier();
    148    }
    149}