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    1   package org.apache.turbine.services.uniqueid;
    2
    3
    4   /*
    5    * Licensed to the Apache Software Foundation (ASF) under one
    6    * or more contributor license agreements.  See the NOTICE file
    7    * distributed with this work for additional information
    8    * regarding copyright ownership.  The ASF licenses this file
    9    * to you under the Apache License, Version 2.0 (the
    10   * "License"); you may not use this file except in compliance
    11   * with the License.  You may obtain a copy of the License at
    12   *
    13   *   http://www.apache.org/licenses/LICENSE-2.0
    14   *
    15   * Unless required by applicable law or agreed to in writing,
    16   * software distributed under the License is distributed on an
    17   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    18   * KIND, either express or implied.  See the License for the
    19   * specific language governing permissions and limitations
    20   * under the License.
    21   */
    22
    23
    24  import java.security.MessageDigest;
    25
    26
    27  import org.apache.commons.codec.binary.Base64;
    28  import org.apache.commons.logging.Log;
    29  import org.apache.commons.logging.LogFactory;
    30
    31  import org.apache.turbine.Turbine;
    32  import org.apache.turbine.services.InitializationException;
    33  import org.apache.turbine.services.TurbineBaseService;
    34  import org.apache.turbine.util.GenerateUniqueId;
    35
    36  /**
    37   * <p> This is an implementation of {@link UniqueIdService}.
    38   *
    39   * @author <a href="mailto:Rafal.Krzewski@e-point.pl">Rafal Krzewski</a>
    40   * @author <a href="mailto:hps@intermeta.de">Henning P. Schmiedehausen</a>
    41   * @version $Id: TurbineUniqueIdService.java 1066925 2011-02-03 19:44:37Z ludwig $
    42   */
    43  public class TurbineUniqueIdService
    44          extends TurbineBaseService
    45          implements UniqueIdService
    46  {
    47      /** Logging */
    48      private static Log log = LogFactory.getLog(TurbineUniqueIdService.class);
    49
    50      /** The identifier of this instance of turbine. */
    51      protected static String turbineId = "UNKNOWN";
    52
    53      protected static String turbineURL = "UNKNOWN";
    54
    55      protected static int counter;
    56
    57
    58      /**
    59       * <p> Initializes the service upon first Turbine.doGet()
    60       * invocation.
    61       */
    62      @Override
    63      public void init()
    64              throws InitializationException
    65      {
    66          try
    67          {
    68              // This might be a problem if the unique Id Service runs
    69              // before Turbine got its first request. In this case,
    70              // getDefaultServerData will return just a dummy value
    71              // which is the same for all instances of Turbine.
    72              //
    73              // @todo This needs definitely further working.
    74              String url = Turbine.getDefaultServerData().toString();
    75
    76              MessageDigest md = MessageDigest.getInstance("MD5");
    77              byte [] bytesId = md.digest(url.getBytes("UTF-8"));
    78              turbineId = new String(Base64.encodeBase64(bytesId));
    79
    80              log.info("This is Turbine instance running at: " + url);
    81              log.info("The instance id is #" + turbineId);
    82              setInit(true);
    83          }
    84          catch (Exception e)
    85          {
    86              throw new InitializationException(
    87                      "Could not initialize TurbineUniqueId Service", e);
    88          }
    89      }
    90
    91      /**
    92       * <p> Writes a message to the log upon system shutdown.
    93       */
    94      @Override
    95      public void shutdown()
    96      {
    97          log.info("Turbine instance running at " + turbineURL + " shutting down.");
    98      }
    99
    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 }