package org.apache.ojb.broker.transaction.tm;

 /* Copyright 2004-2005 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.

  */

 import javax.transaction.TransactionManager;

 import org.apache.commons.lang.SystemUtils;

 import org.apache.ojb.broker.core.NamingLocator;

 import org.apache.ojb.broker.util.ClassHelper;

 import org.apache.ojb.broker.util.logging.Logger;

 import org.apache.ojb.broker.util.logging.LoggerFactory;

 /**

  * Abstract base class implementation of the {@link TransactionManagerFactory} interface, all

  * derived classes have to implement method {@link #getLookupInfo()}.

  *

  * @author <a href="mailto:armin@codeAuLait.de">Armin Waibel</a>

  * @version $Id: AbstractTransactionManagerFactory.java,v 1.1 2007-08-24 22:17:41 ewestfal Exp $

  */

 public abstract class AbstractTransactionManagerFactory implements TransactionManagerFactory

 {

     private static Logger log = LoggerFactory.getLogger(AbstractTransactionManagerFactory.class);

     /**

      * Returns "getTransactionManager";

      */

     public static String TM_DEFAULT_METHOD_NAME = "getTransactionManager";

     private static TransactionManager tm = null;

     /**

      * Returns an array of possible JNDI lookup / class names for

      * the {@link javax.transaction.TransactionManager} instance. An array was used

      * because for different application server versions the

      * JNDI/class name may change.

      * <p/>

      * Expect an [n][3] string array. Following arguments are available:

      * <ul>

      *    <li>info[i][0] = short description of used TM, e.g. appServer name</li>

      *    <li>info[i][2] = JNDI name to lookup TM or the method name to retrieve TM instance</li>

      *    <li>info[i][3] = if 'null' an JNDI lookup was made with JNDI name set above, if not null

      * the class name of the TM factory was assumed and the method name set above will be invoked</li>

      * </ul>

      * Example:

      * <p>

      * {{"JBoss", "java:/TransactionManager", null}};<br/>

      * In JBoss we lookup the TM via JNDI, so we don't need a TM factory class.

      * </p>

      *

      * <p>

      * {{"Websphere 4", TM_DEFAULT_METHOD_NAME, "com.ibm.ejs.jts.jta.JTSXA"},<br/>

      *    {"Websphere 5", TM_DEFAULT_METHOD_NAME, "com.ibm.ejs.jts.jta.TransactionManagerFactory"},<br/>

      *    {"Websphere >5", TM_DEFAULT_METHOD_NAME, "com.ibm.ws.Transaction.TransactionManagerFactory"}};<br/>

      * In Websphere we have to use a TM factory class and obtain the TM via a <em>getTransactionManager()</em>

      * method call. The TM factory class is varied in different versions.

      * </p>

      */

     public abstract String[][] getLookupInfo();

     /**

      * @see org.apache.ojb.broker.transaction.tm.TransactionManagerFactory

      */

     public synchronized TransactionManager getTransactionManager() throws TransactionManagerFactoryException

     {

         if (tm == null)

         {

             StringBuffer msg = new StringBuffer();

             String[][] lookupInfo = getLookupInfo();

             String EOL = SystemUtils.LINE_SEPARATOR;

             for (int i = 0; i < lookupInfo.length; i++)

             {

                 String description = lookupInfo[i][0];

                 String methodName = lookupInfo[i][1];

                 String className = lookupInfo[i][2];

                 try

                 {

                     if (className == null)

                     {

                         tm = jndiLookup(description, methodName);

                     }

                     else

                     {

                         tm = instantiateClass(description, className, methodName);

                     }

                     msg.append("Successfully requested TM for " + description + EOL);

                 }

                 catch (Exception e)

                 {

                     if (className == null)

                         msg.append("Error on TM request for " + description +

                                 ", using jndi-lookup '" + methodName + "'" + EOL + e.getMessage() + EOL);

                     else

                         msg.append("Error on TM request for " + description + ", using method '" +

                                 methodName + "' for class '" + className + "'" + EOL + e.getMessage() + EOL);

                 }

                 if (tm != null) break;

             }

             // if we don't get an TM instance throw exception

             if (tm == null)

             {

                 throw new TransactionManagerFactoryException("Can't lookup transaction manager:" + EOL + msg);

             }

         }

         return tm;

     }

     protected TransactionManager jndiLookup(String description, String methodName)

     {

         log.info(description + ", lookup TransactionManager: '" + methodName + "'");

         return (TransactionManager) NamingLocator.lookup(methodName);

     }

     protected TransactionManager instantiateClass(String description, String className, String methodName) throws Exception

     {

         log.info(description + ", invoke method '"

                 + methodName + "()' on class " + className);

         Class tmClass = ClassHelper.getClass(className);

         return (TransactionManager) tmClass.getMethod(methodName, null).invoke(null, null);

     }

 }