/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at
 * trunk/opends/resource/legal-notices/OpenDS.LICENSE
 * or https://OpenDS.dev.java.net/OpenDS.LICENSE.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at
 * trunk/opends/resource/legal-notices/OpenDS.LICENSE.  If applicable,
 * add the following below this CDDL HEADER, with the fields enclosed
 * by brackets "[]" replaced with your own identifying information:
 *      Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 *
 *
 *      Copyright 2006-2008 Sun Microsystems, Inc.
 */
package org.opends.server.api;

import org.opends.messages.Message;

import java.util.List;
import org.opends.server.admin.std.server.ExtensionCfg;
import org.opends.server.config.ConfigException;
import org.opends.server.types.InitializationException;



/**
 * This class defines the set of methods and structures that must be
 * implemented by a Directory Server extension.
 *
 * @param <T>
 *          The type of extension configuration handled by
 *          this extension implementation.
 */
@org.opends.server.types.PublicAPI(
     stability=org.opends.server.types.StabilityLevel.VOLATILE,
     mayInstantiate=false,
     mayExtend=true,
     mayInvoke=true)
public abstract class Extension
       <T extends ExtensionCfg>
{
  /**
   * Initializes this extension based on the
   * information in the provided extension configuration.
   *
   * @param configuration
   *          The extension configuration that contains the
   *          information to use to initialize this connection
   *          handler.
   * @throws ConfigException
   *           If an unrecoverable problem arises in the process of
   *           performing the initialization as a result of the server
   *           configuration.
   * @throws InitializationException
   *           If a problem occurs during initialization that is not
   *           related to the server configuration.
   */
  public abstract void initializeExtension(T configuration)
      throws ConfigException, InitializationException;



  /**
   * Indicates whether the provided configuration is acceptable for
   * this extension.  It should be possible to call this
   * method on an uninitialized extension instance in order
   * to determine whether the extension would be able to use
   * the provided configuration.
   * <BR><BR>
   * Note that implementations which use a subclass of the provided
   * configuration class will likely need to cast the configuration
   * to the appropriate subclass type.
   *
   * @param  configuration        The extension configuration
   *                              for which to make the determination.
   * @param  unacceptableReasons  A list that may be used to hold the
   *                              reasons that the provided
   *                              configuration is not acceptable.
   *
   * @return  {@code true} if the provided configuration is acceptable
   *          for this extension, or {@code false} if not.
   */
  public boolean isConfigurationAcceptable(
                      ExtensionCfg configuration,
                      List<Message> unacceptableReasons)
  {
    // This default implementation does not perform any special
    // validation.  It should be overridden by extension
    // implementations that wish to perform more detailed validation.
    return true;
  }



  /**
   * Performs any finalization that may be necessary for
   * this extension.
   *
   */
  public abstract void finalizeExtension();

 }