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/***********************************************************************************************************************
 *
 * blueMarine Metadata - open source media workflow
 * Copyright (C) 2007-2011 by Tidalwave s.a.s. (http://www.tidalwave.it)
 *
 ***********************************************************************************************************************
 *
 * 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.
 *
 ***********************************************************************************************************************
 *
 * WWW: http://bluemarine.tidalwave.it
 * SCM: https://kenai.com/hg/bluemarine~metadata-src
 *
 **********************************************************************************************************************/
package it.tidalwave.metadata.spi;

import it.tidalwave.metadata.Metadata;
import it.tidalwave.metadata.MetadataItemHolder;
import javax.annotation.Nonnull;

/*******************************************************************************
 *
 * This class makes it possible for service providers to intercept the creation
 * of a new metadata item (so, for instance, it can be managed by a persistence
 * service or similar). Implementations just need to register through the
 * META-INF/services mechanism. Each interceptor must declare the
 * class of the items that it is able to manage.
 *
 * note       Notifies Items life cycle
 * @stereotype listener
 *
 * @author  Fabrizio Giudici
 * @version $Id$
 *
 ******************************************************************************/
public interface MetadataItemInterceptor
  {
    /***************************************************************************
     *
     * Returns the class of the items that this interceptor is willing to manage.
     * 
     * @return   the managed class
     * 
     **************************************************************************/
    @Nonnull 
    public Class getItemClass();
    
    /***************************************************************************
     *
     * Notifies that a certain metadata item has been created.
     * 
     * @param  metadata      the {@link Metadata} owning the item
     * @param  holder        the holder of the metadata item
     * 
     **************************************************************************/
    public void notifyItemCreated (@Nonnull Metadata metadata, @Nonnull MetadataItemHolder holder)
      throws Exception;

    // There's no notifyItemRemoved() since metadata items are never removed;
    // eventually, they just become empty. 
  }