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* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements.  The ASF licenses this file to You
* under the Apache License, Version 2.0 (the "License"); you may not
* use this file except in compliance with the License.
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*
*     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,
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* copyright in this work, please see the NOTICE file in the top level
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*/
package org.apache.abdera.factory;

import org.apache.abdera.model.Base;
import org.apache.abdera.model.Element;

/**
 * 
 *   Extension Factories are used to provide a means of dynamically resolving
 *   builders for namespaced extension elements
 * 
 *
 * There are four ways of supporting extension elements.
 * 
 * 
 *   Implement your own Factory (hard)
 *   Subclass the default Axiom-based Factory (also somewhat difficult)
 *   Implement and register an ExtensionFactory (wonderfully simple)
 *   Use the Feed Object Model's dynamic support for extensions (also very simple)
 * 
 * 
 * 
 *   Registering an Extension Factory requires generally nothing more than 
 *   implementing ExtensionFactory and then creating a file called 
 *   META-INF/services/org.apache.abdera.factory.ExtensionFactory and listing
 *   the class names of each ExtensionFactory you wish to register.
 * 
 *
 * ExtensionFactory implementations are assumed to be threadsafe
 */
public interface ExtensionFactory {

  /**
   * Returns true if this extension factory handles the specified namespace
   * 
   * @param namespace The XML namespace of the extension
   * @return True if the namespace is supported by the ExtensionFactory
   */
  boolean handlesNamespace(String namespace);

  /**
   * Returns the Namespace URIs handled by this Extension Factory
   *
   * @return A List of Namespace URIs Supported by this Extension
   */
  String[] getNamespaces();

  /**
   * Abdera's support for static extensions is based on a simple delegation
   * model.  Static extension interfaces wrap the dynamic extension
   * API. ExtensionFactory's are handed the internal dynamic element 
   * instance and are expected to hand back an object wrapper.  
   * 
   * @param internal The Abdera element that needs to be wrapped
   * @return The wrapper element
   */
  T getElementWrapper(Element internal);
  
  /**
   * Retrieve the mime type for the element
   * 
   * @param base An Abdera object
   * @return A MIME media type for the object
   */
  String getMimeType(T base);
}