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Public API for the Apache MyFaces Trinidad project
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/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  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.  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.
 */
package org.apache.myfaces.trinidad.context;

import java.io.IOException;

import java.util.Map;

import javax.faces.context.ExternalContext;

import javax.faces.context.FacesContext;

import org.apache.myfaces.trinidad.event.WindowLifecycleListener;

/**
 * 
 * Manages the set of Windows currently in the Session and allows listeners on the Windows'
 * lifecycles to be registered.
 * 
 * @see org.apache.myfaces.trinidad.context.RequestContext#getWindowManager
 */
abstract public class WindowManager
{
  /**
   * @param extContext ExternalContext so that the WindowManager may be called before the
   * FacesContext is available
   * @return The Window that contains the document making the current request
   */
  public abstract Window getCurrentWindow(ExternalContext extContext);
  
  /**
   * @param extContext ExternalContext so that the WindowManager may be called before the
   * FacesContext is available
   * @return The Unmodifiable Map of WindowIds to Windows
   */
  public abstract Map getWindows(ExternalContext extContext);

  /**
   * 
   * Registers a listener that will be informed of changes to the Lifecylce state of any of
   * the known Windows.
   * 
   * 
   * WindowLifecycleListener may be registered automatically by adding a file
   * containing the names of the classes implementing the WindowListener in a file named
   * org.apache.myfaces.trinidad.event.WindowListener inside of
   * the META_INF/services directory.
   * 
   * @param extContext ExternalContext so that the WindowManager may be called before the
   * FacesContext is available
   * @param windowListener
   */
  public abstract void addWindowLifecycleListener(
    ExternalContext extContext, WindowLifecycleListener windowListener);

  /**
   * Removes a listener that will be informed of changes to the Lifecylce state of any of
   * the known Windows
   * @param extContext ExternalContext so that the WindowManager may be called before the
   * FacesContext is available
   * @param windowListener
   */
  public abstract void removeWindowLifecycleListener(
    ExternalContext extContext, WindowLifecycleListener windowListener);

  /**
   * Performs any necessary action to embed the current window identifier into the output
   * @param context FacesContext to use to write the output
   * @throws IOException if an output exception occurs
   */
  public abstract void writeState(FacesContext context) throws IOException;
  
  /**
   * Performs any necessary action at the very beginning of the request
   * @param externalContext ExternalContext instance
   * @return true if processing of the request should continue, false otherwise
   */
  public boolean beginRequest(ExternalContext externalContext) throws IOException
  {
    return true;
  }

}