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/* 
 * This file is part of the Echo Web Application Framework (hereinafter "Echo").
 * Copyright (C) 2002-2009 NextApp, Inc.
 *
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (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.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
 * the terms of any one of the MPL, the GPL or the LGPL.
 */

package nextapp.echo.webcontainer;

import java.util.Iterator;

import nextapp.echo.app.Command;
import nextapp.echo.app.util.Context;

/**
 * A stateless peer object used to render the given type of 
 * nextapp.echo.app.Command to the client.
 * 
 * A single instance of a given 
 * CommandSynchronizePeer will be created to synchronize the state 
 * of ALL instances of a particular class of 
 * Command.  Thus, it is not possible to
 * store information about a command's state in this object.
 */
public interface CommandSynchronizePeer {
    
    /**
     * Returns the remote client component name.
     */
    public String getClientCommandType();

    /**
     * Returns the Class of Command
     * supported by this peer.
     * 
     * @return the Class
     */
    public Class getCommandClass();
    
    /**
     * Returns the value of a specific property.
     * 
     * @param context the relevant Context, provides 
     *        standard contextual information described in class description, in
     *        addition to the following:
     *        

     *         ServerMessage
     *        
     * @param command the Command being rendered
     * @param propertyName the name of the property being rendered
     * @param propertyIndex the property index (only relevant for indexed properties, -1 will
     *        be provided for non-indexed properties)
     * @return the property value
     */
    public Object getProperty(Context context, Command command, String propertyName, int propertyIndex);
    
    /**
     * Determines which indices of a particular property are set.
     * This method will only be invoked on properties where
     * isPropertyIndexed() has returned true.
     * 
     * @param context the relevant Context, provides 
     *        standard contextual information described in class description, in
     *        addition to the following:
     *        
     *         ServerMessage
     *        
     * @param command the command
     * @param propertyName the property name
     * @return an Iterator that returns the set indices in
     *         incrementing order as Integers
     */
    public Iterator getPropertyIndices(Context context, Command command, String propertyName);
    
    /**
     * Returns an Iterator over the collection of names of all
     * output properties that should be rendered to the remote client. Only the
     * names of properties with non-default values should be returned.
     * 
     * @param context the relevant Context, provides 
     *        standard contextual information described in class description, in
     *        addition to the following:
     *        
     *         ServerMessage
     *        
     * @param command the command
     * @return an Iterator of property names
     */
    public Iterator getPropertyNames(Context context, Command command);
    
    /**
     * Initializes the peer.
     * This method will be invoked prior to rendering a specific
     * Command for the first time.
     * 
     * @param context the relevant Context, provides 
     *        standard contextual information described in class description, in
     *        addition to the following:
     *        
     *         ServerMessage
     *        
     */
    public void init(Context context);
    
    /**
     * Determines if the specified output property is indexed.
     * 
     * @param context the relevant Context, provides 
     *        standard contextual information described in class description, in
     *        addition to the following:
     *        
     *         ServerMessage
     *        
     * @param command the command
     * @param propertyName the property name
     * @return true if the property is indexed
     */
    public boolean isPropertyIndexed(Context context, Command command, String propertyName);
}