/* FailoverManager.java
Purpose:
Description:
History:
Wed Mar 28 14:39:26 2007, Created by tomyeh
Copyright (C) 2007 Potix Corporation. All Rights Reserved.
{{IS_RIGHT
This program is distributed under LGPL Version 2.1 in the hope that
it will be useful, but WITHOUT ANY WARRANTY.
}}IS_RIGHT
*/
package org.zkoss.zk.ui.sys;
import org.zkoss.zk.ui.Desktop;
import org.zkoss.zk.ui.Execution;
import org.zkoss.zk.ui.Session;
import org.zkoss.zk.ui.UiException;
import org.zkoss.zk.ui.WebApp;
/**
* Represents a class that is able to handle fail-over in the
* application specific way.
*
* <p>Desktops, pages and components are serializables, so you can use
* the clustering feature supported by the Web server without implementing
* this interface. In other words, you need to implement this interface
* only if you want to provide an application-specific way to re-create
* back.
*
* <p>If you want to use the Web server's clustering feature,
* what you need to do is to specify {@link org.zkoss.zk.ui.http.SerializableUiFactory}
* as the UI factory in zk.xml as follows (and forget {@link FailoverManager}).
*
* <pre><code>
<system-config>
<ui-factory-class>org.zkoss.zk.ui.http.SerializableUiFactory</ui-factory-class>
</system-config>
</code></pre>
*
* <p>The recovery involves two phases:
*<ol>
*<li>{@link #isRecoverable}: It tests whether the desktop is recoverable.</li>
*<li>{@link #recover}: If recoverable,
* ZK will create the desktop accordingly, prepare the execution
* and then invoke this method to do real recovery.<li>
*</ol>
*
* @author tomyeh
*/
public interface FailoverManager {
/** Starts the failover manager.
* @since 5.0.0
*/
public void start(WebApp wapp);
/** Stops the failover manager.
* Called only if the server is about to stop.
* @since 5.0.0
*/
public void stop(WebApp wapp);
/** Tests whether the specified desktop ID is recoverable.
*
* <p>Note: when this method called, no execution
* ({@link Execution}) is available.
* The implementation shall only check whether it is possible to
* recover the specified desktop ID.
* Then, do the real recovery in {@link #recover}.
*
* @param sess the session
* @param desktopId the desktop ID to recover
*/
public boolean isRecoverable(Session sess, String desktopId);
/** Recovers the specified desktop.
* It is called only when {@link #isRecoverable} returns true.
* Before calling this method, the desktop and execution
* {@link Execution}) are all prepared.
*
* <p>Note: ZK assumes the failover manager can recover the desktop
* completely, so it won't update the browser whatever have been done
* in this method.
*
* <p>During the recovering process, you have to do the following:
*
* <p><b>Recover Desktop</b></p>
* <ul>
* <li>[must] Call {@link DesktopCtrl#setId} to correct the desktop ID.</li>
* <li>[optional] Call {@link Desktop#setCurrentDirectory} to
* correct the current directory.
* It is the directory of the path of the ZUML page.</li>
* <li>[optional] Call {@link Desktop#setDeviceType} to correct
* the device type (default: html).</li>
* <li>[Must] Recover all pages and components.</li>
* <li>[Optional] Recover the response ID by use of
* {@link DesktopCtrl#setResponseId}.</li>
* <li>[Optional] Recover desktop's attributes.</li>
* </ul>
*
* <p><b>Recover Page</b></p>
* <ul>
* <li>[Must] Invoke {@link org.zkoss.zk.ui.impl.PageImpl#PageImpl(org.zkoss.zk.ui.metainfo.LanguageDefinition, org.zkoss.zk.ui.metainfo.ComponentDefinitionMap, String, String)}
* (or your own implementation) to create an instance of {@link org.zkoss.zk.ui.Page}.</li>
* <li>[Must] Then, invoke {@link org.zkoss.zk.ui.sys.PageCtrl#init} to initialized the page.</li>
* <li>[Optional] Recover page's attributes.</li>
* </ul>
*
* @exception UiException if failed to recover
*/
public void recover(Session sess, Execution exec, Desktop desktop) throws UiException;
}