org.zkoss.zk.ui.sys

Interface FailoverManager

public interface FailoverManager

Represents a class that is able to handle fail-over in the application specific way.

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.

If you want to use the Web server's clustering feature, what you need to do is to specify SerializableUiFactory as the UI factory in zk.xml as follows (and forget FailoverManager).

<system-config>
 <ui-factory-class>org.zkoss.zk.ui.http.SerializableUiFactory</ui-factory-class>
</system-config>

The recovery involves two phases:

1. isRecoverable(org.zkoss.zk.ui.Session, java.lang.String): It tests whether the desktop is recoverable.
2. recover(org.zkoss.zk.ui.Session, org.zkoss.zk.ui.Execution, org.zkoss.zk.ui.Desktop): If recoverable, ZK will create the desktop accordingly, prepare the execution and then invoke this method to do real recovery.

Author:

tomyeh

Method Summary

Methods

Modifier and Type	Method and Description
boolean	isRecoverable(Session sess, java.lang.String desktopId) Tests whether the specified desktop ID is recoverable.
void	recover(Session sess, Execution exec, Desktop desktop) Recovers the specified desktop.
void	start(WebApp wapp) Starts the failover manager.
void	stop(WebApp wapp) Stops the failover manager.

Method Detail

start

void start(WebApp wapp)

Starts the failover manager.

Since:

5.0.0

stop

void stop(WebApp wapp)

Stops the failover manager. Called only if the server is about to stop.

Since:

5.0.0

isRecoverable

boolean isRecoverable(Session sess,
                    java.lang.String desktopId)

Tests whether the specified desktop ID is recoverable.

Note: when this method called, no execution (Execution) is available. The implementation shall only check whether it is possible to recover the specified desktop ID. Then, do the real recovery in recover(org.zkoss.zk.ui.Session, org.zkoss.zk.ui.Execution, org.zkoss.zk.ui.Desktop).

Parameters:

sess - the session

desktopId - the desktop ID to recover

recover

void recover(Session sess,
           Execution exec,
           Desktop desktop)
             throws UiException

Recovers the specified desktop. It is called only when isRecoverable(org.zkoss.zk.ui.Session, java.lang.String) returns true. Before calling this method, the desktop and execution Execution) are all prepared.

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.

During the recovering process, you have to do the following:

Recover Desktop

• [must] Call DesktopCtrl.setId(java.lang.String) to correct the desktop ID.
• [optional] Call Desktop.setCurrentDirectory(java.lang.String) to correct the current directory. It is the directory of the path of the ZUML page.
• [optional] Call Desktop.setDeviceType(java.lang.String) to correct the device type (default: html).
• [Must] Recover all pages and components.
• [Optional] Recover the response ID by use of DesktopCtrl.setResponseId(int).
• [Optional] Recover desktop's attributes.

Recover Page

• [Must] Invoke 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 Page.
• [Must] Then, invoke PageCtrl.init(org.zkoss.zk.ui.sys.PageConfig) to initialized the page.
• [Optional] Recover page's attributes.

Throws:

UiException - if failed to recover