java.lang.Object
- org.jivesoftware.openfire.cluster.ClusterMonitor

All Implemented Interfaces:

ClusterEventListener, Module
```
public class ClusterMonitor
extends Object
implements Module, ClusterEventListener
```
Monitors the state of the cluster, and warns admins when nodes leave or rejoin the cluster

Constructor Summary

Constructors
Constructor Description

ClusterMonitor()

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`void`	`destroy()`	Module should free all resources and prepare for deallocation.
`String`	`getName()`	Returns the name of the module for display in administration interfaces.
`void`	`initialize(XMPPServer xmppServer)`	Initialize the module with the container.
`void`	`joinedCluster()`	Notification event indicating that this JVM is now part of a cluster.
`void`	`joinedCluster(byte[] nodeIdBytes)`	Notification event indicating that another JVM is now part of a cluster.
`void`	`leftCluster()`	Notification event indicating that this JVM is no longer part of the cluster.
`void`	`leftCluster(byte[] nodeIdBytes)`	Notification event indicating that another JVM is no longer part of the cluster.
`void`	`markedAsSeniorClusterMember()`	Notification event indicating that this JVM is now the senior cluster member.
`void`	`start()`	Start the module (must return quickly).
`void`	`stop()`	Stop the module.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - ClusterMonitor
```
public ClusterMonitor()
```
- Method Detail
  - getName
```
public String getName()
```
    Description copied from interface: Module
    
    Returns the name of the module for display in administration interfaces.
    
    Specified by:
    
    getName in interface Module
    
    Returns:
    
    The name of the module.
  - initialize
```
public void initialize(XMPPServer xmppServer)
```
    Description copied from interface: Module
    
    Initialize the module with the container. Modules may be initialized and never started, so modules should be prepared for a call to destroy() to follow initialize().
    
    Specified by:
    
    initialize in interface Module
    
    Parameters:
    
    xmppServer - the server hosting this module.
  - start
```
public void start()
```
    Description copied from interface: Module
    
    Start the module (must return quickly). Any long running operations should spawn a thread and allow the method to return immediately.
    
    Specified by:
    
    start in interface Module
  - stop
```
public void stop()
```
    Description copied from interface: Module
    
    Stop the module. The module should attempt to free up threads and prepare for either another call to initialize (reconfigure the module) or for destruction.
    
    Specified by:
    
    stop in interface Module
  - destroy
```
public void destroy()
```
    Description copied from interface: Module
    
    Module should free all resources and prepare for deallocation.
    
    Specified by:
    
    destroy in interface Module
  - joinedCluster
```
public void joinedCluster()
```
    Description copied from interface: ClusterEventListener
    Notification event indicating that this JVM is now part of a cluster. At this point the XMPPServer.getNodeID() holds the new nodeID value.
    When joining the cluster as the senior cluster member the ClusterEventListener.markedAsSeniorClusterMember() event will be sent right after this event.
    
    At this point the CacheFactory holds clustered caches. That means that modifications to the caches will be reflected in the cluster. The clustered caches were just obtained from the cluster and no local cached data was automatically moved.
    It is generally advisable that implementations of this method:
    
    enrich clustered cache data, by (re)adding data from this JVM/cluster node to relevant caches
    
    invoke applicable event listeners, to reflect changes in availability of data on other cluster nodes.
    Specified by:
    
    joinedCluster in interface ClusterEventListener
  - joinedCluster
```
public void joinedCluster(byte[] nodeIdBytes)
```
    Description copied from interface: ClusterEventListener
    
    Notification event indicating that another JVM is now part of a cluster.
    At this point the CacheFactory of the new node holds clustered caches. That means that modifications to the caches of this JVM will be reflected in the cluster and in particular in the new node.
    
    Specified by:
    
    joinedCluster in interface ClusterEventListener
    
    Parameters:
    
    nodeIdBytes - ID of the node that joined the cluster.
  - leftCluster
```
public void leftCluster()
```
    Description copied from interface: ClusterEventListener
    Notification event indicating that this JVM is no longer part of the cluster. This could happen when disabling clustering support, removing the enterprise plugin that provides clustering support or connection to cluster got lost.
    Moreover, if we were in a "split brain" scenario (ie. separated cluster islands) and the island were this JVM belonged was marked as "old" then all nodes of that island will get the left cluster event and joined cluster events. That means that caches will be reset and thus will need to be repopulated again with fresh data from this JVM. This also includes the case where this JVM was the senior cluster member and when the islands met again then this JVM stopped being the senior member.
    At this point the CacheFactory holds local caches. That means that modifications to the caches will only affect this JVM. It is generally advisable that implementations of this method:
    
    restore relevant caches content, by repopulating the caches with data from this JVM/cluster node
    
    invoke applicable event listeners, to reflect changes in availability of data on other cluster nodes.
    Specified by:
    
    leftCluster in interface ClusterEventListener
  - leftCluster
```
public void leftCluster(byte[] nodeIdBytes)
```
    Description copied from interface: ClusterEventListener
    
    Notification event indicating that another JVM is no longer part of the cluster. This could happen when disabling clustering support, removing the enterprise plugin that provides clustering support or connection to cluster got lost.
    Moreover, if we were in a "split brain" scenario (ie. separated cluster islands) and the island were the other JVM belonged was marked as "old" then all nodes of that island will get the left cluster event and joined cluster events. That means that caches will be reset and thus will need to be repopulated again with fresh data from this JVM. This also includes the case where the other JVM was the senior cluster member and when the islands met again then the other JVM stopped being the senior member.
    At this point the CacheFactory of the leaving node holds local caches. That means that modifications to the caches of this JVM will not affect the leaving node but other cluster members. It is generally advisable that implementations of this method invoke applicable event listeners, to reflect changes in availability of data (related to the node that left). Often, this action is orchestrated by only one of the remaining cluster nodes: the senior member.
    
    Specified by:
    
    leftCluster in interface ClusterEventListener
    
    Parameters:
    
    nodeIdBytes - ID of the node that is left the cluster.
  - markedAsSeniorClusterMember
```
public void markedAsSeniorClusterMember()
```
    Description copied from interface: ClusterEventListener
    
    Notification event indicating that this JVM is now the senior cluster member. This could either happen when initially joining the cluster or when the senior cluster member node left the cluster and this JVM was marked as the new senior cluster member.
    Moreover, in the case of a "split brain" scenario (ie. separated cluster islands) each island will have its own senior cluster member. However, when the islands meet again there could only be one senior cluster member so one of the senior cluster members will stop playing that role. When that happens the JVM no longer playing that role will receive the ClusterEventListener.leftCluster() and ClusterEventListener.joinedCluster() events.
    
    Specified by:
    
    markedAsSeniorClusterMember in interface ClusterEventListener

Class ClusterMonitor

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

ClusterMonitor

Method Detail

getName

initialize

start

stop

destroy

joinedCluster

joinedCluster

leftCluster

leftCluster

markedAsSeniorClusterMember