Package org.forgerock.opendj.ldap

Interface LoadBalancerEventListener

All Superinterfaces:

EventListener

public interface LoadBalancerEventListener
extends EventListener

An object that registers to be notified when an LDAP client associated with a load-balancer changes state from offline to online or vice-versa, or when the failover load-balancer performs a failover or a failback.

NOTE 1: Since listeners are prone to race conditions they should only be used for monitoring and alerts. Specifically, an application should not use this mechanism to deduce whether a request can be sent or not. It should send the request and hope for the best.

NOTE 2: load-balancer implementations must ensure that only one event is sent at a time. Event listener implementations should not need to be thread safe unless they are used by multiple load balancers.

See Also:

• LdapClients.LOAD_BALANCER_EVENT_LISTENER

Field Summary

Fields

Modifier and Type	Field	Description
static final LoadBalancerEventListener	LOG_EVENTS	An event listener implementation which logs events to the LoadBalancingAlgorithm logger.
static final LoadBalancerEventListener	NO_OP	An event listener implementation which ignores all events.

Method Summary

Modifier and Type	Method	Description
void	handleFailback(LdapClient fromServer, LdapClient toServer)	Invoked when the failover load-balancer performs a failback.
void	handleFailover(LdapClient fromServer, LdapClient toServer)	Invoked when the failover load-balancer performs a failover.
void	handleLdapClientOffline(LdapClient client, LdapException error)	Invoked when the load-balancer is unable to obtain a connection from the specified LDAP client.
void	handleLdapClientOnline(LdapClient client)	Invoked when the load-balancer detects that a previously offline LDAP client is available for use again.

Field Details

LOG_EVENTS

static final LoadBalancerEventListener LOG_EVENTS

An event listener implementation which logs events to the LoadBalancingAlgorithm logger. This event listener is the default implementation configured using the LdapClients.LOAD_BALANCER_EVENT_LISTENER option.

NO_OP

static final LoadBalancerEventListener NO_OP

An event listener implementation which ignores all events.

Method Details

handleLdapClientOffline

void handleLdapClientOffline(LdapClient client,
 LdapException error)

Invoked when the load-balancer is unable to obtain a connection from the specified LDAP client. The LDAP client will be removed from the load-balancer and monitored periodically in order to determine when it is available again, at which point an online notification event will occur.

Parameters:

client - The LDAP client which has failed.

error - The last error that occurred.

handleLdapClientOnline

void handleLdapClientOnline(LdapClient client)

Invoked when the load-balancer detects that a previously offline LDAP client is available for use again.

Parameters:

client - The LDAP client which is now available for use.

handleFailover

void handleFailover(LdapClient fromServer,
 LdapClient toServer)

Invoked when the failover load-balancer performs a failover.

Parameters:

fromServer - The previous server to which all requests were routed

toServer - The new server to which all requests must be routed

handleFailback

void handleFailback(LdapClient fromServer,
 LdapClient toServer)

Invoked when the failover load-balancer performs a failback.

Parameters:

fromServer - The previous server to which all requests were routed

toServer - The new server to which all requests must be routed