org.apache.camel.component.zookeeper.policy
Class ZooKeeperRoutePolicy

java.lang.Object
  org.apache.camel.support.ServiceSupport
      org.apache.camel.impl.RoutePolicySupport
          org.apache.camel.component.zookeeper.policy.ZooKeeperRoutePolicy

All Implemented Interfaces:

ElectionWatcher, org.apache.camel.Service, org.apache.camel.ShutdownableService, org.apache.camel.spi.RoutePolicy, org.apache.camel.StatefulService, org.apache.camel.SuspendableService

public class ZooKeeperRoutePolicy
extends org.apache.camel.impl.RoutePolicySupport
implements ElectionWatcher

ZooKeeperRoutePolicy uses the leader election capabilities of a ZooKeeper cluster to control how routes are enabled. It is typically used in fail-over scenarios controlling identical instances of a route across a cluster of Camel based servers.

The policy is configured with a 'top n' number of routes that should be allowed to start, for a master/slave scenario this would be 1. Each instance of the policy will execute the election algorithm to obtain its position in the hierarchy of servers, if it is within the 'top n' servers then the policy is enabled and exchanges can be processed by the route. If not it waits for a change in the leader hierarchy and then reruns this scenario to see if it is now in the top n.

All instances of the policy must also be configured with the same path on the ZooKeeper cluster where the election will be carried out. It is good practice for this to indicate the application e.g. /someapplication/someroute/ note that these nodes should exist before using the policy.

See for more on how Leader election is archived with ZooKeeper.

Field Summary

Fields inherited from class org.apache.camel.impl.RoutePolicySupport

log

Fields inherited from class org.apache.camel.support.ServiceSupport

shutdown, shuttingdown, started, starting, stopped, stopping, suspended, suspending

Constructor Summary

ZooKeeperRoutePolicy(String uri, int enabledCount)

ZooKeeperRoutePolicy(ZooKeeperElection election)

Method Summary

void	electionResultChanged() This method is called when there is a potential change to the master.
boolean	isShouldStopConsumer()
void	onExchangeBegin(org.apache.camel.Route route, org.apache.camel.Exchange exchange)
void	setShouldStopConsumer(boolean shouldStopConsumer)

Methods inherited from class org.apache.camel.impl.RoutePolicySupport

doStart, doStop, getExceptionHandler, handleException, onExchangeDone, onInit, onRemove, onResume, onStart, onStop, onSuspend, resumeRoute, setExceptionHandler, startConsumer, startRoute, stopConsumer, stopRoute, stopRoute, suspendRoute, suspendRoute

Methods inherited from class org.apache.camel.support.ServiceSupport

doResume, doShutdown, doSuspend, getStatus, getVersion, isRunAllowed, isStarted, isStarting, isStopped, isStopping, isStoppingOrStopped, isSuspended, isSuspending, resume, shutdown, start, stop, suspend

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ZooKeeperRoutePolicy

public ZooKeeperRoutePolicy(String uri,
                            int enabledCount)

ZooKeeperRoutePolicy

public ZooKeeperRoutePolicy(ZooKeeperElection election)

Method Detail

onExchangeBegin

public void onExchangeBegin(org.apache.camel.Route route,
                            org.apache.camel.Exchange exchange)

Specified by:

onExchangeBegin in interface org.apache.camel.spi.RoutePolicy

Overrides:

onExchangeBegin in class org.apache.camel.impl.RoutePolicySupport

electionResultChanged

public void electionResultChanged()

Description copied from interface: ElectionWatcher

This method is called when there is a potential change to the master. Implementations should call "isMaster" on their ZookeeperElection instance to re-validate their status.

Specified by:

electionResultChanged in interface ElectionWatcher

isShouldStopConsumer

public boolean isShouldStopConsumer()

setShouldStopConsumer

public void setShouldStopConsumer(boolean shouldStopConsumer)