org.apache.camel.component.zookeeper.policy

Class CuratorMultiMasterLeaderRoutePolicy

java.lang.Object

org.apache.camel.support.ServiceSupport

org.apache.camel.support.RoutePolicySupport

org.apache.camel.component.zookeeper.policy.CuratorMultiMasterLeaderRoutePolicy

All Implemented Interfaces:

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

public class CuratorMultiMasterLeaderRoutePolicy
extends org.apache.camel.support.RoutePolicySupport
implements ElectionWatcher, org.apache.camel.NonManagedService

CuratorMultiMasterLeaderRoutePolicy uses Apache Curator InterProcessSemaphoreV2 receipe to implement the behavior of having at multiple active instances of a route, controlled by a specific policy, running. It is typically used in fail-over scenarios controlling identical instances of a route across a cluster of Camel based servers.

The policy affects the normal startup lifecycle of CamelContext and Routes, automatically set autoStart property of routes controlled by this policy to false. After Curator receipe identifies the current Policy instance as the Leader between a set of clients that are competing for the role, it will start the route, and only at that moment the route will start its business. This specific behavior is designed to avoid scenarios where such a policy would kick in only after a route had already been started, with the risk, for consumers for example, that some source event might have already been consumed.

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.support.RoutePolicySupport

log

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

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

Constructor Summary

Constructors

Constructor and Description
CuratorMultiMasterLeaderRoutePolicy(String uri)
CuratorMultiMasterLeaderRoutePolicy(String uri, int enabledCount)

Method Summary

Modifier and Type	Method and Description
protected void	doShutdown()
void	electionResultChanged() This method is called when there is a potential change to the master.
CuratorMultiMasterLeaderElection	getElection()
void	onInit(org.apache.camel.Route route)

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

doStart, doStop, getExceptionHandler, handleException, onExchangeBegin, onExchangeDone, onRemove, onResume, onStart, onStop, onSuspend, resumeOrStartConsumer, resumeRoute, setExceptionHandler, startConsumer, startRoute, stopConsumer, stopRoute, stopRoute, stopRouteAsync, suspendOrStopConsumer, suspendRoute, suspendRoute

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

doResume, doSuspend, getStatus, getVersion, isRunAllowed, isStarted, isStarting, isStopped, isStopping, isStoppingOrStopped, isSuspended, isSuspending, isSuspendingOrSuspended, 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

CuratorMultiMasterLeaderRoutePolicy

public CuratorMultiMasterLeaderRoutePolicy(String uri,
                                           int enabledCount)

CuratorMultiMasterLeaderRoutePolicy

public CuratorMultiMasterLeaderRoutePolicy(String uri)

Method Detail

onInit

public void onInit(org.apache.camel.Route route)

Specified by:

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

Overrides:

onInit in class org.apache.camel.support.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

doShutdown

protected void doShutdown()
                   throws Exception

Overrides:

doShutdown in class org.apache.camel.support.ServiceSupport

Throws:

Exception

getElection

public CuratorMultiMasterLeaderElection getElection()