Rio Project 4.2 API Documentation

org.rioproject.fdh
Class LeaseFaultDetectionHandler

java.lang.Object
  org.rioproject.fdh.AbstractFaultDetectionHandler
      org.rioproject.fdh.LeaseFaultDetectionHandler

All Implemented Interfaces:

FaultDetectionHandler<ServiceID>

public class LeaseFaultDetectionHandler
extends AbstractFaultDetectionHandler

The LeaseFaultDetectionHandler is used to monitor services that implement the MonitorableService interface.

The LeaseFaultDetectionHandler creates a client-side Lease with the service, and attempts to renew the lease based on a configurable lease duration time. If the lease cannot be renewed and all retry attempts have failed, the LeaseFaultDetectionHandler will notify FaultDetectionListener instances of the failure.

Additionally, the LeaseFaultDetectionHandler will register with Lookup Services for ServiceRegistrar.TRANSITION_MATCH_NOMATCH transitions for the service being monitored. If the service is adminstratively removed from the network, or the service monitoring lease is between lease renewal points and the service has actually been removed from the network, the transition will be noted and FaultDetectionListener instances will be notified of the failure.

If the service does not implement the MonitorableService interface, the LeaseFaultDetectionHandler will not manage a Lease, but will only create the event consumer for Lookup Service TRANSITION_MATCH_NOMATCH transitions.

Configuring LeaseFaultDetectionHandler

This implementation of LeaseFaultDetectionHandler supports the following configuration entries; where each configuration entry name is associated with the component name org.rioproject.fdh.LeaseFaultDetectionHandler.

• leaseDuration

  Type:	long
  Default:	30*1000 (30 seconds)
  Description:	The duration of the Lease in milliseconds. The Lease renewal time will be calculated to be 75% of the LeaseTime attribute

• retryCount

  Type:	int
  Default:	3
  Description:	The number of times to retry connecting to the service when renewing the Lease. If the service cannot be reached within the retry count specified the service will be determined to be unreachable

• retryTimeout

  Type:	long
  Default:	1000 (1 second)
  Description:	How long to wait between retries (in milliseconds). This value will be used between retry attempts, waiting the specified amount of time to retry

• leasePreparer

  Type:	ProxyPreparer
  Default:	new BasicProxyPreparer()
  Description:	Preparer for the leases returned when the LeaseFaultDetectionHandler invokes the monitor method of a MonitorableService

The amount of time it takes for the StandardFaultDetectionListener to determine service failure for a service that implements the org.rioproject.core.MonitorableService interface is calculated as follows :

 ((num_retries + 1) * (connectivity_timeout)) + (retry_delay * num_retries)
 

Author:

Dennis Reedy

Nested Class Summary

Nested classes/interfaces inherited from class org.rioproject.fdh.AbstractFaultDetectionHandler

AbstractFaultDetectionHandler.ServiceMonitor

Field Summary

static long	DEFAULT_LEASE_DURATION
static String	LEASE_DURATION_KEY

Fields inherited from class org.rioproject.fdh.AbstractFaultDetectionHandler

config, configArgs, DEFAULT_RETRY_COUNT, DEFAULT_RETRY_TIMEOUT, proxy, RETRY_COUNT_KEY, RETRY_TIMEOUT_KEY, retryCount, retryTimeout, serviceMonitor, terminating

Constructor Summary

LeaseFaultDetectionHandler()

Method Summary

protected AbstractFaultDetectionHandler.ServiceMonitor	getServiceMonitor() Override parent's getServiceMonitor() method to create the ServiceLeaseManager
void	setConfiguration(String[] configArgs) Set configuration attributes for the FaultDetectionHandler.
void	setLeaseDuration(long leaseDuration)
void	setLeasePreparer(ProxyPreparer leasePreparer)

Methods inherited from class org.rioproject.fdh.AbstractFaultDetectionHandler

getName, monitor, notifyListeners, register, setRetryCount, setRetryTimeout, terminate, unregister

Methods inherited from class java.lang.Object

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

Field Detail

DEFAULT_LEASE_DURATION

public static final long DEFAULT_LEASE_DURATION

See Also:

Constant Field Values

LEASE_DURATION_KEY

public static final String LEASE_DURATION_KEY

See Also:

Constant Field Values

Constructor Detail

LeaseFaultDetectionHandler

public LeaseFaultDetectionHandler()

Method Detail

setLeaseDuration

public void setLeaseDuration(long leaseDuration)

setLeasePreparer

public void setLeasePreparer(ProxyPreparer leasePreparer)

setConfiguration

public void setConfiguration(String[] configArgs)

Description copied from interface: FaultDetectionHandler

Set configuration attributes for the FaultDetectionHandler.

Parameters:

configArgs - Configuration attributes a FaultDetectionHandler will use to monitor the service. Values are specific to a concrete instance of the FaultDetectionHandler

See Also:

FaultDetectionHandler.setConfiguration(java.lang.String[])

getServiceMonitor

protected AbstractFaultDetectionHandler.ServiceMonitor getServiceMonitor()
                                                                  throws Exception

Override parent's getServiceMonitor() method to create the ServiceLeaseManager

Specified by:

getServiceMonitor in class AbstractFaultDetectionHandler

Returns:

A ServiceMonitor

Throws:

Exception - if the ServiceMonitor cannot be created