org.springframework.integration.handler

Class DelayHandler

java.lang.Object

org.springframework.integration.context.IntegrationObjectSupport

org.springframework.integration.handler.AbstractMessageHandler

org.springframework.integration.handler.AbstractReplyProducingMessageHandler

org.springframework.integration.handler.DelayHandler

All Implemented Interfaces:

java.util.EventListener, org.springframework.beans.factory.Aware, org.springframework.beans.factory.BeanClassLoaderAware, org.springframework.beans.factory.BeanFactoryAware, org.springframework.beans.factory.BeanNameAware, org.springframework.beans.factory.InitializingBean, org.springframework.context.ApplicationContextAware, org.springframework.context.ApplicationListener<org.springframework.context.event.ContextRefreshedEvent>, org.springframework.core.Ordered, Orderable, MessageHandler, MessageProducer, DelayHandlerManagement, TrackableComponent, NamedComponent

@ManagedResource
public class DelayHandler
extends AbstractReplyProducingMessageHandler
implements DelayHandlerManagement, org.springframework.context.ApplicationListener<org.springframework.context.event.ContextRefreshedEvent>

A MessageHandler that is capable of delaying the continuation of a Message flow based on the result of evaluation delayExpression on an inbound Message or a default delay value configured on this handler. Note that the continuation of the flow is delegated to a TaskScheduler, and therefore, the calling thread does not block. The advantage of this approach is that many delays can be managed concurrently, even very long delays, without producing a buildup of blocked Threads.

One thing to keep in mind, however, is that any active transactional context will not propagate from the original sender to the eventual recipient. This is a side-effect of passing the Message to the output channel after the delay with a different Thread in control.

When this handler's delayExpression property is configured, that evaluation result value will take precedence over the handler's defaultDelay value. The actual evaluation result value may be a long, a String that can be parsed as a long, or a Date. If it is a long, it will be interpreted as the length of time to delay in milliseconds counting from the current time (e.g. a value of 5000 indicates that the Message can be released as soon as five seconds from the current time). If the value is a Date, it will be delayed at least until that Date occurs (i.e. the delay in that case is equivalent to headerDate.getTime() - new Date().getTime()).

Since:

1.0.3

Author:

Mark Fisher, Artem Bilan

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	DelayHandler.DelayedMessageWrapper

Nested classes/interfaces inherited from class org.springframework.integration.handler.AbstractReplyProducingMessageHandler

AbstractReplyProducingMessageHandler.RequestHandler

Field Summary

Fields inherited from class org.springframework.integration.context.IntegrationObjectSupport

logger

Fields inherited from interface org.springframework.core.Ordered

HIGHEST_PRECEDENCE, LOWEST_PRECEDENCE

Constructor Summary

Constructors

Constructor and Description
DelayHandler(java.lang.String messageGroupId) Create a DelayHandler with the given 'messageGroupId' that is used as 'key' for MessageGroup to store delayed Messages in the MessageGroupStore.
DelayHandler(java.lang.String messageGroupId, org.springframework.scheduling.TaskScheduler taskScheduler) Create a DelayHandler with the given default delay.

Method Summary

Methods

Modifier and Type	Method and Description
protected void	doInit()
java.lang.String	getComponentType() Subclasses may implement this method to provide component type information.
int	getDelayedMessageCount()
protected java.lang.Object	handleRequestMessage(Message<?> requestMessage) Checks if 'requestMessage' wasn't delayed before (releaseMessageAfterDelay(org.springframework.integration.Message<?>, long) and DelayHandler.DelayedMessageWrapper).
void	onApplicationEvent(org.springframework.context.event.ContextRefreshedEvent event) Handles ContextRefreshedEvent to invoke reschedulePersistedMessages() as late as possible after application context startup.
void	reschedulePersistedMessages() Used for reading persisted Messages in the 'messageStore' to reschedule them e.g.
void	setDefaultDelay(long defaultDelay) Set the default delay in milliseconds.
void	setDelayedAdviceChain(java.util.List<org.aopalliance.aop.Advice> delayedAdviceChain) Specify the List<Advice> to advise DelayHandler.ReleaseMessageHandler proxy.
void	setDelayExpression(org.springframework.expression.Expression delayExpression) Specify the Expression that should be checked for a delay period (in milliseconds) or a Date to delay until.
void	setDelayHeaderName(java.lang.String delayHeaderName) Deprecated. in favor of delayExpression
void	setIgnoreExpressionFailures(boolean ignoreExpressionFailures) Specify whether Exceptions thrown by delayExpression evaluation should be ignored (only logged).
void	setMessageStore(MessageGroupStore messageStore) Specify the MessageGroupStore that should be used to store Messages while awaiting the delay.

Methods inherited from class org.springframework.integration.handler.AbstractReplyProducingMessageHandler

doInvokeAdvisedRequestHandler, getMessagingTemplate, handleMessageInternal, hasAdviceChain, onInit, setAdviceChain, setBeanClassLoader, setChannelResolver, setOutputChannel, setRequiresReply, setSendTimeout, shouldCopyRequestHeaders

Methods inherited from class org.springframework.integration.handler.AbstractMessageHandler

getOrder, handleMessage, setOrder, setShouldTrack

Methods inherited from class org.springframework.integration.context.IntegrationObjectSupport

afterPropertiesSet, getApplicationContextId, getBeanFactory, getComponentName, getConversionService, getIntegrationProperties, getIntegrationProperty, getTaskScheduler, setApplicationContext, setBeanFactory, setBeanName, setComponentName, setConversionService, setTaskScheduler, toString

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.springframework.integration.support.context.NamedComponent

getComponentName

Constructor Detail

DelayHandler

public DelayHandler(java.lang.String messageGroupId)

Create a DelayHandler with the given 'messageGroupId' that is used as 'key' for MessageGroup to store delayed Messages in the MessageGroupStore. The sending of Messages after the delay will be handled by registered in the ApplicationContext default ThreadPoolTaskScheduler.

See Also:

IntegrationObjectSupport.getTaskScheduler()

DelayHandler

public DelayHandler(java.lang.String messageGroupId,
            org.springframework.scheduling.TaskScheduler taskScheduler)

Create a DelayHandler with the given default delay. The sending of Messages after the delay will be handled by the provided TaskScheduler.

Method Detail

setDefaultDelay

public void setDefaultDelay(long defaultDelay)

Set the default delay in milliseconds. If no delayExpression property has been provided, the default delay will be applied to all Messages. If a delay should only be applied to Messages with evaluation result from

setDelayHeaderName

@Deprecated
public void setDelayHeaderName(java.lang.String delayHeaderName)

Deprecated. in favor of delayExpression

Specify the name of the header that should be checked for a delay period (in milliseconds) or a Date to delay until. If this property is set, any such header value will take precedence over this handler's default delay.

setDelayExpression

public void setDelayExpression(org.springframework.expression.Expression delayExpression)

Specify the Expression that should be checked for a delay period (in milliseconds) or a Date to delay until. If this property is set, the result of the expression evaluation will take precedence over this handler's default delay.

setIgnoreExpressionFailures

public void setIgnoreExpressionFailures(boolean ignoreExpressionFailures)

Specify whether Exceptions thrown by delayExpression evaluation should be ignored (only logged). In this case case the delayer will fall back to the to the defaultDelay. If this property is specified as false, any delayExpression evaluation Exception will be thrown to the caller without falling back to the to the defaultDelay. Default is true.

See Also:

determineDelayForMessage(org.springframework.integration.Message<?>)

setMessageStore

public void setMessageStore(MessageGroupStore messageStore)

Specify the MessageGroupStore that should be used to store Messages while awaiting the delay.

setDelayedAdviceChain

public void setDelayedAdviceChain(java.util.List<org.aopalliance.aop.Advice> delayedAdviceChain)

Specify the List<Advice> to advise DelayHandler.ReleaseMessageHandler proxy. Usually used to add transactions to delayed messages retrieved from a transactional message store.

See Also:

createReleaseMessageTask()

getComponentType

public java.lang.String getComponentType()

Description copied from class: IntegrationObjectSupport

Subclasses may implement this method to provide component type information.

Specified by:

getComponentType in interface NamedComponent

Overrides:

getComponentType in class AbstractMessageHandler

doInit

protected void doInit()

Overrides:

doInit in class AbstractReplyProducingMessageHandler

handleRequestMessage

protected java.lang.Object handleRequestMessage(Message<?> requestMessage)

Checks if 'requestMessage' wasn't delayed before (releaseMessageAfterDelay(org.springframework.integration.Message<?>, long) and DelayHandler.DelayedMessageWrapper). Than determine 'delay' for 'requestMessage' (determineDelayForMessage(org.springframework.integration.Message<?>)) and if delay > 0 schedules 'releaseMessage' task after 'delay'.

Specified by:

handleRequestMessage in class AbstractReplyProducingMessageHandler

Parameters:

requestMessage - - the Message which may be delayed.

Returns:

- null if 'requestMessage' is delayed, otherwise - 'payload' from 'requestMessage'.

See Also:

releaseMessage(org.springframework.integration.Message<?>)

getDelayedMessageCount

public int getDelayedMessageCount()

Specified by:

getDelayedMessageCount in interface DelayHandlerManagement

reschedulePersistedMessages

public void reschedulePersistedMessages()

Used for reading persisted Messages in the 'messageStore' to reschedule them e.g. upon application restart. The logic is based on iteration over messageGroup.getMessages() and schedules task about 'delay' logic. This behavior is dictated by the avoidance of invocation thread overload.

Specified by:

reschedulePersistedMessages in interface DelayHandlerManagement

onApplicationEvent

public void onApplicationEvent(org.springframework.context.event.ContextRefreshedEvent event)

Handles ContextRefreshedEvent to invoke reschedulePersistedMessages() as late as possible after application context startup. Also it checks initialized to ignore other ContextRefreshedEvents which may be published in the 'parent-child' contexts, e.g. in the Spring-MVC applications.

Specified by:

onApplicationEvent in interface org.springframework.context.ApplicationListener<org.springframework.context.event.ContextRefreshedEvent>

Parameters:

event - - ContextRefreshedEvent which occurs after Application context is completely initialized.

See Also:

reschedulePersistedMessages()