Idempotent Consumer

The Idempotent Consumer from the EIP patterns is used to filter out duplicate messages.

The Idempotent Consumer essentially acts like a Message Filter to filter out duplicates.

Camel will add the message id eagerly to the repository to detect duplication also for Exchange's' currently in progress. On completion Camel will remove the message id from the repository if the Exchange failed, otherwise it stays there.

Options

The Idempotent Consumer eip supports 5 options, which are listed below.

Name	Description	Default	Type
expression	Required Expression used to calculate the correlation key to use for duplicate check. The Exchange which has the same correlation key is regarded as a duplicate and will be rejected.		ExpressionDefinition
idempotentRepository	Sets the reference name of the message id repository.		IdempotentRepository
eager	Sets whether to eagerly add the key to the idempotent repository or wait until the exchange is complete. Eager is default enabled.	true	Boolean
completionEager	Sets whether to complete the idempotent consumer eager or when the exchange is done. If this option is true to complete eager, then the idempotent consumer will trigger its completion when the exchange reached the end of the block of the idempotent consumer pattern. So if the exchange is continued routed after the block ends, then whatever happens there does not affect the state. If this option is false (default) to not complete eager, then the idempotent consumer will complete when the exchange is done being routed. So if the exchange is continued routed after the block ends, then whatever happens there also affect the state. For example if the exchange failed due to an exception, then the state of the idempotent consumer will be a rollback.	false	Boolean
skipDuplicate	Sets whether to skip duplicates or not. The default behavior is to skip duplicates. A duplicate message would have the Exchange property org.apache.camel.Exchange#DUPLICATE_MESSAGE set to a Boolean#TRUE value. A none duplicate message will not have this property set.	true	Boolean
removeOnFailure	Sets whether to remove or keep the key on failure. The default behavior is to remove the key on failure.	true	Boolean
description	Sets the description of this node.		DescriptionDefinition

Name

Description

Default

Type

expression

Required Expression used to calculate the correlation key to use for duplicate check. The Exchange which has the same correlation key is regarded as a duplicate and will be rejected.

ExpressionDefinition

idempotentRepository

Sets the reference name of the message id repository.

IdempotentRepository

eager

Sets whether to eagerly add the key to the idempotent repository or wait until the exchange is complete. Eager is default enabled.

true

Boolean

completionEager

Sets whether to complete the idempotent consumer eager or when the exchange is done. If this option is true to complete eager, then the idempotent consumer will trigger its completion when the exchange reached the end of the block of the idempotent consumer pattern. So if the exchange is continued routed after the block ends, then whatever happens there does not affect the state. If this option is false (default) to not complete eager, then the idempotent consumer will complete when the exchange is done being routed. So if the exchange is continued routed after the block ends, then whatever happens there also affect the state. For example if the exchange failed due to an exception, then the state of the idempotent consumer will be a rollback.

false

Boolean

skipDuplicate

Sets whether to skip duplicates or not. The default behavior is to skip duplicates. A duplicate message would have the Exchange property org.apache.camel.Exchange#DUPLICATE_MESSAGE set to a Boolean#TRUE value. A none duplicate message will not have this property set.

true

Boolean

removeOnFailure

Sets whether to remove or keep the key on failure. The default behavior is to remove the key on failure.

true

Boolean

description

Sets the description of this node.

DescriptionDefinition

Idempotent Consumer implementations

The idempotent consumer provides a pluggable repository which you can implement your own org.apache.camel.spi.IdempotentRepository.

Camel provides the following Idempotent Consumer implementations:

Example

For example see the above implementations for more details.