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The aggregator supports the following options:

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{div:class=confluenceTableSmall} || Option || Default || Description || | correlationExpression | | Mandatory [Expression] which evaluates the correlation key to use for aggregation. The [Exchange] which has the same correlation key is aggregated together. If the correlation key could not be evaluated an Exception is thrown. You can disable this by using the {{ignoreBadCorrelationKeys}} option. | | aggregationStrategy | | Mandatory {{AggregationStrategy}} which is used to _merge_ the incoming [Exchange] with the existing already merged exchanges. At first call the {{oldExchange}} parameter is {{null}}. On subsequent invocations the {{oldExchange}} contains the merged exchanges and {{newExchange}} is of course the new incoming Exchange. From *Camel 2.9.2* onwards the strategy can also be a {{TimeoutAwareAggregationStrategy}} implementation, supporting the timeout callback, see further below for more details. | | strategyRef | | A reference to lookup the {{AggregationStrategy}} in the [Registry]. From *Camel 2.12* onwards you can also use a POJO as the {{AggregationStrategy}}, see further below for details. | | strategyMethodName | | *Camel 2.12:* This option can be used to explicit declare the method name to use, when using POJOs as the {{AggregationStrategy}}. See further below for more details. | | strategyMethodAllowNull | {{false}} | *Camel 2.12:* If this option is {{false}} then the aggregate method is not used for the very first aggregation. If this option is {{true}} then {{null}} values is used as the {{oldExchange}} (at the very first aggregation), when using POJOs as the {{AggregationStrategy}}. See further below for more details. | | completionSize | | Number of messages aggregated before the aggregation is complete. This option can be set as either a fixed value or using an [Expression] which allows you to evaluate a size dynamically - will use {{Integer}} as result. If both are set Camel will fallback to use the fixed value if the [Expression] result was {{null}} or {{0}}. | | completionTimeout | | Time in millis that an aggregated exchange should be inactive before its complete. This option can be set as either a fixed value or using an [Expression] which allows you to evaluate a timeout dynamically - will use {{Long}} as result. If both are set Camel will fallback to use the fixed value if the [Expression] result was {{null}} or {{0}}. You cannot use this option together with completionInterval, only one of the two can be used. | | completionInterval | | A repeating period in millis by which the aggregator will complete all current aggregated exchanges. Camel has a background task which is triggered every period. You cannot use this option together with completionTimeout, only one of them can be used. | | completionPredicate | | A [Predicate] to indicate when an aggregated exchange is complete. | | completionFromBatchConsumer | {{false}} | This option is if the exchanges are coming from a [Batch Consumer]. Then when enabled the [Aggregator2] will use the batch size determined by the [Batch Consumer] in the message header {{CamelBatchSize}}. See more details at [Batch Consumer]. This can be used to aggregate all files consumed from a [File|File2] endpoint in that given poll. | | forceCompletionOnStop | {{false}} | *Camel 2.9* Indicates to complete all current aggregated exchanges when the context is stopped | | eagerCheckCompletion | {{false}} | Whether or not to eager check for completion when a new incoming [Exchange] has been received. This option influences the behavior of the {{completionPredicate}} option as the [Exchange] being passed in changes accordingly. When {{false}} the [Exchange] passed in the [Predicate] is the _aggregated_ Exchange which means any information you may store on the aggregated Exchange from the {{AggregationStrategy}} is available for the [Predicate]. When {{true}} the [Exchange] passed in the [Predicate] is the _incoming_ [Exchange], which means you can access data from the incoming Exchange. | | groupExchanges | {{false}} | If enabled then Camel will group all aggregated Exchanges into a single combined {{

Option

Default

Description

correlationExpression

 

Mandatory Expression which evaluates the correlation key to use for aggregation. The Exchange which has the same correlation key is aggregated together. If the correlation key could not be evaluated an Exception is thrown. You can disable this by using the ignoreBadCorrelationKeys option.

aggregationStrategy

 

Mandatory AggregationStrategy which is used to merge the incoming Exchange with the existing already merged exchanges. At first call the oldExchange parameter is null. On subsequent invocations the oldExchange contains the merged exchanges and newExchange is of course the new incoming Exchange. From Camel 2.9.2 onwards the strategy can also be a TimeoutAwareAggregationStrategy implementation, supporting the timeout callback, see further below for more details.

strategyRef

 

A reference to lookup the AggregationStrategy in the Registry. From Camel 2.12 onwards you can also use a POJO as the AggregationStrategy, see further below for details.

strategyMethodName

 

Camel 2.12: This option can be used to explicit declare the method name to use, when using POJOs as the AggregationStrategy. See further below for more details.

strategyMethodAllowNull

false

Camel 2.12: If this option is false then the aggregate method is not used for the very first aggregation. If this option is true then null values is used as the oldExchange (at the very first aggregation), when using POJOs as the AggregationStrategy. See further below for more details.

completionSize

 

Number of messages aggregated before the aggregation is complete. This option can be set as either a fixed value or using an Expression which allows you to evaluate a size dynamically - will use Integer as result. If both are set Camel will fallback to use the fixed value if the Expression result was null or 0.

completionTimeout

 

Time in millis that an aggregated exchange should be inactive before its complete. This option can be set as either a fixed value or using an Expression which allows you to evaluate a timeout dynamically - will use Long as result. If both are set Camel will fallback to use the fixed value if the Expression result was null or 0. You cannot use this option together with completionInterval, only one of the two can be used.

completionInterval

 

A repeating period in millis by which the aggregator will complete all current aggregated exchanges. Camel has a background task which is triggered every period. You cannot use this option together with completionTimeout, only one of them can be used.

completionPredicate

 

A Predicate to indicate when an aggregated exchange is complete.

completionFromBatchConsumer

false

This option is if the exchanges are coming from a Batch Consumer. Then when enabled the Aggregator2 will use the batch size determined by the Batch Consumer in the message header CamelBatchSize. See more details at Batch Consumer. This can be used to aggregate all files consumed from a File endpoint in that given poll.

forceCompletionOnStop

false

Camel 2.9 Indicates to complete all current aggregated exchanges when the context is stopped

eagerCheckCompletion

false

Whether or not to eager check for completion when a new incoming Exchange has been received. This option influences the behavior of the completionPredicate option as the Exchange being passed in changes accordingly. When false the Exchange passed in the Predicate is the aggregated Exchange which means any information you may store on the aggregated Exchange from the AggregationStrategy is available for the Predicate. When true the Exchange passed in the Predicate is the incoming Exchange, which means you can access data from the incoming Exchange.

groupExchanges

false

If enabled then Camel will group all aggregated Exchanges into a single combined

org.apache.camel.impl.GroupedExchange

}}

holder

class

that

holds

all

the

aggregated

Exchanges.

And

as

a

result

only

one

Exchange

is

being

sent

out

from

the

aggregator.

Can

be

used

to

combine

many

incoming

Exchanges

into

a

single

output

Exchange

without

coding

a

custom

{{

AggregationStrategy

}}

yourself.

*

Important:

*

This

option

does

*

not

*

support

persistent

repository

with

the

aggregator.

See

further

below

for

an

example

and

more

details.

| | ignoreInvalidCorrelationKeys | {{false}} | Whether or not to ignore correlation keys which could not be evaluated to a value. By default Camel will throw an Exception, but you can enable this option and ignore the situation instead. | | closeCorrelationKeyOnCompletion | | Whether or not too _late_ Exchanges should be accepted or not. You can enable this to indicate that if a correlation key has already been completed, then any new exchanges with the same correlation key be denied. Camel will then throw a {{closedCorrelationKeyException}} exception. When using this option you pass in a {{integer}} which is a number for a LRUCache which keeps that last X number of closed correlation keys. You can pass in 0 or a negative value to indicate a unbounded cache. By passing in a number you are ensured that cache won't grow too big if you use a log of different correlation keys. | | discardOnCompletionTimeout | {{false}} | *Camel 2.5:* Whether or not exchanges which complete due to a timeout should be discarded. If enabled then when a timeout occurs the aggregated message will *not* be sent out but dropped (discarded). | | aggregationRepository | | Allows you to plugin you own implementation of {{

ignoreInvalidCorrelationKeys

false

Whether or not to ignore correlation keys which could not be evaluated to a value. By default Camel will throw an Exception, but you can enable this option and ignore the situation instead.

closeCorrelationKeyOnCompletion

 

Whether or not too late Exchanges should be accepted or not. You can enable this to indicate that if a correlation key has already been completed, then any new exchanges with the same correlation key be denied. Camel will then throw a closedCorrelationKeyException exception. When using this option you pass in a integer which is a number for a LRUCache which keeps that last X number of closed correlation keys. You can pass in 0 or a negative value to indicate a unbounded cache. By passing in a number you are ensured that cache won't grow too big if you use a log of different correlation keys.

discardOnCompletionTimeout

false

Camel 2.5: Whether or not exchanges which complete due to a timeout should be discarded. If enabled then when a timeout occurs the aggregated message will not be sent out but dropped (discarded).

aggregationRepository

 

Allows you to plugin you own implementation of org.apache.camel.spi.AggregationRepository

}}

which

keeps

track

of

the

current

inflight

aggregated

exchanges.

Camel

uses

by

default

a

memory

based

implementation.

| | aggregationRepositoryRef | | Reference to lookup a {{aggregationRepository}} in the [Registry]. | | parallelProcessing | {{false}} | When aggregated are completed they are being send out of the aggregator. This option indicates whether or not Camel should use a thread pool with multiple threads for concurrency. If no custom thread pool has been specified then Camel creates a default pool with 10 concurrent threads. | | executorService | | If using {{parallelProcessing}} you can specify a custom thread pool to be used. In fact also if you are not using {{parallelProcessing}} this custom thread pool is used to send out aggregated exchanges as well. | | executorServiceRef | | Reference to lookup a {{executorService}} in the [Registry] | | timeoutCheckerExecutorService | | *Camel 2.9:* If using either of the {{completionTimeout}}, {{completionTimeoutExpression}}, or {{completionInterval}} options a background thread is created to check for the completion for every aggregator. Set this option to provide a custom thread pool to be used rather than creating a new thread for every aggregator. | | timeoutCheckerExecutorServiceRef | | *Camel 2.9:* Reference to lookup a {{timeoutCheckerExecutorService}} in the [Registry] | | optimisticLocking | {{false}} | *Camel 2.11:* Turns on using optimistic locking, which requires the {{aggregationRepository}} being used, is supporting this by implementing the {{

aggregationRepositoryRef

 

Reference to lookup a aggregationRepository in the Registry.

parallelProcessing

false

When aggregated are completed they are being send out of the aggregator. This option indicates whether or not Camel should use a thread pool with multiple threads for concurrency. If no custom thread pool has been specified then Camel creates a default pool with 10 concurrent threads.

executorService

 

If using parallelProcessing you can specify a custom thread pool to be used. In fact also if you are not using parallelProcessing this custom thread pool is used to send out aggregated exchanges as well.

executorServiceRef

 

Reference to lookup a executorService in the Registry

timeoutCheckerExecutorService

 

Camel 2.9: If using either of the completionTimeout, completionTimeoutExpression, or completionInterval options a background thread is created to check for the completion for every aggregator. Set this option to provide a custom thread pool to be used rather than creating a new thread for every aggregator.

timeoutCheckerExecutorServiceRef

 

Camel 2.9: Reference to lookup a timeoutCheckerExecutorService in the Registry

optimisticLocking

false

Camel 2.11: Turns on using optimistic locking, which requires the aggregationRepository being used, is supporting this by implementing the org.apache.camel.spi.OptimisticLockingAggregationRepository

}}

interface.

| | optimisticLockRetryPolicy | | *Camel

optimisticLockRetryPolicy

 

Camel 2.11.1:

*

Allows

to

configure

retry

settings

when

using

optimistic

locking.

| {div}

Exchange Properties

The following properties are set on each aggregated Exchange:

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classconfluenceTableSmall

header

type

description

CamelAggregatedSize

int

The total number of Exchanges aggregated into this combined Exchange.

CamelAggregatedCompletedBy

String

Indicator how the aggregation was completed as a value of either: predicate, size, consumer, timeout, forceCompletion or interval.

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{div:class=confluenceTableSmall} || header || type || description || | {{CamelAggregatedSize}} | int | The total number of Exchanges aggregated into this combined Exchange. | | {{CamelAggregatedCompletedBy}} | String | Indicator how the aggregation was completed as a value of either: {{predicate}}, {{size}}, {{consumer}}, {{timeout}}, {{forceCompletion}} or {{interval}}. | {div}

About AggregationStrategy

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