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Posted to commits@camel.apache.org by bu...@apache.org on 2015/08/12 17:20:12 UTC
svn commit: r961632 [3/4] - in /websites/production/camel/content:
aggregator2.html book-in-one-page.html book-pattern-appendix.html
cache/main.pageCache camel-2160-release.html
Modified: websites/production/camel/content/book-pattern-appendix.html
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--- websites/production/camel/content/book-pattern-appendix.html (original)
+++ websites/production/camel/content/book-pattern-appendix.html Wed Aug 12 15:20:12 2015
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</div></div><div class="confluence-information-macro confluence-information-macro-information"><p class="title">Implementation of shared unit of work</p><span class="aui-icon aui-icon-small aui-iconfont-info confluence-information-macro-icon"></span><div class="confluence-information-macro-body"><p>So in reality the unit of work is not shared as a single object instance. Instead <code>SubUnitOfWork</code> is attached to their parent, and issues callback to the parent about their status (commit or rollback). This may be refactored in Camel 3.0 where larger API changes can be done.</p></div></div><p></p><h4 id="BookPatternAppendix-UsingThisPattern.18">Using This Pattern</h4>
<p>If you would like to use this EIP Pattern then please read the <a shape="rect" href="getting-started.html">Getting Started</a>, you may also find the <a shape="rect" href="architecture.html">Architecture</a> useful particularly the description of <a shape="rect" href="endpoint.html">Endpoint</a> and <a shape="rect" href="uris.html">URIs</a>. Then you could try out some of the <a shape="rect" href="examples.html">Examples</a> first before trying this pattern out.</p>
-<h3 id="BookPatternAppendix-Aggregator">Aggregator</h3><p><strong>This applies for Camel version 2.3 or newer. If you use an older version then use this <a shape="rect" href="aggregator.html">Aggregator</a> link instead.</strong></p><p>The <a shape="rect" class="external-link" href="http://www.enterpriseintegrationpatterns.com/Aggregator.html" rel="nofollow">Aggregator</a> from the <a shape="rect" href="enterprise-integration-patterns.html">EIP patterns</a> allows you to combine a number of messages together into a single message.</p><p><span class="confluence-embedded-file-wrapper"><img class="confluence-embedded-image confluence-external-resource" src="http://www.enterpriseintegrationpatterns.com/img/Aggregator.gif" data-image-src="http://www.enterpriseintegrationpatterns.com/img/Aggregator.gif"></span></p><p>A correlation <a shape="rect" href="expression.html">Expression</a> is used to determine the messages which should be aggregated together. If you want to aggregate all messag
es into a single message, just use a constant expression. An AggregationStrategy is used to combine all the message exchanges for a single correlation key into a single message exchange.</p><h3 id="BookPatternAppendix-Aggregatoroptions">Aggregator options</h3><p>The aggregator supports the following options:</p><div class="confluenceTableSmall"><div class="table-wrap"><table class="confluenceTable"><tbody><tr><th colspan="1" rowspan="1" class="confluenceTh"><p>Option</p></th><th colspan="1" rowspan="1" class="confluenceTh"><p>Default</p></th><th colspan="1" rowspan="1" class="confluenceTh"><p>Description</p></th></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>correlationExpression</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Mandatory <a shape="rect" href="expression.html">Expression</a> which evaluates the correlation key to use for aggregation. The <a shape="rect" href="exchange.html">Ex
change</a> 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 <code>ignoreBadCorrelationKeys</code> option.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>aggregationStrategy</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Mandatory <code>AggregationStrategy</code> which is used to <em>merge</em> the incoming <a shape="rect" href="exchange.html">Exchange</a> with the existing already merged exchanges. At first call the <code>oldExchange</code> parameter is <code>null</code>. On subsequent invocations the <code>oldExchange</code> contains the merged exchanges and <code>newExchange</code> is of course the new incoming Exchange. From <strong>Camel 2.9.2</strong> onwards the strategy can also be a <code>TimeoutAwareAggregationStrategy</code> implementation, supporting the timeo
ut callback, see further below for more details. From <strong>Camel 2.16</strong> onwards the strategy can also be a <code>PreCompletionAwareAggregationStrategy</code> implementation which then runs the completion check in pre-completion mode. See further below for more details.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>strategyRef</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>A reference to lookup the <code>AggregationStrategy</code> in the <a shape="rect" href="registry.html">Registry</a>. From <strong>Camel 2.12</strong> onwards you can also use a POJO as the <code>AggregationStrategy</code>, see further below for details.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>strategyMethodName</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>Camel 2.12:</strong> This option
can be used to explicit declare the method name to use, when using POJOs as the <code>AggregationStrategy</code>. See further below for more details.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>strategyMethodAllowNull</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>Camel 2.12:</strong> If this option is <code>false</code> then the aggregate method is not used for the very first aggregation. If this option is <code>true</code> then <code>null</code> values is used as the <code>oldExchange</code> (at the very first aggregation), when using POJOs as the <code>AggregationStrategy</code>. See further below for more details.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>completionSize</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Number of messages aggregated befo
re the aggregation is complete. This option can be set as either a fixed value or using an <a shape="rect" href="expression.html">Expression</a> which allows you to evaluate a size dynamically - will use <code>Integer</code> as result. If both are set Camel will fallback to use the fixed value if the <a shape="rect" href="expression.html">Expression</a> result was <code>null</code> or <code>0</code>.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>completionTimeout</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>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 <a shape="rect" href="expression.html">Expression</a> which allows you to evaluate a timeout dynamically - will use <code>Long</code> as result. If both are set Camel will fallback to use the fixed value if the <a shape="rect" href="expr
ession.html">Expression</a> result was <code>null</code> or <code>0</code>. You cannot use this option together with completionInterval, only one of the two can be used.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>completionInterval</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>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.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>completionPredicate</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>A <a shape="rect" href="predicate.html">Predicate</a> to indicate when an aggregated exchange is complete. Starting in <strong>Camel 2.15</stron
g>, if this is not specified and the AggregationStrategy object implements Predicate, the aggregationStrategy object will be used as the completionPredicate.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>completionFromBatchConsumer</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>This option is if the exchanges are coming from a <a shape="rect" href="batch-consumer.html">Batch Consumer</a>. Then when enabled the <a shape="rect" href="aggregator2.html">Aggregator2</a> will use the batch size determined by the <a shape="rect" href="batch-consumer.html">Batch Consumer</a> in the message header <code>CamelBatchSize</code>. See more details at <a shape="rect" href="batch-consumer.html">Batch Consumer</a>. This can be used to aggregate all files consumed from a <a shape="rect" href="file2.html">File</a> endpoint in that given poll.</p></td></tr><tr><td colspan="1" rowspan="1" c
lass="confluenceTd"><p>forceCompletionOnStop</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>Camel 2.9</strong> Indicates to complete all current aggregated exchanges when the context is stopped</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>eagerCheckCompletion</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Whether or not to eager check for completion when a new incoming <a shape="rect" href="exchange.html">Exchange</a> has been received. This option influences the behavior of the <code>completionPredicate</code> option as the <a shape="rect" href="exchange.html">Exchange</a> being passed in changes accordingly. When <code>false</code> the <a shape="rect" href="exchange.html">Exchange</a> passed in the <a shape="rect" href="predicate.html">Predicate</a> is the <em>aggregat
ed</em> Exchange which means any information you may store on the aggregated Exchange from the <code>AggregationStrategy</code> is available for the <a shape="rect" href="predicate.html">Predicate</a>. When <code>true</code> the <a shape="rect" href="exchange.html">Exchange</a> passed in the <a shape="rect" href="predicate.html">Predicate</a> is the <em>incoming</em> <a shape="rect" href="exchange.html">Exchange</a>, which means you can access data from the incoming Exchange.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>groupExchanges</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>If enabled then Camel will group all aggregated Exchanges into a single combined <code>org.apache.camel.impl.GroupedExchange</code> 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 incomi
ng Exchanges into a single output Exchange without coding a custom <code>AggregationStrategy</code> yourself. <strong>Important:</strong> This option does <strong>not</strong> support persistent repository with the aggregator. See further below for an example and more details.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>ignoreInvalidCorrelationKeys</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>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.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>closeCorrelationKeyOnCompletion</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Whether or not too <em>late</em> 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 <code>closedCorrelationKeyException</code> exception. When using this option you pass in a <code>integer</code> 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.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>discardOnCompletionTimeout</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>Camel 2.5:</strong> Whether or not exchanges which complete due to a timeout should be discarded. If enabled then when a timeout occurs the aggregated message will <strong>not</strong>
be sent out but dropped (discarded).</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>aggregationRepository</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Allows you to plugin you own implementation of <code>org.apache.camel.spi.AggregationRepository</code> which keeps track of the current inflight aggregated exchanges. Camel uses by default a memory based implementation.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>aggregationRepositoryRef</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Reference to lookup a <code>aggregationRepository</code> in the <a shape="rect" href="registry.html">Registry</a>.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>parallelProcessing</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td colspa
n="1" rowspan="1" class="confluenceTd"><p>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.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>executorService</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>If using <code>parallelProcessing</code> you can specify a custom thread pool to be used. In fact also if you are not using <code>parallelProcessing</code> this custom thread pool is used to send out aggregated exchanges as well.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>executorServiceRef</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Reference to
lookup a <code>executorService</code> in the <a shape="rect" href="registry.html">Registry</a></p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>timeoutCheckerExecutorService</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>Camel 2.9:</strong> If using either of the <code>completionTimeout</code>, <code>completionTimeoutExpression</code>, or <code>completionInterval</code> 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.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>timeoutCheckerExecutorServiceRef</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>Camel 2.9:</strong> Reference to lookup a <code>timeoutCheckerExecutorServ
ice</code> in the <a shape="rect" href="registry.html">Registry</a></p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>optimisticLocking</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>Camel 2.11:</strong> Turns on using optimistic locking, which requires the <code>aggregationRepository</code> being used, is supporting this by implementing the <code>org.apache.camel.spi.OptimisticLockingAggregationRepository</code> interface.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>optimisticLockRetryPolicy</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>Camel 2.11.1:</strong> Allows to configure retry settings when using optimistic locking.</p></td></tr></tbody></table></div></div><h3 id="BookPatternAppendix-ExchangeProperties">Exchange Properties</h3><p>The following p
roperties are set on each aggregated Exchange:</p><div class="confluenceTableSmall"><div class="table-wrap"><table class="confluenceTable"><tbody><tr><th colspan="1" rowspan="1" class="confluenceTh"><p>header</p></th><th colspan="1" rowspan="1" class="confluenceTh"><p>type</p></th><th colspan="1" rowspan="1" class="confluenceTh"><p>description</p></th></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>CamelAggregatedSize</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>int</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>The total number of Exchanges aggregated into this combined Exchange.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>CamelAggregatedCompletedBy</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>String</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Indicator how the aggregation was completed as a value of either: <code>predicate</code>, <code>size</code>, <code>stra
tegy</code>, <code>consumer</code>, <code>timeout</code>, <code>forceCompletion</code> or <code>interval</code>.</p></td></tr></tbody></table></div></div><h3 id="BookPatternAppendix-AboutAggregationStrategy">About AggregationStrategy</h3><p>The <code>AggregationStrategy</code> is used for aggregating the old (lookup by its correlation id) and the new exchanges together into a single exchange. Possible implementations include performing some kind of combining or delta processing, such as adding line items together into an invoice or just using the newest exchange and removing old exchanges such as for state tracking or market data prices; where old values are of little use.</p><p>Notice the aggregation strategy is a mandatory option and must be provided to the aggregator.</p><p>Here are a few example AggregationStrategy implementations that should help you create your own custom strategy.</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent p
dl">
+<h3 id="BookPatternAppendix-Aggregator">Aggregator</h3><p><strong>This applies for Camel version 2.3 or newer. If you use an older version then use this <a shape="rect" href="aggregator.html">Aggregator</a> link instead.</strong></p><p>The <a shape="rect" class="external-link" href="http://www.enterpriseintegrationpatterns.com/Aggregator.html" rel="nofollow">Aggregator</a> from the <a shape="rect" href="enterprise-integration-patterns.html">EIP patterns</a> allows you to combine a number of messages together into a single message.</p><p><span class="confluence-embedded-file-wrapper"><img class="confluence-embedded-image confluence-external-resource" src="http://www.enterpriseintegrationpatterns.com/img/Aggregator.gif" data-image-src="http://www.enterpriseintegrationpatterns.com/img/Aggregator.gif"></span></p><p>A correlation <a shape="rect" href="expression.html">Expression</a> is used to determine the messages which should be aggregated together. If you want to aggregate all messag
es into a single message, just use a constant expression. An AggregationStrategy is used to combine all the message exchanges for a single correlation key into a single message exchange.</p><h3 id="BookPatternAppendix-Aggregatoroptions">Aggregator options</h3><p>The aggregator supports the following options:</p><div class="confluenceTableSmall"><div class="table-wrap"><table class="confluenceTable"><tbody><tr><th colspan="1" rowspan="1" class="confluenceTh"><p>Option</p></th><th colspan="1" rowspan="1" class="confluenceTh"><p>Default</p></th><th colspan="1" rowspan="1" class="confluenceTh"><p>Description</p></th></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>correlationExpression</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Mandatory <a shape="rect" href="expression.html">Expression</a> which evaluates the correlation key to use for aggregation. The <a shape="rect" href="exchange.html">Ex
change</a> 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 <code>ignoreBadCorrelationKeys</code> option.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>aggregationStrategy</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Mandatory <code>AggregationStrategy</code> which is used to <em>merge</em> the incoming <a shape="rect" href="exchange.html">Exchange</a> with the existing already merged exchanges. At first call the <code>oldExchange</code> parameter is <code>null</code>. On subsequent invocations the <code>oldExchange</code> contains the merged exchanges and <code>newExchange</code> is of course the new incoming Exchange. From <strong>Camel 2.9.2</strong> onwards the strategy can also be a <code>TimeoutAwareAggregationStrategy</code> implementation, supporting the timeo
ut callback, see further below for more details. From <strong>Camel 2.16</strong> onwards the strategy can also be a <code>PreCompletionAwareAggregationStrategy</code> implementation which then runs the completion check in pre-completion mode. See further below for more details.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>strategyRef</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>A reference to lookup the <code>AggregationStrategy</code> in the <a shape="rect" href="registry.html">Registry</a>. From <strong>Camel 2.12</strong> onwards you can also use a POJO as the <code>AggregationStrategy</code>, see further below for details.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>strategyMethodName</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>Camel 2.12:</strong> This option
can be used to explicit declare the method name to use, when using POJOs as the <code>AggregationStrategy</code>. See further below for more details.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>strategyMethodAllowNull</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>Camel 2.12:</strong> If this option is <code>false</code> then the aggregate method is not used for the very first aggregation. If this option is <code>true</code> then <code>null</code> values is used as the <code>oldExchange</code> (at the very first aggregation), when using POJOs as the <code>AggregationStrategy</code>. See further below for more details.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>completionSize</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Number of messages aggregated befo
re the aggregation is complete. This option can be set as either a fixed value or using an <a shape="rect" href="expression.html">Expression</a> which allows you to evaluate a size dynamically - will use <code>Integer</code> as result. If both are set Camel will fallback to use the fixed value if the <a shape="rect" href="expression.html">Expression</a> result was <code>null</code> or <code>0</code>.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>completionTimeout</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>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 <a shape="rect" href="expression.html">Expression</a> which allows you to evaluate a timeout dynamically - will use <code>Long</code> as result. If both are set Camel will fallback to use the fixed value if the <a shape="rect" href="expr
ession.html">Expression</a> result was <code>null</code> or <code>0</code>. You cannot use this option together with completionInterval, only one of the two can be used.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>completionInterval</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>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.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>completionPredicate</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>A <a shape="rect" href="predicate.html">Predicate</a> to indicate when an aggregated exchange is complete. Starting in <strong>Camel 2.15</stron
g>, if this is not specified and the AggregationStrategy object implements Predicate, the aggregationStrategy object will be used as the completionPredicate.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>completionFromBatchConsumer</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>This option is if the exchanges are coming from a <a shape="rect" href="batch-consumer.html">Batch Consumer</a>. Then when enabled the <a shape="rect" href="aggregator2.html">Aggregator2</a> will use the batch size determined by the <a shape="rect" href="batch-consumer.html">Batch Consumer</a> in the message header <code>CamelBatchSize</code>. See more details at <a shape="rect" href="batch-consumer.html">Batch Consumer</a>. This can be used to aggregate all files consumed from a <a shape="rect" href="file2.html">File</a> endpoint in that given poll.</p></td></tr><tr><td colspan="1" rowspan="1" c
lass="confluenceTd"><p>forceCompletionOnStop</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>Camel 2.9</strong> Indicates to complete all current aggregated exchanges when the context is stopped</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd">completeAllOnStop</td><td colspan="1" rowspan="1" class="confluenceTd"><code>false</code></td><td colspan="1" rowspan="1" class="confluenceTd"><strong>Camel 2.16:</strong> Indicates to wait to complete all current and partial (pending) aggregated exchanges when the context is stopped. This also means that we will wait for all pending exchanges which are stored in the aggregation repository to complete so the repository is empty before we can stop.  You may want to enable this when using the memory based aggregation repository that is memory based only, and do not store data on disk. When this option is en
abled, then the aggregator is waiting to complete all those exchanges before its stopped, when stopping CamelContext or the route using it.</td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>eagerCheckCompletion</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Whether or not to eager check for completion when a new incoming <a shape="rect" href="exchange.html">Exchange</a> has been received. This option influences the behavior of the <code>completionPredicate</code> option as the <a shape="rect" href="exchange.html">Exchange</a> being passed in changes accordingly. When <code>false</code> the <a shape="rect" href="exchange.html">Exchange</a> passed in the <a shape="rect" href="predicate.html">Predicate</a> is the <em>aggregated</em> Exchange which means any information you may store on the aggregated Exchange from the <code>AggregationStrategy</code> is available for the <a s
hape="rect" href="predicate.html">Predicate</a>. When <code>true</code> the <a shape="rect" href="exchange.html">Exchange</a> passed in the <a shape="rect" href="predicate.html">Predicate</a> is the <em>incoming</em> <a shape="rect" href="exchange.html">Exchange</a>, which means you can access data from the incoming Exchange.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>groupExchanges</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>If enabled then Camel will group all aggregated Exchanges into a single combined <code>org.apache.camel.impl.GroupedExchange</code> 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 <code>AggregationStrategy</code> yourself. <strong>Important:</strong> This option doe
s <strong>not</strong> support persistent repository with the aggregator. See further below for an example and more details.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>ignoreInvalidCorrelationKeys</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>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.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>closeCorrelationKeyOnCompletion</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Whether or not too <em>late</em> 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 denie
d. Camel will then throw a <code>closedCorrelationKeyException</code> exception. When using this option you pass in a <code>integer</code> 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.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>discardOnCompletionTimeout</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>Camel 2.5:</strong> Whether or not exchanges which complete due to a timeout should be discarded. If enabled then when a timeout occurs the aggregated message will <strong>not</strong> be sent out but dropped (discarded).</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>aggregationRepository</p></td><td colspan="1"
rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Allows you to plugin you own implementation of <code>org.apache.camel.spi.AggregationRepository</code> which keeps track of the current inflight aggregated exchanges. Camel uses by default a memory based implementation.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>aggregationRepositoryRef</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Reference to lookup a <code>aggregationRepository</code> in the <a shape="rect" href="registry.html">Registry</a>.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>parallelProcessing</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>When aggregated are completed they are being send out of the aggregator. This option indicates whether or not C
amel 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.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>executorService</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>If using <code>parallelProcessing</code> you can specify a custom thread pool to be used. In fact also if you are not using <code>parallelProcessing</code> this custom thread pool is used to send out aggregated exchanges as well.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>executorServiceRef</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Reference to lookup a <code>executorService</code> in the <a shape="rect" href="registry.html">Registry</a></p></td></tr><tr><td colspan="1" rowspan="1" class="confl
uenceTd"><p>timeoutCheckerExecutorService</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>Camel 2.9:</strong> If using either of the <code>completionTimeout</code>, <code>completionTimeoutExpression</code>, or <code>completionInterval</code> 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.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>timeoutCheckerExecutorServiceRef</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>Camel 2.9:</strong> Reference to lookup a <code>timeoutCheckerExecutorService</code> in the <a shape="rect" href="registry.html">Registry</a></p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>optimisticLockin
g</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><code>false</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>Camel 2.11:</strong> Turns on using optimistic locking, which requires the <code>aggregationRepository</code> being used, is supporting this by implementing the <code>org.apache.camel.spi.OptimisticLockingAggregationRepository</code> interface.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p>optimisticLockRetryPolicy</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p> </p></td><td colspan="1" rowspan="1" class="confluenceTd"><p><strong>Camel 2.11.1:</strong> Allows to configure retry settings when using optimistic locking.</p></td></tr></tbody></table></div></div><h3 id="BookPatternAppendix-ExchangeProperties">Exchange Properties</h3><p>The following properties are set on each aggregated Exchange:</p><div class="confluenceTableSmall"><div class="table-wrap"><table class="confluenceTable"><tbody><tr><th
colspan="1" rowspan="1" class="confluenceTh"><p>header</p></th><th colspan="1" rowspan="1" class="confluenceTh"><p>type</p></th><th colspan="1" rowspan="1" class="confluenceTh"><p>description</p></th></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>CamelAggregatedSize</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>int</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>The total number of Exchanges aggregated into this combined Exchange.</p></td></tr><tr><td colspan="1" rowspan="1" class="confluenceTd"><p><code>CamelAggregatedCompletedBy</code></p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>String</p></td><td colspan="1" rowspan="1" class="confluenceTd"><p>Indicator how the aggregation was completed as a value of either: <code>predicate</code>, <code>size</code>, <code>strategy</code>, <code>consumer</code>, <code>timeout</code>, <code>forceCompletion</code> or <code>interval</code>.</p></td></tr></tbody></table></div></div
><h3 id="BookPatternAppendix-AboutAggregationStrategy">About AggregationStrategy</h3><p>The <code>AggregationStrategy</code> is used for aggregating the old (lookup by its correlation id) and the new exchanges together into a single exchange. Possible implementations include performing some kind of combining or delta processing, such as adding line items together into an invoice or just using the newest exchange and removing old exchanges such as for state tracking or market data prices; where old values are of little use.</p><p>Notice the aggregation strategy is a mandatory option and must be provided to the aggregator.</p><p>Here are a few example AggregationStrategy implementations that should help you create your own custom strategy.</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<script class="brush: java; gutter: false; theme: Default" type="syntaxhighlighter"><![CDATA[//simply combines Exchange String body values using '+' as a delimiter
class StringAggregationStrategy implements AggregationStrategy {
@@ -1707,7 +1707,7 @@ from("direct:start")
.aggregate(header("id"), new BodyInAggregatingStrategy()).completionTimeout(3000)
.to("mock:aggregated");
]]></script>
-</div></div><p>And the same example using Spring XML:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
+</div></div>And the same example using Spring XML:<div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<script class="brush: xml; gutter: false; theme: Default" type="syntaxhighlighter"><![CDATA[
<camelContext xmlns="http://camel.apache.org/schema/spring">
<route>
@@ -1733,7 +1733,7 @@ from("direct:start")
.aggregate(header("id"), new BodyInAggregatingStrategy()).completionSize(3)
.to("mock:aggregated");
]]></script>
-</div></div><p>And the same example using Spring XML:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
+</div></div>And the same example using Spring XML:<div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<script class="brush: xml; gutter: false; theme: Default" type="syntaxhighlighter"><![CDATA[
<camelContext xmlns="http://camel.apache.org/schema/spring">
<route>
@@ -1759,7 +1759,7 @@ from("direct:start")
.aggregate(header("id"), new BodyInAggregatingStrategy()).completionPredicate(body().contains("A+B+C"))
.to("mock:aggregated");
]]></script>
-</div></div><p>And the same example using Spring XML:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
+</div></div>And the same example using Spring XML:<div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<script class="brush: xml; gutter: false; theme: Default" type="syntaxhighlighter"><![CDATA[
<camelContext xmlns="http://camel.apache.org/schema/spring">
<route>
@@ -1778,7 +1778,7 @@ from("direct:start")
<bean id="aggregatorStrategy" class="org.apache.camel.processor.BodyInAggregatingStrategy"/>
]]></script>
-</div></div><p>And the other situation where we use the <code>eagerCheckCompletion</code> option to tell Camel to use the incoming Exchange. Notice how we can just test in the completion predicate that the incoming message is the <em>END</em> message:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
+</div></div>And the other situation where we use the <code>eagerCheckCompletion</code> option to tell Camel to use the incoming Exchange. Notice how we can just test in the completion predicate that the incoming message is the <em>END</em> message:<div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<script class="brush: java; gutter: false; theme: Default" type="syntaxhighlighter"><![CDATA[
from("direct:start")
// aggregate all exchanges correlated by the id header.
@@ -1790,7 +1790,7 @@ from("direct:start")
.eagerCheckCompletion().completionPredicate(body().isEqualTo("END"))
.to("mock:aggregated");
]]></script>
-</div></div><p>And the same example using Spring XML:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
+</div></div>And the same example using Spring XML:<div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<script class="brush: xml; gutter: false; theme: Default" type="syntaxhighlighter"><![CDATA[
<camelContext xmlns="http://camel.apache.org/schema/spring">
<route>
@@ -1819,7 +1819,7 @@ from("direct:start")
.aggregate(header("id"), new BodyInAggregatingStrategy()).completionTimeout(header("timeout"))
.to("mock:aggregated");
]]></script>
-</div></div><p>And the same example using Spring XML:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
+</div></div>And the same example using Spring XML:<div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<script class="brush: xml; gutter: false; theme: Default" type="syntaxhighlighter"><![CDATA[
<camelContext xmlns="http://camel.apache.org/schema/spring">
<route>
@@ -1838,7 +1838,7 @@ from("direct:start")
<bean id="aggregatorStrategy" class="org.apache.camel.processor.BodyInAggregatingStrategy"/>
]]></script>
-</div></div><p><strong>Note:</strong> You can also add a fixed timeout value and Camel will fallback to use this value if the dynamic value was <code>null</code> or <code>0</code>.</p><h4 id="BookPatternAppendix-UsingdynamiccompletionSize">Using dynamic completionSize</h4><p>In this example we want to aggregate all incoming messages based on a dynamic size per correlation key. The size is computed at runtime based on the <code>mySize</code> header in the incoming messages. This is done using the <code>completionSize</code> option as shown:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
+</div></div><strong>Note:</strong> You can also add a fixed timeout value and Camel will fallback to use this value if the dynamic value was <code>null</code> or <code>0</code>.<h4 id="BookPatternAppendix-UsingdynamiccompletionSize">Using dynamic completionSize</h4><p>In this example we want to aggregate all incoming messages based on a dynamic size per correlation key. The size is computed at runtime based on the <code>mySize</code> header in the incoming messages. This is done using the <code>completionSize</code> option as shown:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<script class="brush: java; gutter: false; theme: Default" type="syntaxhighlighter"><![CDATA[
from("direct:start")
// aggregate all exchanges correlated by the id header.
@@ -1848,7 +1848,7 @@ from("direct:start")
.aggregate(header("id"), new BodyInAggregatingStrategy()).completionSize(header("mySize"))
.to("mock:aggregated");
]]></script>
-</div></div><p>And the same example using Spring XML:</p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
+</div></div>And the same example using Spring XML:<div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<script class="brush: xml; gutter: false; theme: Default" type="syntaxhighlighter"><![CDATA[
<camelContext xmlns="http://camel.apache.org/schema/spring">
<route>
@@ -1867,7 +1867,7 @@ from("direct:start")
<bean id="aggregatorStrategy" class="org.apache.camel.processor.BodyInAggregatingStrategy"/>
]]></script>
-</div></div><p><strong>Note:</strong> You can also add a fixed size value and Camel will fallback to use this value if the dynamic value was <code>null</code> or <code>0</code>.</p><p></p><h4 id="BookPatternAppendix-UsingThisPattern.19">Using This Pattern</h4>
+</div></div><strong>Note:</strong> You can also add a fixed size value and Camel will fallback to use this value if the dynamic value was <code>null</code> or <code>0</code>.<p></p><h4 id="BookPatternAppendix-UsingThisPattern.19">Using This Pattern</h4>
<p>If you would like to use this EIP Pattern then please read the <a shape="rect" href="getting-started.html">Getting Started</a>, you may also find the <a shape="rect" href="architecture.html">Architecture</a> useful particularly the description of <a shape="rect" href="endpoint.html">Endpoint</a> and <a shape="rect" href="uris.html">URIs</a>. Then you could try out some of the <a shape="rect" href="examples.html">Examples</a> first before trying this pattern out.</p><h4 id="BookPatternAppendix-CompletingcurrentgroupdecidedfromtheAggregationStrategy">Completing current group decided from the AggregationStrategy</h4><p><strong>Available as of Camel 2.15</strong></p><p>The <code>AggregationStrategy</code> can now included a property on the returned <code>Exchange</code> that contains a boolean to indicate if the current group should be completed. This allows to overrule any existing completion predicates / sizes / timeouts etc, and complete the group.</p><p>For example the
following logic (from an unit test) will complete the group if the message body size is larger than 5. This is done by setting the property <span style="line-height: 1.4285715;">Exchange.AGGREGATION_COMPLETE_CURRENT_GROUP to true.</span></p><div class="code panel pdl" style="border-width: 1px;"><div class="codeContent panelContent pdl">
<script class="brush: java; gutter: false; theme: Default" type="syntaxhighlighter"><![CDATA[ public final class MyCompletionStrategy implements AggregationStrategy {
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