docs/user-manual/modules/ROOT/pages/content-enricher.adoc - camel - Git at Google

 [[ContentEnricher-ContentEnricher]]
 = Content Enricher

 Camel supports the
 http://www.enterpriseintegrationpatterns.com/DataEnricher.html[Content
 Enricher] from the xref:enterprise-integration-patterns.adoc[EIP
 patterns] using a xref:message-translator.adoc[Message Translator], an
 arbitrary xref:processor.adoc[Processor] in the routing logic, or using
 the xref:content-enricher.adoc[enrich] DSL element to enrich the
 message.

 image::eip/DataEnricher.gif[image]

 [[ContentEnricher-ContentenrichmentusingaMessageTranslatororaProcessor]]
 == Content enrichment using a Message Translator or a Processor

 *Using the* *xref:fluent-builders.adoc[Fluent Builders]*

 You can use xref:templating.adoc[Templating] to consume a message from
 one destination, transform it with something like
 xref:components::velocity-component.adoc[Velocity] or xref:components::xquery-component.adoc[XQuery], and then send
 it on to another destination. For example using InOnly (one way
 messaging)

 [source,java]
 ----
 from("activemq:My.Queue")
     .to("velocity:com/acme/MyResponse.vm")
     .to("activemq:Another.Queue");
 ----

 If you want to use InOut (request-reply) semantics to process requests
 on the *My.Queue* queue on xref:components::activemq-component.adoc[ActiveMQ] with a template
 generated response, then sending responses back to the JMSReplyTo
 Destination you could use this:

 [source,java]
 ----
 from("activemq:My.Queue")
     .to("velocity:com/acme/MyResponse.vm");
 ----

 Here is a simple example using the xref:dsl.adoc[DSL] directly to
 transform the message

 [source,java]
 ----
 include::{examplesdir}/core/camel-core/src/test/java/org/apache/camel/processor/TransformViaDSLTest.java[tags=example]
 ----

 In this example we add our own xref:processor.adoc[Processor] using
 explicit Java

 [source,java]
 ----
 include::{examplesdir}/core/camel-core/src/test/java/org/apache/camel/processor/TransformTest.java[tags=example]
 ----

 we can use xref:bean-integration.adoc[Bean Integration] to use any Java
 method on any bean to act as the transformer

 [source,java]
 ----
 from("activemq:My.Queue")
     .beanRef("myBeanName", "myMethodName")
     .to("activemq:Another.Queue");
 ----

 For further examples of this pattern in use you could look at one of the
 JUnit tests

 * https://github.com/apache/camel/blob/master/core/camel-core/src/test/java/org/apache/camel/processor/TransformTest.java[TransformTest]
 * https://github.com/apache/camel/blob/master/core/camel-core/src/test/java/org/apache/camel/processor/TransformViaDSLTest.java[TransformViaDSLTest]

 *Using Spring XML*

 [source,xml]
 ----
 <route>
     <from uri="activemq:Input"/>
     <bean ref="myBeanName" method="doTransform"/>
     <to uri="activemq:Output"/>
 </route>
 ----

 [[ContentEnricher-ContentenrichmentusingtheenrichDSLelement]]
 == Content enrichment using the `enrich` DSL element

 Camel comes with two flavors of content enricher in the DSL

 * `enrich`
 * `pollEnrich`

 `enrich` uses a `Producer` to obtain the additional data. It is usually
 used for xref:requestReply-eip.adoc[Request Reply] messaging, for instance
 to invoke an external web service. +
 `pollEnrich` on the other hand uses a xref:polling-consumer.adoc[Polling
 Consumer] to obtain the additional data. It is usually used for
 xref:event-message.adoc[Event Message] messaging, for instance to read a
 file or download a xref:components::ftp-component.adoc[FTP] file.

 Camel 2.15 or older - Data from current Exchange not used

 `pollEnrich` or `enrich` does *not* access any data from the current
 xref:exchange.adoc[Exchange] which means when polling it cannot use any
 of the existing headers you may have set on the
 xref:exchange.adoc[Exchange]. For example you cannot set a filename in
 the `Exchange.FILE_NAME` header and use `pollEnrich` to consume only
 that file. For that you *must* set the filename in the endpoint URI.

 Instead of using `enrich` you can use xref:recipientList-eip.adoc[Recipient
 List] and have dynamic endpoints and define an `AggregationStrategy` on
 the xref:recipientList-eip.adoc[Recipient List] which then would work as a
 `enrich` would do.

 pollEnrich only accept one message as response. That means that if you
 target to enrich your original message with the enricher collecting
 messages from a seda, ... components using an aggregation strategy. Only
 one response message will be aggregated with the original message.

 From *Camel 2.16* onwards both enrich and pollEnrich supports dynamic
 endpoints that uses an xref:expression.adoc[Expression] to compute the
 uri, which allows to use data from the current
 xref:exchange.adoc[Exchange]. In other words all what is told above no
 longer apply and it just works.

 [[ContentEnricher-EnrichOptions]]
 == Enrich Options

 confluenceTableSmall

 [width="100%",cols="34%,33%,33%",options="header",]
 |=======================================================================
 |Name |Default Value |Description
 |`uri` |  |The endpoint uri for the external service to enrich from. You
 must use either `uri` or `ref`. *Important:* From Camel 2.16 onwards,
 this option is removed, and you use an xref:expression.adoc[Expression]
 to configure the uri, such as xref:simple-language.adoc[Simple] or
 xref:constant-language.adoc[Constant] or any other dynamic language that can
 compute the uri dynamically using values from the current
 xref:exchange.adoc[Exchange].

 |`ref` |  |Refers to the endpoint for the external service to enrich
 from. You must use either `uri` or `ref`.  **Important:** From Camel
 2.16 onwards, this option is removed, and you use an
 xref:expression.adoc[Expression] to configure the uri, such as
 xref:simple-language.adoc[Simple] or xref:constant-language.adoc[Constant] or any other
 dynamic language that can compute the uri dynamically using values from
 the current  xref:exchange.adoc[Exchange].

 |expression |  |*Camel 2.16:* Mandatory.
 The xref:expression.adoc[Expression] to configure the uri, such as
 xref:simple-language.adoc[Simple] or xref:constant-language.adoc[Constant] or any other
 dynamic language that can compute the uri dynamically using values from
 the current  xref:exchange.adoc[Exchange].

 |`strategyRef` |  |Refers to an
 https://github.com/apache/camel/blob/master/core/camel-api/src/main/java/org/apache/camel/AggregationStrategy.java[AggregationStrategy]
 to be used to merge the reply from the external service, into a single
 outgoing message. By default Camel will use the reply from the external
 service as outgoing message. From *Camel 2.12* onwards you can also use
 a POJO as the `AggregationStrategy`, see the
 xref:aggregate-eip.adoc[Aggregate] page for more 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 the xref:aggregate-eip.adoc[Aggregate] page for
 more details.

 |`strategyMethodAllowNull` |`false` |*Camel 2.12:* If this option is
 `false` then the aggregate method is not used if there was no data to
 enrich. If this option is `true` then `null` values is used as the
 `oldExchange` (when no data to enrich), when using POJOs as the
 `AggregationStrategy`. See the xref:aggregate-eip.adoc[Aggregate] page for
 more details.

 |`aggregateOnException` |`false` |*Camel 2.14:* If this option is
 `false` then the aggregate method is *not* used if there was an
 exception thrown while trying to retrieve the data to enrich from the
 resource. Setting this option to `true` allows end users to control what
 to do if there was an exception in the `aggregate` method. For example
 to suppress the exception or set a custom message body etc.

 |`shareUnitOfWork` |`false` |*Camel 2.16:*  Shares the unit of work with
 the parent and the resource exchange. Enrich will by default not share
 unit of work between the parent exchange and the resource exchange. This
 means the resource exchange has its own individual unit of work. See
 xref:split-eip.adoc[Splitter] for more information and example.

 |`cacheSize` |  |*Camel 2.16:* Allows to configure the cache size for
 the `ProducerCache` which caches producers for reuse in the enrich. Will
 by default use the default cache size which is 1000. Setting the value
 to -1 allows to turn off the cache all together.

 |`ignoreInvalidEndpoint` |`false` |**Camel 2.16:** Whether to ignore an
 endpoint URI that could not be resolved. If disabled, Camel will throw
 an exception identifying the invalid endpoint URI.
 |=======================================================================

 *Using the* *xref:fluent-builders.adoc[Fluent Builders]*


 [source,java]
 ----
 AggregationStrategy aggregationStrategy = ...

 from("direct:start")
     .enrich("direct:resource", aggregationStrategy)
     .to("direct:result");

 from("direct:resource") ...
 ----

 The content enricher (`enrich`) retrieves additional data from a
 _resource endpoint_ in order to enrich an incoming message (contained in
 the _original exchange_). An aggregation strategy is used to combine the
 original exchange and the _resource exchange_. The first parameter of
 the `AggregationStrategy.aggregate(Exchange, Exchange)` method
 corresponds to the the original exchange, the second parameter the
 resource exchange. The results from the resource endpoint are stored in
 the resource exchange's out-message. Here's an example template for
 implementing an aggregation strategy:

 [source,java]
 ----
 public class ExampleAggregationStrategy implements AggregationStrategy {

     public Exchange aggregate(Exchange original, Exchange resource) {
         Object originalBody = original.getIn().getBody();
         Object resourceResponse = resource.getIn().getBody();
         Object mergeResult = ... // combine original body and resource response

         if (original.getPattern().isOutCapable()) {
             original.getOut().setBody(mergeResult);
         } else {
             original.getIn().setBody(mergeResult);
         }

         return original;
     }
 }
 ----

 Using this template the original exchange can be of any pattern. The
 resource exchange created by the enricher is always an in-out exchange.

 *Using Spring XML*

 The same example in the Spring DSL

 [source,xml]
 ----
 <camelContext id="camel" xmlns="http://camel.apache.org/schema/spring">
     <route>
         <from uri="direct:start"/>
         <enrich strategyRef="aggregationStrategy">
             <constant>direct:resource</constant>
         </enrich>
         <to uri="direct:result"/>
     </route>
     <route>
         <from uri="direct:resource"/>
         ...
     </route>
 </camelContext>

 <bean id="aggregationStrategy" class="..." />
 ----

 [[ContentEnricher-Aggregationstrategyisoptional]]
 === Aggregation strategy is optional

 The aggregation strategy is optional. If you do not provide it Camel
 will by default just use the body obtained from the resource.

 [source,java]
 ----
 from("direct:start")
     .enrich("direct:resource")
     .to("direct:result");
 ----

 In the route above the message sent to the `direct:result` endpoint will
 contain the output from the `direct:resource` as we do not use any
 custom aggregation.

 And for Spring DSL:

 [source,xml]
 ----
 <route>
     <from uri="direct:start"/>
     <enrich>
         <constant>direct:resource</constant>
     </enrich>
     <to uri="direct:result"/>
 </route>
 ----

 [[ContentEnricher-Usingdynamicuris]]
 === Using dynamic uris

 *Since Camel 2.16*

 From Camel 2.16 onwards enrich and pollEnrich supports using dynamic
 uris computed based on information from the
 current xref:exchange.adoc[Exchange]. For example to enrich from
 a xref:components::http-component.adoc[HTTP] endpoint where the header with key orderId is
 used as part of the content-path of the HTTP url:

 [source,java]
 ----
 from("direct:start")
     .enrich().simple("http:myserver/$\{header.orderId}/order")
     .to("direct:result");
 ----

 And in XML DSL

 [source,xml]
 ----
 <route>
     <from uri="direct:start"/>
     <enrich>
         <simple>http:myserver/$\{header.orderId}/order</simple>
     </enrich>
     <to uri="direct:result"/>
 </route>
 ----

 [[ContentEnricher-ContentenrichmentusingpollEnrich]]
 === Content enrichment using `pollEnrich`

 The `pollEnrich` works just as the `enrich` however as it uses a
 xref:polling-consumer.adoc[Polling Consumer] we have 3 methods when
 polling

 * receive
 * receiveNoWait
 * receive(timeout)

 [[ContentEnricher-PollEnrichOptions]]
 === PollEnrich Options

 [width="100%",cols="34%,33%,33%",options="header",]
 |=======================================================================
 |Name |Default Value |Description
 |`uri` |  |The endpoint uri for the external service to enrich from. You
 must use either `uri` or `ref`. **Important:** From Camel 2.16 onwards,
 this option is removed, and you use an xref:expression.adoc[Expression]
 to configure the uri, such as xref:simple-language.adoc[Simple] or
 xref:constant-language.adoc[Constant] or any other dynamic language that can
 compute the uri dynamically using values from the current
  xref:exchange.adoc[Exchange].

 |`ref` |  |Refers to the endpoint for the external service to enrich
 from. You must use either `uri` or `ref`. **Important:** From Camel 2.16
 onwards, this option is removed, and you use an
 xref:expression.adoc[Expression] to configure the uri, such as
 xref:simple-language.adoc[Simple] or xref:constant-language.adoc[Constant] or any other
 dynamic language that can compute the uri dynamically using values from
 the current  xref:exchange.adoc[Exchange].

 |`expression` |  |**Camel 2.16:** Mandatory.
 The xref:expression.adoc[Expression] to configure the uri, such as
 xref:simple-language.adoc[Simple] or xref:constant-language.adoc[Constant] or any other
 dynamic language that can compute the uri dynamically using values from
 the current xref:exchange.adoc[Exchange].

 |`strategyRef` |  |Refers to an
 https://github.com/apache/camel/blob/master/core/camel-api/src/main/java/org/apache/camel/AggregationStrategy.java[AggregationStrategy]
 to be used to merge the reply from the external service, into a single
 outgoing message. By default Camel will use the reply from the external
 service as outgoing message. From *Camel 2.12* onwards you can also use
 a POJO as the `AggregationStrategy`, see the
 xref:aggregate-eip.adoc[Aggregate] page for more 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 the xref:aggregate-eip.adoc[Aggregate] page for
 more details.

 |`strategyMethodAllowNull` |`false` |*Camel 2.12:* If this option is
 `false` then the aggregate method is not used if there was no data to
 enrich. If this option is `true` then `null` values is used as the
 `oldExchange` (when no data to enrich), when using POJOs as the
 `AggregationStrategy`. See the xref:aggregate-eip.adoc[Aggregate] page for
 more details.

 |`timeout` |`-1` |Timeout in millis when polling from the external
 service. See below for important details about the timeout.

 |`aggregateOnException` |`false` |*Camel 2.14:* If this option is
 `false` then the aggregate method is *not* used if there was an
 exception thrown while trying to retrieve the data to enrich from the
 resource. Setting this option to `true` allows end users to control what
 to do if there was an exception in the `aggregate` method. For example
 to suppress the exception or set a custom message body etc.

 |`cacheSize` |  |*Camel 2.16:* Allows to configure the cache size for
 the `ConsumerCache` which caches consumers for reuse in the pollEnrich.
 Will by default use the default cache size which is 1000. Setting the
 value to -1 allows to turn off the cache all together.

 |`ignoreInvalidEndpoint` |`false` |**Camel 2.16:** Whether to ignore an
 endpoint URI that could not be resolved. If disabled, Camel will throw
 an exception identifying the invalid endpoint URI.
 |=======================================================================

 Good practice to use timeout value

 By default Camel will use the `receive`. Which may block until there is
 a message available. It is therefore recommended to always provide a
 timeout value, to make this clear that we may wait for a message, until
 the timeout is hit.

 If there is no data then the `newExchange` in the aggregation strategy
 is `null`.

 You can pass in a timeout value that determines which method to use

 * if timeout is -1 or other negative number then `receive` is selected
 (*Important:* the `receive` method may block if there is no message)
 * if timeout is 0 then `receiveNoWait` is selected
 * otherwise `receive(timeout)` is selected

 The timeout values is in millis.

 Camel 2.15 or older - Data from current Exchange not used

 `pollEnrich` does *not* access any data from the current
 xref:exchange.adoc[Exchange] which means when polling it cannot use any
 of the existing headers you may have set on the
 xref:exchange.adoc[Exchange]. For example you cannot set a filename in
 the `Exchange.FILE_NAME` header and use `pollEnrich` to consume only
 that file. For that you *must* set the filename in the endpoint URI.

 From **Camel 2.16** onwards both enrich and pollEnrich supports dynamic
 endpoints that uses an xref:expression.adoc[Expression] to compute the
 uri, which allows to use data from the current
 xref:exchange.adoc[Exchange]. In other words all what is told above no
 longer apply and it just works.

 [[ContentEnricher-Example]]
 ==== Example

 In this example we enrich the message by loading the content from the
 file named inbox/data.txt.

 [source,java]
 ----
 from("direct:start")
     .pollEnrich("file:inbox?fileName=data.txt")
     .to("direct:result");
 ----

 And in XML DSL you do:

 [source,xml]
 ----
 <route>
     <from uri="direct:start"/>
     <pollEnrich>
         <constant>file:inbox?fileName=data.txt</constant>
     </pollEnrich>
     <to uri="direct:result"/>
 </route>
 ----

 If there is no file then the message is empty. We can use a timeout to
 either wait (potentially forever) until a file exists, or use a timeout
 to wait a certain period.

 For example to wait up to 5 seconds you can do:

 [source,xml]
 ----
 <route>
     <from uri="direct:start"/>
     <pollEnrich timeout="5000">
         <constant>file:inbox?fileName=data.txt</constant>
     </pollEnrich>
     <to uri="direct:result"/>
 </route>
 ----

 [[ContentEnricher-Usingdynamicuris.1]]
 ==== Using dynamic uris

 *Since Camel 2.16*

 From Camel 2.16 onwards enrich and pollEnrich supports using dynamic
 uris computed based on information from the
 current xref:exchange.adoc[Exchange]. For example to pollEnrich from an
 endpoint that uses a header to indicate a xref:components::seda-component.adoc[SEDA] queue
 name:

 [source,java]
 ----
 from("direct:start")
     .pollEnrich()
     .simple("seda:$\{header.name}")
     .to("direct:result");
 ----

 And in XML DSL

 [source,xml]
 ----
 <route>
     <from uri="direct:start"/>
     <pollEnrich>
         <simple>seda:$\{header.name}</simple>
     </pollEnrich>
     <to uri="direct:result"/>
 </route>
 ----
	[[ContentEnricher-ContentEnricher]]
	= Content Enricher

	Camel supports the
	http://www.enterpriseintegrationpatterns.com/DataEnricher.html[Content
	Enricher] from the xref:enterprise-integration-patterns.adoc[EIP
	patterns] using a xref:message-translator.adoc[Message Translator], an
	arbitrary xref:processor.adoc[Processor] in the routing logic, or using
	the xref:content-enricher.adoc[enrich] DSL element to enrich the
	message.

	image::eip/DataEnricher.gif[image]

	[[ContentEnricher-ContentenrichmentusingaMessageTranslatororaProcessor]]
	== Content enrichment using a Message Translator or a Processor

	Using the xref:fluent-builders.adoc[Fluent Builders]

	You can use xref:templating.adoc[Templating] to consume a message from
	one destination, transform it with something like
	xref:components::velocity-component.adoc[Velocity] or xref:components::xquery-component.adoc[XQuery], and then send
	it on to another destination. For example using InOnly (one way
	messaging)

	[source,java]
	----
	from("activemq:My.Queue")
	.to("velocity:com/acme/MyResponse.vm")
	.to("activemq:Another.Queue");
	----

	If you want to use InOut (request-reply) semantics to process requests
	on the My.Queue queue on xref:components::activemq-component.adoc[ActiveMQ] with a template
	generated response, then sending responses back to the JMSReplyTo
	Destination you could use this:

	[source,java]
	----
	from("activemq:My.Queue")
	.to("velocity:com/acme/MyResponse.vm");
	----

	Here is a simple example using the xref:dsl.adoc[DSL] directly to
	transform the message

	[source,java]
	----
	include::{examplesdir}/core/camel-core/src/test/java/org/apache/camel/processor/TransformViaDSLTest.java[tags=example]
	----

	In this example we add our own xref:processor.adoc[Processor] using
	explicit Java

	[source,java]
	----
	include::{examplesdir}/core/camel-core/src/test/java/org/apache/camel/processor/TransformTest.java[tags=example]
	----

	we can use xref:bean-integration.adoc[Bean Integration] to use any Java
	method on any bean to act as the transformer

	[source,java]
	----
	from("activemq:My.Queue")
	.beanRef("myBeanName", "myMethodName")
	.to("activemq:Another.Queue");
	----

	For further examples of this pattern in use you could look at one of the
	JUnit tests

	* https://github.com/apache/camel/blob/master/core/camel-core/src/test/java/org/apache/camel/processor/TransformTest.java[TransformTest]
	* https://github.com/apache/camel/blob/master/core/camel-core/src/test/java/org/apache/camel/processor/TransformViaDSLTest.java[TransformViaDSLTest]

	Using Spring XML

	[source,xml]
	----
	<route>
	<from uri="activemq:Input"/>
	<bean ref="myBeanName" method="doTransform"/>
	<to uri="activemq:Output"/>
	</route>
	----

	[[ContentEnricher-ContentenrichmentusingtheenrichDSLelement]]
	== Content enrichment using the `enrich` DSL element

	Camel comes with two flavors of content enricher in the DSL

	* `enrich`
	* `pollEnrich`

	`enrich` uses a `Producer` to obtain the additional data. It is usually
	used for xref:requestReply-eip.adoc[Request Reply] messaging, for instance
	to invoke an external web service. +
	`pollEnrich` on the other hand uses a xref:polling-consumer.adoc[Polling
	Consumer] to obtain the additional data. It is usually used for
	xref:event-message.adoc[Event Message] messaging, for instance to read a
	file or download a xref:components::ftp-component.adoc[FTP] file.

	Camel 2.15 or older - Data from current Exchange not used

	`pollEnrich` or `enrich` does not access any data from the current
	xref:exchange.adoc[Exchange] which means when polling it cannot use any
	of the existing headers you may have set on the
	xref:exchange.adoc[Exchange]. For example you cannot set a filename in
	the `Exchange.FILE_NAME` header and use `pollEnrich` to consume only
	that file. For that you must set the filename in the endpoint URI.

	Instead of using `enrich` you can use xref:recipientList-eip.adoc[Recipient
	List] and have dynamic endpoints and define an `AggregationStrategy` on
	the xref:recipientList-eip.adoc[Recipient List] which then would work as a
	`enrich` would do.

	pollEnrich only accept one message as response. That means that if you
	target to enrich your original message with the enricher collecting
	messages from a seda, ... components using an aggregation strategy. Only
	one response message will be aggregated with the original message.

	From Camel 2.16 onwards both enrich and pollEnrich supports dynamic
	endpoints that uses an xref:expression.adoc[Expression] to compute the
	uri, which allows to use data from the current
	xref:exchange.adoc[Exchange]. In other words all what is told above no
	longer apply and it just works.

	[[ContentEnricher-EnrichOptions]]
	== Enrich Options

	confluenceTableSmall

	[width="100%",cols="34%,33%,33%",options="header",]
	\|=======================================================================
	\|Name \|Default Value \|Description
	\|`uri` \| \|The endpoint uri for the external service to enrich from. You
	must use either `uri` or `ref`. Important: From Camel 2.16 onwards,
	this option is removed, and you use an xref:expression.adoc[Expression]
	to configure the uri, such as xref:simple-language.adoc[Simple] or
	xref:constant-language.adoc[Constant] or any other dynamic language that can
	compute the uri dynamically using values from the current
	xref:exchange.adoc[Exchange].

	\|`ref` \| \|Refers to the endpoint for the external service to enrich
	from. You must use either `uri` or `ref`. Important: From Camel
	2.16 onwards, this option is removed, and you use an
	xref:expression.adoc[Expression] to configure the uri, such as
	xref:simple-language.adoc[Simple] or xref:constant-language.adoc[Constant] or any other
	dynamic language that can compute the uri dynamically using values from
	the current xref:exchange.adoc[Exchange].

	\|expression \| \|Camel 2.16: Mandatory.
	The xref:expression.adoc[Expression] to configure the uri, such as
	xref:simple-language.adoc[Simple] or xref:constant-language.adoc[Constant] or any other
	dynamic language that can compute the uri dynamically using values from
	the current xref:exchange.adoc[Exchange].

	\|`strategyRef` \| \|Refers to an
	https://github.com/apache/camel/blob/master/core/camel-api/src/main/java/org/apache/camel/AggregationStrategy.java[AggregationStrategy]
	to be used to merge the reply from the external service, into a single
	outgoing message. By default Camel will use the reply from the external
	service as outgoing message. From Camel 2.12 onwards you can also use
	a POJO as the `AggregationStrategy`, see the
	xref:aggregate-eip.adoc[Aggregate] page for more 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 the xref:aggregate-eip.adoc[Aggregate] page for
	more details.

	\|`strategyMethodAllowNull` \|`false` \|Camel 2.12: If this option is
	`false` then the aggregate method is not used if there was no data to
	enrich. If this option is `true` then `null` values is used as the
	`oldExchange` (when no data to enrich), when using POJOs as the
	`AggregationStrategy`. See the xref:aggregate-eip.adoc[Aggregate] page for
	more details.

	\|`aggregateOnException` \|`false` \|Camel 2.14: If this option is
	`false` then the aggregate method is not used if there was an
	exception thrown while trying to retrieve the data to enrich from the
	resource. Setting this option to `true` allows end users to control what
	to do if there was an exception in the `aggregate` method. For example
	to suppress the exception or set a custom message body etc.

	\|`shareUnitOfWork` \|`false` \|Camel 2.16: Shares the unit of work with
	the parent and the resource exchange. Enrich will by default not share
	unit of work between the parent exchange and the resource exchange. This
	means the resource exchange has its own individual unit of work. See
	xref:split-eip.adoc[Splitter] for more information and example.

	\|`cacheSize` \| \|Camel 2.16: Allows to configure the cache size for
	the `ProducerCache` which caches producers for reuse in the enrich. Will
	by default use the default cache size which is 1000. Setting the value
	to -1 allows to turn off the cache all together.

	\|`ignoreInvalidEndpoint` \|`false` \|Camel 2.16: Whether to ignore an
	endpoint URI that could not be resolved. If disabled, Camel will throw
	an exception identifying the invalid endpoint URI.
	\|=======================================================================

	Using the xref:fluent-builders.adoc[Fluent Builders]


	[source,java]
	----
	AggregationStrategy aggregationStrategy = ...

	from("direct:start")
	.enrich("direct:resource", aggregationStrategy)
	.to("direct:result");

	from("direct:resource") ...
	----

	The content enricher (`enrich`) retrieves additional data from a
	_resource endpoint_ in order to enrich an incoming message (contained in
	the _original exchange_). An aggregation strategy is used to combine the
	original exchange and the _resource exchange_. The first parameter of
	the `AggregationStrategy.aggregate(Exchange, Exchange)` method
	corresponds to the the original exchange, the second parameter the
	resource exchange. The results from the resource endpoint are stored in
	the resource exchange's out-message. Here's an example template for
	implementing an aggregation strategy:

	[source,java]
	----
	public class ExampleAggregationStrategy implements AggregationStrategy {

	public Exchange aggregate(Exchange original, Exchange resource) {
	Object originalBody = original.getIn().getBody();
	Object resourceResponse = resource.getIn().getBody();
	Object mergeResult = ... // combine original body and resource response

	if (original.getPattern().isOutCapable()) {
	original.getOut().setBody(mergeResult);
	} else {
	original.getIn().setBody(mergeResult);
	}

	return original;
	}
	}
	----

	Using this template the original exchange can be of any pattern. The
	resource exchange created by the enricher is always an in-out exchange.

	Using Spring XML

	The same example in the Spring DSL

	[source,xml]
	----
	<camelContext id="camel" xmlns="http://camel.apache.org/schema/spring">
	<route>
	<from uri="direct:start"/>
	<enrich strategyRef="aggregationStrategy">
	<constant>direct:resource</constant>
	</enrich>
	<to uri="direct:result"/>
	</route>
	<route>
	<from uri="direct:resource"/>
	...
	</route>
	</camelContext>

	<bean id="aggregationStrategy" class="..." />
	----

	[[ContentEnricher-Aggregationstrategyisoptional]]
	=== Aggregation strategy is optional

	The aggregation strategy is optional. If you do not provide it Camel
	will by default just use the body obtained from the resource.

	[source,java]
	----
	from("direct:start")
	.enrich("direct:resource")
	.to("direct:result");
	----

	In the route above the message sent to the `direct:result` endpoint will
	contain the output from the `direct:resource` as we do not use any
	custom aggregation.

	And for Spring DSL:

	[source,xml]
	----
	<route>
	<from uri="direct:start"/>
	<enrich>
	<constant>direct:resource</constant>
	</enrich>
	<to uri="direct:result"/>
	</route>
	----

	[[ContentEnricher-Usingdynamicuris]]
	=== Using dynamic uris

	Since Camel 2.16

	From Camel 2.16 onwards enrich and pollEnrich supports using dynamic
	uris computed based on information from the
	current xref:exchange.adoc[Exchange]. For example to enrich from
	a xref:components::http-component.adoc[HTTP] endpoint where the header with key orderId is
	used as part of the content-path of the HTTP url:

	[source,java]
	----
	from("direct:start")
	.enrich().simple("http:myserver/$\{header.orderId}/order")
	.to("direct:result");
	----

	And in XML DSL

	[source,xml]
	----
	<route>
	<from uri="direct:start"/>
	<enrich>
	<simple>http:myserver/$\{header.orderId}/order</simple>
	</enrich>
	<to uri="direct:result"/>
	</route>
	----

	[[ContentEnricher-ContentenrichmentusingpollEnrich]]
	=== Content enrichment using `pollEnrich`

	The `pollEnrich` works just as the `enrich` however as it uses a
	xref:polling-consumer.adoc[Polling Consumer] we have 3 methods when
	polling

	* receive
	* receiveNoWait
	* receive(timeout)

	[[ContentEnricher-PollEnrichOptions]]
	=== PollEnrich Options

	[width="100%",cols="34%,33%,33%",options="header",]
	\|=======================================================================
	\|Name \|Default Value \|Description
	\|`uri` \| \|The endpoint uri for the external service to enrich from. You
	must use either `uri` or `ref`. Important: From Camel 2.16 onwards,
	this option is removed, and you use an xref:expression.adoc[Expression]
	to configure the uri, such as xref:simple-language.adoc[Simple] or
	xref:constant-language.adoc[Constant] or any other dynamic language that can
	compute the uri dynamically using values from the current
	xref:exchange.adoc[Exchange].

	\|`ref` \| \|Refers to the endpoint for the external service to enrich
	from. You must use either `uri` or `ref`. Important: From Camel 2.16
	onwards, this option is removed, and you use an
	xref:expression.adoc[Expression] to configure the uri, such as
	xref:simple-language.adoc[Simple] or xref:constant-language.adoc[Constant] or any other
	dynamic language that can compute the uri dynamically using values from
	the current xref:exchange.adoc[Exchange].

	\|`expression` \| \|Camel 2.16: Mandatory.
	The xref:expression.adoc[Expression] to configure the uri, such as
	xref:simple-language.adoc[Simple] or xref:constant-language.adoc[Constant] or any other
	dynamic language that can compute the uri dynamically using values from
	the current xref:exchange.adoc[Exchange].

	\|`strategyRef` \| \|Refers to an
	https://github.com/apache/camel/blob/master/core/camel-api/src/main/java/org/apache/camel/AggregationStrategy.java[AggregationStrategy]
	to be used to merge the reply from the external service, into a single
	outgoing message. By default Camel will use the reply from the external
	service as outgoing message. From Camel 2.12 onwards you can also use
	a POJO as the `AggregationStrategy`, see the
	xref:aggregate-eip.adoc[Aggregate] page for more 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 the xref:aggregate-eip.adoc[Aggregate] page for
	more details.

	\|`strategyMethodAllowNull` \|`false` \|Camel 2.12: If this option is
	`false` then the aggregate method is not used if there was no data to
	enrich. If this option is `true` then `null` values is used as the
	`oldExchange` (when no data to enrich), when using POJOs as the
	`AggregationStrategy`. See the xref:aggregate-eip.adoc[Aggregate] page for
	more details.

	\|`timeout` \|`-1` \|Timeout in millis when polling from the external
	service. See below for important details about the timeout.

	\|`aggregateOnException` \|`false` \|Camel 2.14: If this option is
	`false` then the aggregate method is not used if there was an
	exception thrown while trying to retrieve the data to enrich from the
	resource. Setting this option to `true` allows end users to control what
	to do if there was an exception in the `aggregate` method. For example
	to suppress the exception or set a custom message body etc.

	\|`cacheSize` \| \|Camel 2.16: Allows to configure the cache size for
	the `ConsumerCache` which caches consumers for reuse in the pollEnrich.
	Will by default use the default cache size which is 1000. Setting the
	value to -1 allows to turn off the cache all together.

	\|`ignoreInvalidEndpoint` \|`false` \|Camel 2.16: Whether to ignore an
	endpoint URI that could not be resolved. If disabled, Camel will throw
	an exception identifying the invalid endpoint URI.
	\|=======================================================================

	Good practice to use timeout value

	By default Camel will use the `receive`. Which may block until there is
	a message available. It is therefore recommended to always provide a
	timeout value, to make this clear that we may wait for a message, until
	the timeout is hit.

	If there is no data then the `newExchange` in the aggregation strategy
	is `null`.

	You can pass in a timeout value that determines which method to use

	* if timeout is -1 or other negative number then `receive` is selected
	(Important: the `receive` method may block if there is no message)
	* if timeout is 0 then `receiveNoWait` is selected
	* otherwise `receive(timeout)` is selected

	The timeout values is in millis.

	Camel 2.15 or older - Data from current Exchange not used

	`pollEnrich` does not access any data from the current
	xref:exchange.adoc[Exchange] which means when polling it cannot use any
	of the existing headers you may have set on the
	xref:exchange.adoc[Exchange]. For example you cannot set a filename in
	the `Exchange.FILE_NAME` header and use `pollEnrich` to consume only
	that file. For that you must set the filename in the endpoint URI.

	From Camel 2.16 onwards both enrich and pollEnrich supports dynamic
	endpoints that uses an xref:expression.adoc[Expression] to compute the
	uri, which allows to use data from the current
	xref:exchange.adoc[Exchange]. In other words all what is told above no
	longer apply and it just works.

	[[ContentEnricher-Example]]
	==== Example

	In this example we enrich the message by loading the content from the
	file named inbox/data.txt.

	[source,java]
	----
	from("direct:start")
	.pollEnrich("file:inbox?fileName=data.txt")
	.to("direct:result");
	----

	And in XML DSL you do:

	[source,xml]
	----
	<route>
	<from uri="direct:start"/>
	<pollEnrich>
	<constant>file:inbox?fileName=data.txt</constant>
	</pollEnrich>
	<to uri="direct:result"/>
	</route>
	----

	If there is no file then the message is empty. We can use a timeout to
	either wait (potentially forever) until a file exists, or use a timeout
	to wait a certain period.

	For example to wait up to 5 seconds you can do:

	[source,xml]
	----
	<route>
	<from uri="direct:start"/>
	<pollEnrich timeout="5000">
	<constant>file:inbox?fileName=data.txt</constant>
	</pollEnrich>
	<to uri="direct:result"/>
	</route>
	----

	[[ContentEnricher-Usingdynamicuris.1]]
	==== Using dynamic uris

	Since Camel 2.16

	From Camel 2.16 onwards enrich and pollEnrich supports using dynamic
	uris computed based on information from the
	current xref:exchange.adoc[Exchange]. For example to pollEnrich from an
	endpoint that uses a header to indicate a xref:components::seda-component.adoc[SEDA] queue
	name:

	[source,java]
	----
	from("direct:start")
	.pollEnrich()
	.simple("seda:$\{header.name}")
	.to("direct:result");
	----

	And in XML DSL

	[source,xml]
	----
	<route>
	<from uri="direct:start"/>
	<pollEnrich>
	<simple>seda:$\{header.name}</simple>
	</pollEnrich>
	<to uri="direct:result"/>
	</route>
	----