Enrich

Camel supports the Content Enricher from the EIP patterns.

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In Camel the Content Enricher can be done in several ways:

The most natural Camel approach is using Enrich EIP, which comes as two kinds:

  • Enrich EIP: This is the most common content enricher that uses a Producer to obtain the data. It is usually used for Request Reply messaging, for instance, to invoke an external web service.

  • Poll Enrich EIP: Uses a Polling Consumer to obtain the additional data. It is usually used for Event Message messaging, for instance, to read a file or download one using FTP.

This page documents the Enrich EIP.

The Enrich eip supports 1 options, which are listed below.

Name Description Default Type

note

The note for this node.

String

description

The description for this node.

String

disabled

Whether to disable this EIP from the route during build time. Once an EIP has been disabled then it cannot be enabled later at runtime.

false

Boolean

expression

Required The expression to compute the endpoint URI to enrich from.

ExpressionDefinition

variableSend

To use a variable as the source for the message body to send. When using send variable then the message body is taken from this variable instead of the current message, however the headers from the message will still be used as well.

String

variableReceive

To use a variable to store the received message body (only body, not headers). This makes it handy to use variables for user data and to easily control what data to use for sending and receiving.

String

aggregationStrategy

Sets the 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.

AggregationStrategy

aggregationStrategyMethodName

This option can be used to explicitly declare the method name to use, when using POJOs as the AggregationStrategy.

String

aggregationStrategyMethodAllowNull

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.

String

aggregateOnException

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.

false

Boolean

shareUnitOfWork

Shares the UnitOfWork 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.

false

Boolean

cacheSize

Sets the maximum size used by the ProducerCache which is used to cache and reuse producers when uris are reused. Use 0 for default cache size, or -1 to turn cache off.

Integer

ignoreInvalidEndpoint

Whether to ignore an invalid endpoint URI when trying to create a producer with that endpoint.

false

Boolean

allowOptimisedComponents

Whether to allow components to optimise enricher if they are SendDynamicAware.

true

Boolean

autoStartComponents

Whether to auto startup components when enricher is starting up.

true

Boolean

Exchange properties

The Enrich eip supports 1 exchange properties, which are listed below.

The exchange properties are set on the Exchange by the EIP, unless otherwise specified in the description. This means those properties are available after this EIP has completed processing the Exchange.

Name Description Default Type

CamelToEndpoint

Endpoint URI where this Exchange is being sent to.

String

Content enrichment using Enrich EIP

Enrich EIP is the most common content enricher that uses a Producer to obtain the data.

The content enricher (enrich) retrieves additional data from a resource endpoint to enrich an incoming message (contained in the original exchange).

An AggregationStrategy is used to combine the original exchange and the resource exchange. The first parameter of the AggregationStrategy.aggregate(Exchange, Exchange) method corresponds to the original exchange, the second parameter the resource exchange.

Here’s an example for implementing an AggregationStrategy, which merges the two data as a String with colon separator:

public class ExampleAggregationStrategy implements AggregationStrategy {

    public Exchange aggregate(Exchange newExchange, Exchange oldExchange) {
        // this is just an example, for real-world use-cases the
        // aggregation strategy would be specific to the use-case

        if (newExchange == null) {
            return oldExchange;
        }
        Object oldBody = oldExchange.getIn().getBody();
        Object newBody = newExchange.getIn().getBody();
        oldExchange.getIn().setBody(oldBody + ":" + newBody);
        return oldExchange;
    }

}

In the example Camel will call the http endpoint to collect some data, that will then be merged with the original message using the AggregationStrategy:

  • Java

  • XML

  • YAML

AggregationStrategy aggregationStrategy = ...

from("direct:start")
  .enrich("http:remoteserver/foo", aggregationStrategy)
  .to("mock:result");
  <route>
    <from uri="direct:start"/>
    <enrich aggregationStrategy="myStrategy">
      <constant>http:remoteserver/foo</constant>
    </enrich>
    <to uri="mock:result"/>
  </route>
- route:
    from:
      uri: direct:start
      steps:
        - enrich:
            expression:
              constant: http:remoteserver/foo
            aggregationStrategy: "#myStrategy"
        - to:
            uri: mock:result
- beans:
    - name: myStrategy
      type: com.foo.ExampleAggregationStrategy

Aggregation Strategy is optional

The aggregation strategy is optional. If not provided, then Camel will just use the result exchange as the result.

The following example:

  • Java

  • XML

  • YAML

from("direct:start")
  .enrich("http:remoteserver/foo")
  .to("direct:result");
<route>
    <from uri="direct:start"/>
    <enrich>
        <constant>http:remoteserver/foo</constant>
    </enrich>
    <to uri="mock:result"/>
</route>
- route:
    from:
      uri: direct:start
      steps:
        - enrich:
            expression:
              constant: http:remoteserver/foo
        - to:
            uri: mock:result

Would be the same as using to:

  • Java

  • XML

  • YAML

from("direct:start")
  .to("http:remoteserver/foo")
  .to("direct:result");
<route>
    <from uri="direct:start"/>
    <to uri="http:remoteserver/foo"/>
    <to uri="mock:result"/>
</route>
- route:
    from:
      uri: direct:start
      steps:
        - to:
            uri: http:remoteserver/foo
        - to:
            uri: mock:result

Using dynamic uris

Both enrich and pollEnrich supports using dynamic uris computed based on information from the current Exchange. For example, to enrich from a HTTP endpoint where the header with key orderId is used as part of the content-path of the HTTP url:

  • Java

  • XML

  • YAML

from("direct:start")
  .enrich().simple("http:myserver/${header.orderId}/order")
  .to("direct:result");
<route>
  <from uri="direct:start"/>
  <enrich>
    <simple>http:myserver/${header.orderId}/order</simple>
  </enrich>
  <to uri="direct:result"/>
</route>
- route:
    from:
      uri: direct:start
      steps:
        - enrich:
            expression:
              simple:
                expression: "http:myserver/${header.orderId}/order"
        - to:
            uri: mock:result
See the cacheSize option for more details on how much cache to use depending on how many or few unique endpoints are used.

Using out-of-the-box Aggregation Strategies

The org.apache.camel.builder.AggregationStrategies is a builder that can be used for creating commonly used aggregation strategies without having to create a class.

For example, the ExampleAggregationStrategy from previously can be built as follows:

AggregationStrategy agg = AggregationStrategies.string(":");

There are many other possibilities with the AggregationStrategies builder, and for more details see the AggregationStrategies javadoc.

See More

See Poll Enrich EIP

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