Content Enricher

Camel supports the Content Enricher from the EIP patterns.

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

Using Enrich EIP
Using a Message Translator
Using a Processor with the enrichment programmed in Java
Using a Bean EIP with the enrichment programmed in Java

The most natural Camel approach is using Enrich EIP.

Content enrichment using a Message Translator

You can consume a message from one destination, transform it with something like Velocity, XQuery, or AtlasMap and then send it on to another destination.

from("activemq:My.Queue")
    .to("velocity:com/acme/MyResponse.vm")
    .to("activemq:Another.Queue");

And in XML

<route>
  <from uri="activemq:My.Queue"/>
  <to uri="velocity:com/acme/MyResponse.vm"/>
  <to uri="activemq:Another.Queue"/>
</route>

You can also enrich the message in Java DSL directly (using fluent builder) as an Expression. In the example below the message is enriched by appending ` World!` to the message body:

from("direct:start")
    .setBody(body().append(" World!"))
    .to("mock:result");

The fluent builder is not available in XML or YAML DSL, instead you can use Simple language:

<route>
  <from uri="direct:start"/>
  <setBody>
    <simple>${body} World!</simple>
  </setBody>
  <to uri="mock:result"/>
</route>

Content enrichment using a Processor

In this example we add our own Processor using explicit Java to enrich the message:

from("direct:start")
    .process(new Processor() {
        public void process(Exchange exchange) {
            Message msg = exchange.getMessage();
            msg.setBody(msg.getBody(String.class) + " World!");
        }
    })
    .to("mock:result");

Content enrichment using a Bean EIP

we can use Bean EIP to use any Java method on any bean to act as content enricher:

from("activemq:My.Queue")
    .bean("myBeanName", "doTransform")
    .to("activemq:Another.Queue");

And in XML DSL:

<route>
    <from uri="activemq:Input"/>
    <bean ref="myBeanName" method="doTransform"/>
    <to uri="activemq:Output"/>
</route>

Content enrichment using Enrich EIP

Camel comes with two kinds of Content Enricher EIPs:

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 a FTP file.

For more details see Enrich EIP and Poll Enrich EIP.