docs/user-manual/modules/ROOT/pages/normalizer.adoc

[[Normalizer]]
= Normalizer

Camel supports the
https://www.enterpriseintegrationpatterns.com/patterns/messaging/Normalizer.html[Normalizer]
from the xref:enterprise-integration-patterns.adoc[EIP patterns] book.

The normalizer pattern is used to process messages that are semantically equivalent,
but arrive in different formats. The normalizer transforms the incoming messages into a common format.

image::eip/NormalizerDetail.gif[image]

In Apache Camel, you can implement the normalizer pattern by combining a xref:content-based-router-eip.adoc[Content Based Router],
which detects the incoming message's format, with a collection of different xref:message-translator.adoc[Message Translator]'s,
which transform the different incoming formats into a common format.

== Sample

This example shows a Message Normalizer that converts two types of XML messages into a common format.
Messages in this common format are then filtered.

[source,java]
----
// we need to normalize two types of incoming messages
from("direct:start")
    .choice()
        .when().xpath("/employee").to("bean:normalizer?method=employeeToPerson")
        .when().xpath("/customer").to("bean:normalizer?method=customerToPerson")
    .end()
    .to("mock:result");
----

In this case we're using a Java bean as the normalizer. The class looks like this

[source,java]
----
// Java
public class MyNormalizer {
    public void employeeToPerson(Exchange exchange, @XPath("/employee/name/text()") String name) {
        exchange.getOut().setBody(createPerson(name));
    }

    public void customerToPerson(Exchange exchange, @XPath("/customer/@name") String name) {
        exchange.getOut().setBody(createPerson(name));
    }

    private String createPerson(String name) {
        return "<person name=\" + name + \"/>";
    }
}
----

The same example in the XML DSL

[source,xml]
----
<camelContext xmlns="http://camel.apache.org/schema/spring">
  <route>
    <from uri="direct:start"/>
    <choice>
      <when>
        <xpath>/employee</xpath>
        <to uri="bean:normalizer?method=employeeToPerson"/>
      </when>
      <when>
        <xpath>/customer</xpath>
        <to uri="bean:normalizer?method=customerToPerson"/>
      </when>
    </choice>
    <to uri="mock:result"/>
  </route>
</camelContext>

<bean id="normalizer" class="org.apache.camel.processor.MyNormalizer"/>
----