Chapter 18. Header

The header language provides a convenient way of accessing header values in the current message. When you supply a header name, the header language performs a case-insensitive lookup and returns the corresponding header value.

The header language is part of camel-core.

For example, to resequence incoming exchanges according to the value of a SequenceNumber header (where the sequence number must be a positive integer), you can define a route as follows:

<camelContext xmlns="http://camel.apache.org/schema/spring">
  <route>
    <from uri="SourceURL"/>
    <resequence>
      <language language="header">SequenceNumber</language>
    </resequence>
    <to uri="TargetURL"/>
  </route>
</camelContext>

The same route can be defined in Java, as follows:

from("SourceURL")
  .resequence(header("SequenceNumber"))
  .to("TargetURL");