# Constant

## Overview

The constant language is a trivial built-in language that is used to specify a plain text string. This makes it possible to provide a plain text string in any context where an expression type is expected.

## Example

The code shown in Example 1, “Using the constant language” sets the `username` header to the value `Jane Doe`.

Example 1. Using the constant language

    <camelContext>
      <route>
        <from uri="SourceURL"/>
        <setHeader headerName="username">
          <constant>Jane Doe</constant>
        </setHeader>
        <to uri="TargetURL"/>
      </route>
    </camelContext>