Chapter 19. JavaScript

Overview

JavaScript, also known as ECMAScript is a Java-based scripting language that allows quick parsing of object. The JavaScript support is part of the camel-script module.

Adding the script module

To use JavaScript in your routes you need to add a dependency on camel-script to your project as shown in Example 19.1, “Adding the camel-script dependency”.

Example 19.1. Adding the camel-script dependency

<!-- Maven POM File -->
<properties>
  <camel-version>2.15.1.redhat-621084</camel-version>
  ...
</properties>

<dependencies>
  ...
  <dependency>
    <groupId>org.apache.camel</groupId>
    <artifactId>camel-script</artifactId>
    <version>${camel-version}</version>
  </dependency>
  ...
</dependencies>

Static import

To use the javaScript() static method in your application code, include the following import statement in your Java source files: 
import static org.apache.camel.builder.camel.script.ScriptBuilder.*;

Built-in attributes

Table 19.1, “JavaScript attributes” lists the built-in attributes that are accessible when using JavaScript.

Table 19.1. JavaScript attributes

AttributeTypeValue
contextorg.apache.camel.CamelContextThe Camel Context
exchangeorg.apache.camel.ExchangeThe current Exchange
requestorg.apache.camel.MessageThe IN message
responseorg.apache.camel.MessageThe OUT message
propertiesorg.apache.camel.builder.script.PropertiesFunctionFunction with a resolve method to make it easier to use the properties component inside scripts.
The attributes all set at ENGINE_SCOPE.

Example

Example 19.2, “Route using JavaScript” shows a route that uses JavaScript.

Example 19.2. Route using JavaScript

<camelContext>
  <route>
    <from uri="direct:start"/>
    <choice>
      <when>
        <langauge langauge="javaScript">request.headers.get('user') == 'admin'</langauge>
        <to uri="seda:adminQueue"/>
      </when>
      <otherwise>
        <to uri="seda:regularQueue"/>
      </otherwise>
    </choice>
  </route>
</camelContext>

Using the properties component

To access a property value from the properties component, invoke the resolve method on the built-in properties attribute, as follows: 
.setHeader("myHeader").javaScript("properties.resolve(PropKey)")
Where PropKey is the key of the property you want to resolve, where the key value is of String type.
For more details about the properties component, see Properties in the Apache Camel Component Reference Guide.