MVEL

Overview

MVEL (http://mvel.codehaus.org/) is a Java-based dynamic language that is similar to OGNL, but is reported to be much faster. The MVEL support is in the camel-mvel module.

Syntax

You use the MVEL dot syntax to invoke Java methods, for example:

getRequest().getBody().getFamilyName()

Because MVEL is dynamically typed, it is unnecessary to cast the message body instance (of Object type) before invoking the getFamilyName() method. You can also use an abbreviated syntax for invoking bean attributes, for example:

request.body.familyName

Adding the MVEL module

To use MVEL in your routes you need to add a dependency on camel-mvel to your project as shown in Example 11.

Example 11. Adding the camel-mvel dependency

<!-- Maven POM File -->
<properties>
  <camel-version>2.10.0-fuse-00-05</camel-version>
  ...
</properties>

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

Built-in variables

Table 8 lists the built-in variables that are accessible when using MVEL.

Table 8. MVEL variables

Name	Type	Description
`this`	`org.apache.camel.Exchange`	The current Exchange
`exchange`	`org.apache.camel.Exchange`	The current Exchange
`exception`	`Throwable`	the Exchange exception (if any)
`exchangeID`	`String`	the Exchange ID
`fault`	`org.apache.camel.Message`	The Fault message(if any)
`request`	`org.apache.camel.Message`	The IN message
`response`	`org.apache.camel.Message`	The OUT message
`properties`	`Map`	The Exchange properties
`property(name)`	`Object`	The value of the named Exchange property
`property(name, type)`	`Type`	The typed value of the named Exchange property

Example

Example 12 shows a route that uses MVEL.

Example 12. Route using MVEL

<camelContext>
  <route>
    <from uri="seda:foo"/>
    <filter>
      <language langauge="mvel">request.headers.foo == 'bar'</language>
      <to uri="seda:bar"/>
    </filter>
  </route>
</camelContext>

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