Chapter 23. MVEL

Overview

MVEL 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:

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getRequest().getBody().getFamilyName()

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:

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request.body.familyName

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 23.1, “Adding the camel-mvel dependency”.

Example 23.1. Adding the camel-mvel dependency

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<!-- Maven POM File -->
<properties>
  <camel-version>2.21.0.fuse-740039-redhat-00001</camel-version>
  ...
</properties>

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

<!-- Maven POM File -->
<properties>
  <camel-version>2.21.0.fuse-740039-redhat-00001</camel-version>
  ...
</properties>

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

Built-in variables

Table 23.1, “MVEL variables” lists the built-in variables that are accessible when using MVEL.

Table 23.1. 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 23.2, “Route using MVEL” shows a route that uses MVEL.

Example 23.2. Route using MVEL

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

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

Overview

Syntax

Adding the MVEL module

Built-in variables

Example

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