Available as of Camel version 2.0
Camel allows Mvel to be used as an Expression or Predicate the DSL or Xml Configuration.
You could use Mvel to create an Predicate in a Message Filter or as an Expression for a Recipient List
You can use Mvel dot notation to invoke operations. If you for instance
have a body that contains a POJO that has a getFamiliyName
method then
you can construct the syntax as follows:
"request.body.familyName"
// or
"getRequest().getBody().getFamilyName()"
Mvel Options
The MVEL language supports 1 options, which are listed below.
Name | Default | Java Type | Description |
---|---|---|---|
trim |
|
|
Whether to trim the value to remove leading and trailing whitespaces and line breaks |
Spring Boot Auto-Configuration
When using Spring Boot make sure to use the following Maven dependency to have support for auto configuration:
<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-mvel-starter</artifactId>
<version>x.x.x</version>
<!-- use the same version as your Camel core version -->
</dependency>
The component supports 4 options, which are listed below.
Name | Description | Default | Type |
---|---|---|---|
camel.component.mvel.basic-property-binding |
Whether the component should use basic property binding (Camel 2.x) or the newer property binding with additional capabilities |
false |
Boolean |
camel.component.mvel.enabled |
Enable mvel component |
true |
Boolean |
camel.language.mvel.enabled |
Enable mvel language |
true |
Boolean |
camel.language.mvel.trim |
Whether to trim the value to remove leading and trailing whitespaces and line breaks |
true |
Boolean |
Variables
Variable | Type | Description |
---|---|---|
this |
Exchange |
the Exchange is the root object |
exchange |
Exchange |
the Exchange object |
exception |
Throwable |
the Exchange exception (if any) |
exchangeId |
String |
the exchange id |
fault |
Message |
the Fault message (if any) |
request |
Message |
the exchange.in message |
response |
Message |
the exchange.out message (if any) |
properties |
Map |
the exchange properties |
property(name) |
Object |
the property by the given name |
property(name, type) |
Type |
the property by the given name as the given type |
Samples
For example you could use Mvel inside a Message Filter in XML
<route>
<from uri="seda:foo"/>
<filter>
<mvel>request.headers.foo == 'bar'</mvel>
<to uri="seda:bar"/>
</filter>
</route>
And the sample using Java DSL:
from("seda:foo").filter().mvel("request.headers.foo == 'bar'").to("seda:bar");
Loading script from external resource
Available as of Camel 2.11
You can externalize the script and have Camel load it from a resource
such as "classpath:"
, "file:"
, or "http:"
.
This is done using the following syntax: "resource:scheme:location"
,
eg to refer to a file on the classpath you can do:
.setHeader("myHeader").mvel("resource:classpath:script.mvel")
Dependencies
To use Mvel in your camel routes you need to add the a dependency on camel-mvel which implements the Mvel language.
If you use maven you could just add the following to your pom.xml, substituting the version number for the latest & greatest release (see the download page for the latest versions).
<dependency>
<groupId>org.apache.camel</groupId>
<artifactId>camel-mvel</artifactId>
<version>x.x.x</version>
</dependency>