Scripting Languages

Camel supports a number of scripting languages which can be used to create an Expression or Predicate via the standard JSR 223 which is a standard part of Java 6.

The following scripting languages are integrated into the DSL:

Language	DSL keyword
EL	`el`
Groovy	`groovy`
JavaScript	`javaScript`
JoSQL	`sql`
JXPath	`jxpath`
MVEL	`mvel`
OGNL	`ognl`
PHP	`php`
Python	`python`
Ruby	`ruby`
XPath	`xpath`
XQuery	`xquery`

However any JSR 223 scripting language can be used using the generic DSL methods.

`ScriptContext` Options

The JSR-223 scripting language's ScriptContext is pre-configured with the following attributes all set at ENGINE_SCOPE.

Attribute	Type	Value
`camelContext`	`org.apache.camel.CamelContext`	The Camel Context.
`context`	`org.apache.camel.CamelContext`	The Camel Context (cannot be used in groovy).
`exchange`	`org.apache.camel.Exchange`	The current Exchange.
`properties`	`org.apache.camel.builder.script.PropertiesFunction`	Camel 2.9: Function with a `resolve` method to make it easier to use Camels Properties component from scripts. See further below for example.
`request`	`org.apache.camel.Message`	The `IN` message.
`response`	`org.apache.camel.Message`	Deprecated: The `OUT` message. The `OUT` message is `null` by default. Use the `IN` message instead.

See Scripting Languages for the list of languages with explicit DSL support.

Passing Additional Arguments to the `ScriptingEngine`

Available from Camel 2.8

You can provide additional arguments to the ScriptingEngine using a header on the Camel message with the key CamelScriptArguments.

Example:

public void testArgumentsExample() throws Exception {
    getMockEndpoint("mock:result").expectedMessageCount(0);
    getMockEndpoint("mock:unmatched").expectedMessageCount(1);

    // additional arguments to ScriptEngine
    Map<String, Object> arguments = new HashMap<>();
    arguments.put("foo", "bar");
    arguments.put("baz", 7);

    // those additional arguments is provided as a header on the Camel Message
    template.sendBodyAndHeader("direct:start", "hello", ScriptBuilder.ARGUMENTS, arguments);

    assertMockEndpointsSatisfied();

Using Properties Function

Available from Camel 2.9

If you need to use the Properties component from a script to lookup property placeholders, then its a bit cumbersome to do so. For example, to set a header name myHeader with a value from a property placeholder, whose key is taken from a header named foo.

.setHeader("myHeader").groovy("context.resolvePropertyPlaceholders('{{' + request.headers.get('foo') + '}}')")

From Camel 2.9: you can now use the properties function and the same example is simpler:

.setHeader("myHeader").groovy("properties.resolve(request.headers.get('foo'))")

Loading Script From External Resource

Available from 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 e.g. to refer to a file on the classpath you can do:

.setHeader("myHeader").groovy("resource:classpath:mygroovy.groovy")

How to Get the Result from Multiple Statements Script

Available from Camel 2.14

The script engine's eval method returns a null when it runs a multi-statement script. However, Camel can look up the value of a script's result by using the key result from the value set. When writing a multi-statement script set the value of the result variable as the script return value.

textbar = "baz"; # some other statements ... # camel take the result value as the script evaluation result result = body * 2 + 1

Dependencies

To use scripting languages in your camel routes you need to add the a dependency on camel-script which integrates the JSR-223 scripting engine.

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-script</artifactId>
 <version>x.x.x</version>
</dependency>

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