[[ScriptingLanguages-ScriptingLanguages]]
= Scripting Languages

Camel supports a number of scripting languages which can be used to
create an Expression or
Predicate via the standard
http://jcp.org/en/jsr/detail?id=223[JSR 223] which is a standard part of
Java 6.

The following scripting languages are integrated into the DSL:

[width="100%",cols="50%,50%",options="header",]
|=======================================================================
|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 http://jcp.org/en/jsr/detail?id=223[JSR 223] scripting
language can be used using the generic DSL methods.

[[ScriptingLanguages-ScriptContext]]
== ScriptContext

The JSR-223 scripting languages ScriptContext is pre configured with the
following attributes all set at `ENGINE_SCOPE`:

[width="100%",cols="30%,30%,40%",options="header",]
|=======================================================================
|Attribute |Type |Value

|context |`org.apache.camel.CamelContext` |The Camel Context ( It cannot be used in groovy)

|camelContext |`org.apache.camel.CamelContext` |The Camel Context

|exchange |`org.apache.camel.Exchange` |The current Exchange

|request |`org.apache.camel.Message` |The message (IN message)

|response |`org.apache.camel.Message` |*Deprecated*: The OUT message. The OUT message if null by default. Use
IN message instead.

|properties |`org.apache.camel.builder.script.PropertiesFunction` |*Camel 2.9:* Function with a `resolve` method to make it easier to use
Camels xref:components::properties-component.adoc[Properties] component from scripts. See
further below for example.
|=======================================================================

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

[[ScriptingLanguages-AdditionalargumentstoScriptingEngine]]
== Additional arguments to ScriptingEngine

*Since Camel 2.8*

You can provide additional arguments to the `ScriptingEngine` using a
header on the Camel message with the key `CamelScriptArguments`. 
See this example:

[[ScriptingLanguages-Usingpropertiesfunction]]
== Using properties function

*Since Camel 2.9*

If you need to use the xref:components::properties-component.adoc[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, which key is provided in a header named "foo".

[source,java]
--------------------------------------------------------------------------------------------------------------
.setHeader("myHeader").groovy("context.resolvePropertyPlaceholders('{{' + request.headers.get('foo') + '}}')")
--------------------------------------------------------------------------------------------------------------

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

[source,java]
-------------------------------------------------------------------------------
.setHeader("myHeader").groovy("properties.resolve(request.headers.get('foo'))")
-------------------------------------------------------------------------------

[[ScriptingLanguages-Loadingscriptfromexternalresource]]
== Loading script from external resource

*Since 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:

[source,java]
-------------------------------------------------------------------
.setHeader("myHeader").groovy("resource:classpath:mygroovy.groovy")
-------------------------------------------------------------------

[[ScriptingLanguages-Howtogettheresultfrommultiplestatementsscript]]
== How to get the result from multiple statements script

*Since Camel 2.14*

As the scripteengine evale method just return a Null if it runs a
multiple statments script. Camel now look up the value of script result
by using the key of "result" from the value set. If you have multiple
statements script, you need to make sure you set the value of result
variable as the script return value.

[source,text]
-------------------------------------------------------------
bar = "baz";
# some other statements ... 
# camel take the result value as the script evaluation result
result = body * 2 + 1
-------------------------------------------------------------

 

[[ScriptingLanguages-Dependencies]]
== 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).

[source,xml]
---------------------------------------
<dependency>
  <groupId>org.apache.camel</groupId>
  <artifactId>camel-script</artifactId>
  <version>x.x.x</version>
</dependency>
---------------------------------------

