Language
Available as of Camel 2.5
The language component allows you to send Exchange to an endpoint which executes a script by any of the supported Languages in Camel.
By having a component to execute language scripts, it allows more dynamic routing capabilities. For example by using the Routing Slip or Dynamic Router EIPs you can send messages to language endpoints where the script is dynamic defined as well.
This component is provided out of the box in camel-core and hence no additional JARs is needed. You only have to include additional Camel components if the language of choice mandates it, such as using Groovy or JavaScript languages.
URI format
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language://languageName[:script][?options] |
And from Camel 2.11 onwards you can refer to an external resource for the script using same notation as supported by the other Languages in Camel
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language://languageName:resource:scheme:location][?options] |
URI Options
The component supports the following options.
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|| Name || Default Value || Type || Description ||
| {{languageName}} | {{null}} | {{String}} | The name of the [Language|Languages] to use, such as {{simple}}, {{groovy}}, {{javascript}} etc. This option is mandatory. |
| {{script}} | {{null}} | {{String}} | The script to execute. |
| {{transform}} | {{true}} | {{boolean}} | Whether or not the result of the script should be used as the new message body. By setting to {{false}} the script is executed but the result of the script is discarded. |
| {{contentCache}} | {{true}} | {{boolean}} | *Camel 2.9:* Whether to cache the script if loaded from a resource.
Note: from *Camel 2.10.3* a cached script can be forced to reload at runtime via JMX using the clearContentCache operation. |
| {{cacheScript}} | {{false}} | {{boolean}} | *Camel 2.13/2.12.2/2.11.3:* Whether to cache the compiled script. Turning this option on can gain performance as the script is only compiled/created once, and reuse when processing Camel messages. But this may cause side-effects with data left from previous evaluation spills into the next, and concurrency issues as well. If the script being evaluated is idempotent then this option can be turned on. |
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Message Headers
The following message headers can be used to affect the behavior of the component
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|| Header || Description ||
| {{CamelLanguageScript}} | The script to execute provided in the header. Takes precedence over script configured on the endpoint. |
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Examples
For example you can use the Simple language to Message Translator a message:
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{snippet:id=e1|lang=java|url=camel/trunk/camel-core/src/test/java/org/apache/camel/component/language/LanguageRouteTest.java} |
In case you want to convert the message body type you can do this as well:
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{snippet:id=e1|lang=java|url=camel/trunk/camel-core/src/test/java/org/apache/camel/component/language/LanguageRouteConvertBodyTest.java} |
You can also use the Groovy language, such as this example where the input message will by multiplied with 2:
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{snippet:id=e1|lang=java|url=camel/trunk/components/camel-groovy/src/test/java/org/apache/camel/language/groovy/LanguageGroovyRouteTest.java} |
You can also provide the script as a header as shown below. Here we use XPath language to extract the text from the <foo> tag.
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Object out = producer.requestBodyAndHeader("language:xpath", "<foo>Hello World</foo>", Exchange.LANGUAGE_SCRIPT, "/foo/text()");
assertEquals("Hello World", out);
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Loading scripts from resources
Available as of Camel 2.9
You can specify a resource uri for a script to load in either the endpoint uri, or in the Exchange.LANGUAGE_SCRIPT header.
The uri must start with one of the following schemes: file:, classpath:, or http:
For example to load a script from the classpath:
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{snippet:id=e1|lang=java|url=camel/trunk/camel-core/src/test/java/org/apache/camel/component/language/LanguageLoadScriptFromClasspathTest.java} |
By default the script is loaded once and cached. However you can disable the contentCache option and have the script loaded on each evaluation.
For example if the file myscript.txt is changed on disk, then the updated script is used:
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{snippet:id=e1|lang=java|url=camel/trunk/camel-core/src/test/java/org/apache/camel/component/language/LanguageLoadScriptFromFileUpdateTest.java} |
From Camel 2.11 onwards you can refer to the resource similar to the other Languages in Camel by prefixing with "resource:" as shown below:
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{snippet:id=e1|lang=java|url=camel/trunk/camel-core/src/test/java/org/apache/camel/component/language/LanguageResourceLoadScriptFromClasspathTest.java} |
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