Question

With Mule scripting, I am able to access a Mule Message in Groovy, JavaScript and Jython via a message variable. With JRuby I cannot:

undefined local variable or method `message' for main:Object (NameError)

Neither the Mule docs or the Internets have anything to say on this. How can I access the message from Ruby?

Code

<scripting:transformer name="SetData" doc:name="Set Data">
    <scripting:script engine="jruby">
        <scripting:text><![CDATA[File.open('/tmp/foo', 'w') { |f| f.puts message.payload }]]></scripting:text>
    </scripting:script>
</scripting:transformer>

Answer 1

Mule bound variables end up in the global scope, so you need to refer them with $name.

In your case:

<scripting:transformer name="SetData" doc:name="Set Data">
    <scripting:script engine="jruby">
        <scripting:text><![CDATA[
           File.open('/tmp/foo', 'w') { |f| f.puts $message.payload }
        ]]></scripting:text>
    </scripting:script>
</scripting:transformer>

Note that if you only need the message payload, you’d rather use $payload instead of $message.payload.

Also your transformer looks more like a component IMO: it acts on the data (writes to file) instead of transforming it. It doesn’t even have a clear return value (you sure don’t want to process the return of File.open in Mule. So a scripting:component would be more in order here.

Finally, if all you need to do is write to file, you can use a File outbound endpoint from Mule that does just that.