6 Replies Latest reply on Aug 14, 2012 3:59 PM by futuredan

Error using custom language in filter

futuredan Jul 27, 2012 10:26 AM

The underlying issue that I am attempting to resolve is to be able to dynamically provide an xpath in a predicate as shown below:

However, I get the following error:

Exception java.lang.IllegalArgumentException: No script engine could be created for: myxpath

I've created a class that extends Language and created a file named myxpath in META-INF/service/org/apache/camel/language.

What else do I need to do to implement a custom language?

Edited by: futuredan on Jul 27, 2012 10:23 AM

1. Re: Error using custom language in filter

njiang Jul 27, 2012 9:31 PM (in response to futuredan)

How did you deploy your camel route?
BTW, did you have change to write a simple unit test to verify your language.

You should find some example in the unit tests of camel-core.

Willem
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2. Re: Error using custom language in filter

futuredan Jul 30, 2012 5:36 PM (in response to njiang)

I am using a bundle whose only contents is a camel-context.xml in META-INF/spring to deploy the context.

I tried creating a test case, but I'm using Fuse 4.3.1 which uses Camel 2.6 and that source isn't available anymore.
I tried coming up with something based on the Camel 2.8 source, but I'm not sure I pulled it off.

My classes are quite small. Here they are in their entirety.
I assume I am missing something necessary to create a language.
Do you know what it could be?

public class MyXpathLanguage extends XPathLanguage
{

     public MyXpathLanguage()
     {
     }

     public Predicate createPredicate( String expression )
     {
          MyXpathBuilder builder = MyXpathBuilder.xpath( expression );
          super.configureBuilder( builder );
          return builder;
     }

}

public class MyXpathBuilder extends XPathBuilder
{
     private static final Log LOG = LogFactory.getLog( MyXpathBuilder.class );

     public MyXpathBuilder( String text )
     {
          super( text );
          // TODO Auto-generated constructor stub
     }

     public static MyXpathBuilder xpath( String text )
     {
          LOG.info( "Building XPath with :" + text + ":" );
          return new MyXpathBuilder( text );
     }

     public boolean matches( Exchange exchange )
     {
          LOG.info( "Matching :" + exchange.getIn().getBody().toString() + ":" );
          return( super.matches( exchange ) );
     }
}
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3. Re: Error using custom language in filter

njiang Aug 9, 2012 10:04 PM (in response to futuredan)

It is more complicate if you want to add Spring support of the MyXpathLanguage yourself.
You need to update the camel-core to add the MyXpathLanguage into the module of language.

Willem
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4. Re: Error using custom language in filter

davsclaus Aug 13, 2012 1:31 AM (in response to futuredan)

Yeah would be nice with a dynamic xpath/xquery for predicates out of the box. I logged a JIRA ticket some time back.

So possible in the future its out of the box. But the caveat is that the dynamism may requires a change in the DSL, and thus not so easy to introduce as fast.
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5. Re: Error using custom language in filter

futuredan Aug 14, 2012 3:52 PM (in response to njiang)

So in the directive:

I can't use a value for the language attribute that isn't built into camel-core?

I had assumed languages were dynamic like components with META-INF/services/org/apache/camel/component

Thank you for the information.
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6. Re: Error using custom language in filter

futuredan Aug 14, 2012 3:59 PM (in response to davsclaus)

I see the ticket at https://issues.apache.org/jira/browse/CAMEL-3697

Thanks for the information. I'll keep an eye on that ticket.
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