Customer function in JAVA possible?

Hi,

for some advanced string conversion I need to write my own user/ customer function. I have done this already in JAVA. Now I am looking for a way to embed this customer function into SAP Data Services 4.2. Unfortunately, I couldn't find any helpful documentation on that. So

(1) Is it possible?

(2) Where can I find a detail description on how to do it?

Wrapping my JAVA function as a web service or RFC call is not an option for me. I am looking for scalable way for just 1 JAVA method.

Thanks and Best Regards.

Markus