How to Use the Custom Utility/method in the Ensemble

Hi,

We have a method written in cache studio that converts XML file to JSON and JSON file to XML,  Can we use this method in ensemble production. If so Could you please clarify as where do we define this method (Service, Process, Operation).

We also tried using the method in the Router (Custom Utility function) but we are not sure as to how to pass the input file (Basic Setting provided) from Business Service to Router & also the Output to the target file configuration mentioned in the Operations?

Also please advice on the best suited solution.

Thanks,

Sneha