SSFF EC and Rest Service Integration from external system

Dear experts,

In our client implementation of SSFF EC we would like on employee time off and time sheet submit button to trigger a call of REST Service from an external system that includes the employee actual daily rostering in a real time synchronous service. The middleware between SSFF EC Time Off and external system will be CPI.

We would like to understand how this is feasible creating a rule in which we should set the REST service URL or through a rule using intelligent services or in another way? Do you have any similar experience on this?

Thank you a lot for your support,

Best Regards,