CAF is built to leverage your existing ESB / BPM solutions to provide an Interactive Browser based Web Application.
If you already have an IS service that inserts data to your database, then the recommended way to do this is to convert the service into a web Service and drag and drop this webservice on your CAF Designer Portlet / Web App canvas. I call this approach the “Bottom Up” approach where your DB is at the bottom of the Application stack and your web front end is at the top.
I think you may be attempting to do a “Top Down” approach.
Let me know if any of this did not make sense and I am glad to assist.