Discovery service Flow

I am exploring discovery service hence I had set up the discovery service. But unfortunately unable to understand the relationship between Courses, Programs, Catalogues, Organizations, Subjects, and tag.
When I checked on swagger, I am getting null results when I call the APIs.

Please Help

There’s some documentation and many more details in the comments through the code.
If you’re using the devstack, you can access it (http://localhost:18381/ I think it was. It also has a Django admin at /admin/).
A practical exercise to start using the course-discovery components is to set up programs (a program is a group of courses).