ipybus is an ipywidgets see enabling communication between frontend and backend
- when creating an ipybus.Base() object, you can set a variable name which will be accessible in the window spacename
- this frontend variable can be used in javascript to set a new value and send it to the backend
- The notebook developper can then create scripts in the frontend which send values to the backend
See the wired-elements-ipybus Notebook for more insights