If you didn’t read the intro on Mozaïk extension clients, then you should consider reading it first.
When you register your extension’s client to Mozaïk, you have the ability to pass a mode which determine how the data will be pulled from your external service to Mozaïk.
poll mode is the default mode set when you register a client to Mozaïk.
It’s useful when you want your client to fetch data from an external service at a given interval.
See this page for usage.