Action service sample code

In Axelor documentation (link below) there is a section on action service. We call actions through web service. Here is the documentation link:
https://docs.axelor.com/adk/7.1/dev-guide/web-services/advanced.html

The part I am not clear is about the JSON string we send to the server. The example given there is like this:
{
« action »: « check-order-dates,com.axelor.sale.web.SaleOrderController:calculate »,
« data »: {
« context »: {
« id »: 1,

},
}
}

What items should be included in « context »? Each action may have different parameters. Is there any place that I can refer to, for that?

Can someone post a working sample of action service here?