Call is used to invoke a web service. With Call you can post parameters to a JSON web service and get the result. Calls supports simple JSON results and also reporting a success or failure condition. You can have many Calls in one page and invoke them from Actions. Actions will invoke Calls in their sorting order one after one. Depending on the action type you can leave the page to a new one and pass the Call result with Action parameters or you can stay on the current page and refresh the view to use the result data.
You can use Services and Fake Data for modeling and test scenarios.
1- Click on 'New Call' button in Calls tab.
2- Define an Id and Service URL, You can post parameters and get the response.
3- Calls are base on HTTP post. Calls has JSON Web Token in their header if the user is Logged in.
4- You can use the result from Variable Generator at the bottom of designer. You can also pass the result of a Call to another view with Action parameters.