Is it possible to receive a JSON object from a plugin and then pass it to a JavaScript function

I am from an asp.net background, I use to define an Ajax link inside a view that perform the following:-

1. calls an action method inside a controller class.
2. The action method will call an external web service.
3. Pass the JSON returned from this action method call to a JavaScript function inside the view.

So I need to do the same using joget forms:-

1. To define an Ajax link inside a custom HTML in a joget form that calls a plugin.
2. The plugin will call an external web service.
3. Pass the JSON returned from this plugin to a JavaScript function.
   

So can anyone gives me an example or help on how to write the following:-

1. a plugin that calls a web service.

2. and how to call this plugin from an Ajax link inside a joget form.