I have a background service that can be configured to perform some action every x minutes. I want to implement a widget that gets updated every time my service performs that
Just make yourself a RemoteViews and update the widget(s) directly in the Service. You'll get your AppWidgetManager via:
AppWidgetManager mgr=AppWidgetManager.getInstance(this);
Everything else is as normal.
Note:- If you really want to force the existing AppWidgetProvider to do the work, send a broadcast with a custom action to your component, and call onUpdate() yourself from onReceive() when you get it.