Has anybody developed some custom endpoints for Notifications 2016. Any code snippets ...?
Yes, and no.
Yes, I've converted one of our custom delivery channels into a (soap) web service, and configured a 2016 web service endpoint in PI System Explorer to use my custom web service.
But endpoints aren't customizable like we used to be able to do. If anyone's been able to do custom stuff here, it's not documented functionality. I would wait until 2017 is out, where it's rumoured that RESTful webservices are supported (and not just SOAP, like today), with some better integration with PSE than we have today.
It does have plugins ... so I would assume to can create your own ...
Yes, it is possible to create your own PI System Explorer plugins, but that's undocumented functionality. I have experimented with that, but not with endpoints. The solutions we provide as an OSIsoft partner will follow the recommended strategy from OSIsoft anyways, but for internal stuff or custom work for specific customers it could be interesting to know if it's possible
Sadly, custom delivery channels are not supported in Notifications 2016. You can learn more about which PI Notifications 2012 features are not supported here.
Retrieving data ...