I would create an infrastructure like this. If it was a windows application running online, I would create an infrastructure and listen to a desktop program or a server. When I post data from the mobile application, I would directly capture and issue a notification in my windows application.
I've done this two ways before, with MQTT and monitoring a port on the PC. If you're going to go the port route, I would suggest you code a VB.NET class that handles the prefixing mode that B4X uses, it is far more reliable receiving packets.