I couldn't find any posts here that would discuss the events based (connect & listen) or direct communication between the 2 applications. So I'd like to ask few questions and let's consider two applications "A" and "B"
Is it possible for one application to register to events to the system that would be available for all apps?
Is it possible for application "A" to connect and listen to events of application "B" if this is installed?
Is it possible for "A" to directly communicate with "B" ?
I'm aware of security concerns of 3) so I reckon that option is not valid anymore. But 1 and 2 are the ones I'm interested in.
Thank you
In case of UWP I think the technology that you are looking for is app services.
In short, you can publish a service in an app and consume that service in an another one. It's not exactly the publisher-describer scenario - like in case of events -, since in case of app services, the consumer asks for the data and doesn't wait for it. So it's more like a pull model, looking from the 'client' app's side, rather than a push model, looking from the 'server' app's side. For a detailed example, check this article.
Your other option for app-to-app communication is launching another app from your app that can handle a certain URI. You can also send relevant data to the launched app to deal with. See this one for further information on the topic.