How can I notify an application when settings are change through another one

Question

I have two projects A and B. Where project A is a system tray application, and project B is the main application. When the user changes the settings from project B, project A needs to update itself. How can I notify project A with the changes that happen?

I have tried to use Global Events but this needs to create a new instance of app A in app B when it starts.

Answer 1

There are several options. One way is to create a named EventWaitHandle. When project B updates the settings, it sets the event. Project A has a thread that waits on that event. When it gets a notification, it updates from the settings and then resets the event. I have a simple example here: Send message from one running console app to another

That will work if project B stores the new settings somewhere where project A can read them. If you want to do it in memory (i.e. project B doesn't persist the settings), then you need to set up some type of communication between the the two processes. You can set up shared memory using a MemoryMappedFile, in which case you'll still need the event notification.

Or you could set up a Named Pipe with a server stream in project B and a client stream in project A.

Answer 2

You could also use something like NancyFX that allows self hosting to expose an HTTP endpoint from each application to allow communication without the need for a physical file.

Check out: https://github.com/NancyFx/Nancy/wiki/Self-Hosting-Nancy