You have two seperate problems :
- monitoring and copying data
- notifying clients
Monitoring: and copying the data to the database is a process that you would want to have running in the background so you can start and stop it when needed independent of your application. I would suggest making that a windows service that uses the filesystem watcher. Mind the location of the files, the uploading application and the service both need access to that location.
An older article on this can be found here http://www.codeproject.com/Articles/18521/How-to-implement-a-simple-filewatcher-Windows-serv (things have changed since 2007)
notifying your application, does it need to be real time ? When the application starts does it need to know there are new files waiting ?
If the application needs to check when starting you could simple make a table where the service keeps track on the files it has processed and that your windows app can query to see if files are waiting. If the notification does not need to be real time you could trigger the check based on a timer and you would have a pretty simple solution.
If the notification needs to be real time you need other options.
SignalR mostly is used in web apps but I have seen it work in console apps and it is pretty simple to set up and easy to use. If you download signalR https://github.com/SignalR/SignalR in the samples there is a self hosted example that might get you up to speed. Make your service the messagehub and let client applications connect on startup. SignalR is pretty new and I have not seen a lot of people use it outside of a web app so it might be a risk trying this, but it should be fun :)
If you don't want signalR and stil need real time notifications you could look at:
- have a status folder in your data folder, your service writes status files in this folder and you application watches this status folder via the fileSystem watcher, I like this because your app and the service are using the same technologies and it is always a good idea to keep the number of technologies and the number of different solutions as low as possibel.
- let the service write to a message queue and have your app monitor that (overkill in my mind)
- make your service and windows app like chat application using WCF broadcast messages. A sample to get you started : http://www.codeproject.com/Articles/19752/WCF-WPF-Chat-Application (way to much work in my mind)