Multi-User Database Desktop Application Design

Question

First, I apologize for the seemingly dumb question I'm not very strong with databases.

I'm re-designing a desktop application in C# for use over a local network that basically is a highly specialized ticket tracking system. Essentially when a user launches the application they'll be asked for their credentials to gain access to the system and then the application will query the central database for data (currently a MySQL server running on a local machine), displaying it on the screen.

My question is if four users are connected and two users enter new data, what is the most efficient method of letting each user know of the new data? Would it be simply to query the database and update the application with the new data on a timer? Or would creating a server application to sit in between the user and the database server to perform queries itself and notify each connected user of updated data?

Answer 1

See it all depends how important is it to notify the clients in real time about the changes in your database. If your clients have no issue with a delay of minute or two you can probably go for the timer approach. But if they really wish the data to be real time (delay of less than 1-2 sec), go for the other approach. Create a separate service which polls the database and notify the client application for any update. For this you can make use of socket listners. Hope that helps !!

Answer 2

4 users? On a local LAN? Using simple, indexed queries? Just poll the DB from the clients. Kick off a thread at application start up and have it run a query every 2-5 seconds, then notify the user using whatever is appropriate for background threads updating GUIs in .NET.

This is straightforward, don't over think it. The "hardest" part is the asynchronous notification of the user (which depending on your GUI layout and required actions is probably not a big deal either, thus the quotes).