[not quite OT] Serving a standalone

[Graham Samuel]

As with so much in this world, technical and otherwise, I am profoundly ignorant of the following, and I’d be grateful for any explanations, best practice etc.

The idea is as follows: 

1. I write a desktop program (OK, an app) that runs, say, on PC and Mac. Good LC territory. This program is capable of saving some parameters, files etc on behalf of the user. Some of these files will be anonymous, in that the user won’t see them or be able to change their names or file paths - they are just there to maintain the state of the program between activations - this is a very widespread notion throughout modern computing.

2. Now, some institution - like an enterprise, school etc - buys a “site license” for the app, which means they’ve paid to have (say) up to 20 simultaneous users.

3. When the purchase is made, someone (probably a technical support person) loads up the app onto a server belonging to the institution and registers it: some kind of registration file is kept on the server, controlled by the initial instance of the app (I’m sure Jacque’s Zygodact would be an excellent component of this).

4. When a user wants to run the app, they sit at their personal computer, contact the server, and download the app. This is where the fun starts.

6. What happens now when that downloaded instance of the app is called upon to save a file? Is it just saved on the local computer? If so, what if Jack and Jill both use the program on the same machine at different times? Will Jill’s files overwrite Jack’s, and if we don’t want this, how can we prevent it? How much work will the app itself have to do? I think I understand this one: the app will have to associate each file with a directory created especially for an individual. This is not hard, especially if Jack and Jill have separate user spaces - we can insist on this. But maybe these files end up on the server - does this ever happen?

7. While Jill is working, many others start work. Anselma downloads another instance of the app to her own computer. How does the original copy on the server know whether this is legit (not greater than the twentieth user in my example) or not (the 21st user), and indeed how do any of the users know the app is already registered? More particularly, how much work does the app have to do to manage this?

This is really the key question - what do servers generally do to support multiple instances as described above? Maybe it’s nothing, in which case the ‘server’ version of the app will need a lot more development work than the version intended for a single individual; or maybe it’s so much that the app doesn’t need to know anything about the server once the user has done the download.

For me this is a real case, and I just don’t know how to learn more and thus get started.

TIA for any discussion and help.

Graham