%appdata% for MS Access installs

Question

David Fenton recently mentioned in another thread that

"The only proper place for any Access app (since Windows 2000, in fact) is the folder the %AppData% environment variable points to."

I greatly respect David's knowledge, especially in all matters relating to Access, but I'm confused by this statement.

What is the advantage of following this advice, especially in an environment where you are going to have multiple people using the same computer to access your app?

Won't installing to this folder only install the app for one user? And if this is true, won't installing your app multiple times leave multiple, separate copies of your app on the machine? Hard drive space is cheap these days, but I still don't want a front end file and other supporting files (graphics, Word and Excel templates, etc.) copied multiple times onto a machine when one copy will do.

What are your thoughts? Am I missing something key to understanding David's advice?

Answer 1

You're running into a bit of an issue here, because you're thinking about the environment variable name %appdata%. That variable stores the directory returned by SHGetSpecialFolderPath(CSIDL_APPDATA).

What you're looking for is the directory returned by SHGetSpecialFolderPath(CSIDL_COMMON_APPDATA). There's no environment variable for that directory. This directory is (as the name indicates) common to all users.

The advantage of David's method is that the Access data is protected by NTFS access rights, when it's in CSIDL_APPDATA. A user can only delete his copy. In CSIDL_COMMON_APPDATA, anyone can delete the single shared copy.

Answer 2

It's probably always best to put these advice and tips into perspective. The assumption being made here is if your application is going to be utilized in a multi user mode (that means more than one user in the application of the same time), then it's pretty much assumed that your applications going to be split into two parts. The so called application part (front end), and then the data file only part, or so called backend part.

So, you have a FE and a BE.

In this environment, each individual user within your office will have their own copy of the application placed on their workstation. The BE (data file) is thus assumed to be placed on some share folder on a server.

In the case we're not going to have multiple users running this application, or the application is not really under development, then you really don't need to split your application into two parts. However if you split your application, it means all of your users can safely work and utilize your application while you work on a copy of the next great version of this application release. Without a split environment, you really can't have any workable development cycle.

It is a long time and honored suggestion that if you're going to use access in a multi user environments, each individual user must have a copy of the front end application placed on each individual computer. If you avoid this suggestion, the end result is instability in the general operation of your application.

I have an article here that explains on a conceptual level and doesn't just tell you two split your application, but explains well why you should split your application:

http://www.members.shaw.ca/AlbertKallal/Articles/split/index.htm

Answer 3

If everything is always the same for every user on a given machine, then multiple copies of a file may not be such a good idea. But when that one exception occurs, you've painted yourself into a corner. They may need a different template version for example.

You seem to be in a rare situation for an Access developer.

Answer 4

First off, this is an issue only for a workstation that has multiple users logging on to it. That's pretty uncommon, isn't it?

Second, you admit there's no issue with disk space, so the only real issue is keeping the front end up-to-date, and that issue is really completely orthogonal to the question of where the front end is being stored.

That issue can be addressed by using any of a number of solutions that automatically copy a new version of the front end when the user opens it (if needed). Tony Toews's Auto FE Updater is the best solution I know of. It's quite versatile and easy to use, and Tony's constantly improving it.

So, in short, I don't think there's any issue here at all.

Answer 5

Yes, this is an issue but the only way around it is, assuming the IT admins allow it, to create a folder in the root of C drive and install the Access FE database file in that folder. That said I'd stil use the Application Data folder even if files are duplicated. As you state hard drives are cheap.

This assumes you don't mean a Terminal Server/Citrix system where users are simultaneously logged into the system.