May I Introduce You to Isolated Storage

There was a time not too long ago when programmers could write programs that stored data files just about anywhere on the user's hard drive.

In the example below, Macro Express appears to have put its backups at C:\Program Files\Macro Express 3 (click on picture for larger view). This is a no-no in modern terms.

When the current user is not privileged (e.g., not a member of the group Administrators, Power Users, etc.), this file location and others are off-limits to the programs that the user runs.

The non-privileged user is just as likely to see a dialog explaining that the file cannot be saved.

Often times the dialog so vague that most users don't know where to go next. In this case, the disk is not full... but the destination under C:\Program Files is read-only according to the system's security configuration.

Isolated Storage

This problem is addressed under Windows by a file storage mechanism known as Isolated Storage. In general, Isolated Storage sets aside a small portion of the the local hard drive for the non-privileged user and the software she uses.

The bottom line is that the storage for one user cannot spill over into the storage of another user. Perhaps more importantly, the user cannot easily disrupt the computer's operation (e.g., installed software) by deleting, moving, or overwriting critical files.

EnvisionConnect and Isolated Storage

EnvisionConnect is a ClickOnce application and correctly uses isolated storage as follows:

• EnvisionConnect programs are cached in Isolated Storage per user
• The cached program files make EnvisionConnect launch quickly (by using the cached copy instead of downloading again)
• Temporary data are stored in Isolated Storage per user

In practical terms, it means that each user has their own sandbox in which installing, updating, and uninstalling EnvisionConnect can have no effect on any other users.

Most importantly, a casual user can have the full benefit of an actual Windows application (served over the Internet or network) without an administrator installing, updating, and managing the application at each workstation. It's best of all worlds!

Comments

[Kevin Heaton]

Macro Express puts backup copies of the macro file in the same folder as the macro file. By default, the macro file and the backups are placed in the user's My Documents folder.

To avoid the problem described, move the macro file to the My Documents folder.

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Kevin Heaton
Insight Software Solutions, Inc.
Publisher of Macro Express