Several challenges can arise when you try to move your applications from an operating system like Windows XP to one like Windows Vista because the underlying code for Vista is so completely different from the one for XP.
When you do begin to test your applications on Vista, you'll find these three major categories of compatibility concerns:
- Release-related issues
- User experience
Vista sports a brand-new interface, one that relies on the "aero glass effect." This causes two changes that may affect your applications. The first relates to the Desktop Windows Manager, which is now designed to support special effects such as Flip3D as well as thumbnail previews when you move your mouse along open applications in the taskbar. Effects may be minor — for example, users may not be able to see the application preview in the taskbar.
Another effect is the Windows Shell itself. Because the Vista Shell supports new themes, older applications may not work properly in certain desktop layouts. In both cases, you should test applications and warn users of potential inconsistencies.
Another change is actually a boon to all users. It is the ability to use Fast User Switching in an Active Directory domain. Previously, you could use this feature at home only in versions of Windows that ran in a workgroup mode. Many home users have found this new feature quite valuable because they do not have to log off the current user to use a computer, just change users.
In enterprises, this is a great feature because technicians no longer need to log off users or — even worse ¬— ask for their passwords to test or fix an issue with PCs. Also, manufacturing organizations that work 24/7 no longer need to work with generic accounts; they can assign accounts to each user because they don't have to close a session to change users. However, verify that your key applications will support this feature.
Another major change is the Vista User Profile, whose name and folder structure has changed significantly. Information is now stored in the Users folder, not Documents and Settings, and several new folders have been added to support Vista's new file features. Microsoft has implemented junction points — special file system components that automatically redirect applications to appropriate locations transparently. But you should still test applications thoroughly.
There are some other minor changes that affect how users interact with Vista. Printing now uses only user-mode drivers, Help File formats have changed and no longer support the .CHM or .HLP formats, and some components are no longer available. Rely on the following table to identify these and other potential issues in Vista application compatibility:
|Desktop Windows Manager (DWM)||Supports new features such as Flip3D.||Test your applications for DWM compatibility and warn users of potential incompatibilities or inconveniences.|
|Shell changes||Vista includes new user interface themes. Applications may cause operational issues.||Run applications in appropriate compatibility mode.|
|Fast User Switching (FAS)||Supported in Vista even when joined to an Active Directory domain.||Test your applications for FAS compatibility.|
|User Profile Changes||Documents and Settings folder is replaced and split in two. The Users folder includes all user data, and ProgramData includes global application settings.||Run applications in appropriate compatibility mode and make sure they do not rely on hard-coded values.|
|Kernel Mode Printer Drivers||Vista allows only user mode drivers. Vista does not support kernel mode printers.||Update all printer drivers to user mode.|
|Help File Formats||Vista does not use .CHM or .HLP Help File formats.||Help is all based on XML data structures. Update or convert all Help files.|
|FrontPage Server Extensions, POP3 services, Services for Macintosh||Those components are deprecated or are no longer available.||Windows SharePoint Services replaces FrontPage extensions. Services for Unix replace the previous Macintosh services.|
Of the three different categories of potential application compatibility issues with Vista, the user interface changes are the easiest to deal with. However, make sure your transition plans include verification steps for each one of the issues in the three categories. Otherwise, your users may end up facing issues and your help desk calls may increase.
Be proactive. Test everything beforehand. It is by far the best approach to Vista migration.
Danielle Ruest and Nelson Ruest are IT professionals specializing in systems administration, migration planning, software management and architecture design. Danielle is a Microsoft MVP in virtualization, and Nelson is a Microsoft MVP in Windows Server. They are authors of several books about Windows, including The Definitive Guide to Vista Migration as well as The Complete Reference to Windows Server 2008.