What you need to know about Windows 8 app compatibility

Microsoft has released a document that will help you understand application program compatibility problems with the new OS

Hidden in the ballyhoo of the Windows 8 developer rollout is a gem of a document with the unlikely name of Windows and Windows Server Developer Preview Compatibility Cookbook. If you're starting to get spooked about "legacy" app compatibility with Windows 8, it's a good place to start.

(It still sends a shudder up my spine when I call Windows 7 apps "legacy.")

Microsoft distributed a similar document for Windows 7 called the Application Quality Cookbook. Like the earlier tome, this one's intended to help applications people figure out what will or won't work with the new version of Windows -- and points in the right direction to identify, if not rectify, many common problems.

Some of the highlights:

  • If your apps check for a Windows version number, they're probably going to choke. Windows 8 is identified internally (by GetVersion and GetVersionEx) as version 6.2. Go figure.
  • .Net Framework 4.5 is the default (apparently it's built into the Win8 Runtime, WinRT), but .Net Framework 3.5 can be automatically loaded, with user approval, from the Windows Update site. Some day, performing an upgrade from Windows 7 to Windows 8 Developer Preview -- the direct upgrade is not currently supported -- is supposed to bring along a copy of .Net Framework 3.5. The .Net Framework 3.5 runtime files are on the Developer Preview DVD.
  • There's a lengthy discussion of the changes made to accommodate new "advanced format" disks, with large sector sizes (up from 512 bytes to 4KB). The changes apply to all Windows systems with AF disks, under Vista, Windows 7, or Windows 8 Developer Preview. The paper also discusses application handling of Thin Provisioning LUNs for storage arrays, and the gradual elimination of the DiskPart and DiskRAID utilities in favor of the Windows Storage Management API and the PowerShell utility.
  • Windows Explorer 7's Previous Versions feature is disappearing, as well as the application hooks for it. Windows 7 Backup and Restore are similarly being deprecated, in favor of the new Windows 8 File History feature.
  • For new applications, there are much more stringent requirements for testing kernel mode drivers.
  • You can find volumes of warnings about creating autostarting programs and admonitions -- with code samples -- to turn periodic background checks into official Automatic Maintenance tasks.
  • Finally, the Compatibility Cookbook runs through new APIs for SSDs, including TRIM commands, and USB 3.0.

If you're worried that your current applications aren't going to run in Windows 8 or if you're thinking about creating applications that take advantage of the new Windows 8 capabilities, this 70-page doc is well worth a gander.

This article, "What you need to know about Windows 8 app compatibility," was originally published at InfoWorld.com. Get the first word on what the important tech news really means with the InfoWorld Tech Watch blog. For the latest business technology news, follow InfoWorld.com on Twitter.

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