Operating System Update - Windows 8 Application Compatibility Preview

This week's Subject Matter Expert Update comes from Ben Nel, Technical Specialist.

Microsoft has just released the Windows and Windows Server Developer Preview Compatibility Cookbook. In the world of application compatibility, this will be one of the most important ingredients in determining if your applications will be compatible with the latest Microsoft operating system, just as Windows 7 and Windows Server 2008 R2 Application Quality Cookbook and Windows Vista and Server 2008 Application Compatibility Cookbook accompanied previous releases. The purpose of these documents is to introduce us to compatibility issues that may be faced when running applications on new Microsoft operating system, and the new features and enhancements that will be available.

So, what are the highlights?

• Operating System Version: The Client Operating System version number will be 6.2., Windows 7 being 6.1, Windows Vista 6.0, and Windows XP version 5.1. As this will be a minor version change it suggests that we won’t see the major architectural changes that were introduced with Windows Vista, making a transition from Windows 7 much easier than a transition from Windows XP. 

• .Net Framework 4.5 is the default and .Net Framework 3.5 is optional. If you are upgrading from Windows 7, .Net Framework 3.5 will be enabled by default. If a user wants to install applications that rely on .NetFramework 3.5 or 2.0, it will trigger a request for these files from Windows Update service. 

• Desktop apps may not be visible after launching the default web browser. By default, Internet Explorer 10 will be launched as a metro style app (full screen). You can change the behaviour by changing “Default view for links” setting in Internet Explorer. 

• Application (Execution) Manifest (introduced since Windows 7) is used to determine the operating system the application was meant to target. By default, this will be assumed as Windows Vista.  It ensures that with future releases the applications will be handled as if running on the supported OS version. An example for this is the behaviour of PCA (Program Compatibility Assistant). For example:

1. Windows Developer Preview: apps with the compatibility section do not get the PCA mitigation.
2. Windows 7: apps with the compatibility section are tracked for potential compatibility issues for Windows Developer Preview changes (described in this document).
3. Windows Vista (default): apps that fail to install properly or crash during runtime under some specific circumstances get the PCA mitigation.

• Then there is a large section on how applications address larger storage volumes. Some new functionality that has been introduced here is:

1. Expansion on the support for 4K disks that builds on what is available in Windows 7 SP1.
2. New APIs to query the physical sector size.
3. Enhanced fsutil command line utility.

• Thin Provisioning of LUNs that provides a storage service module which can be applied to client-server storage systems, virtualisation storage and cloud storage services.

• Windows 7 Backup and Restore functions will be deprecated. It was rarely used and will be replaced by the File History Feature.

• Windows Desktop Manager is always on cannot be disabled by users or applications. Applications that try to programmatically disable this Desktop Composition will get a success returned, however Desktop Composition will not be disabled.  

• Kernel mode drivers will not run if they are not signed by a trusted certificate authority and testsigning will not be permitted. This change affects all drivers for devices that support the unified extensible firmware interface and does not affect any user-mode drivers.  

• There are also a number of new features introduced, including support for USB 3.0, new API calls for storage solutions, etc.

ChangeBASE will be keeping a close eye on new developments, so watch this space!