Patching With Windows Installer 3.0

The Windows Installer 3.0 supports a more reliable patching process through “patch families.” A patch family is a developer-defined sequence of patches for an application. Shown here is the state of an application on a computer in which a full release has been installed (Version 1.0), followed by three patches in a specific family: Hotfix 1, Service Pack 1, and Hotfix 3. One published hotfix from the family, Hotfix 2, is missing from the computer. Also shown is the state of a Windows Registry key (DefaultSecurity) used by the application that is introduced in Service Pack 1 and updated by Hotfix 2 and Hotfix 3.

To install a patch such as Hotfix 2, the Windows Installer 3.0 conceptually takes the application back to the state it was in after installation of the most recent “baseline” version (full release or service pack). The most recent baseline is Service Pack 1 on the computer shown here. The Installer then installs the new patch and any previously installed patches in the sequence specified for the family. In this case, Hotfix 2 is installed, followed by Hotfix 3. In the resulting state, the DefaultSecurity key has the value “High.”