If there is a mismatch between the current system state and the value specified in the MSI package (e.g., a key file is missing), the related feature is re-installed.
This process is known as self-healing or self-repair. The user interface phase typically queries the target system, displays an installation wizard and enables the user to change various options that will affect the installation.
However, merely changing or adding a launch condition (with the product remaining exactly the same as the previous version) would still require the Package Code to change for release management of the MSI file itself. A feature may contain any number of components and other sub-features.
More complex installers may display a "custom setup" dialog box, from which the user can select which features to install or remove. A word processor, for example, might place the program's core file into one feature, and the program's help files, optional spelling checker and stationery modules into additional features. Each component is treated by Windows Installer as a unit.
) is a software component and application programming interface (API) of Microsoft Windows used for the installation, maintenance, and removal of software.
The installation information, and optionally the files themselves, are packaged in installation packages, loosely relational databases structured as COM Structured Storages and commonly known as "MSI files", from their default filename extensions.
A key path is a specific file, registry key, or ODBC data source that the package author specifies as critical for a given component.