Taking inventory of installed products, features, and components

(Short version.)

They’re not at all difficult to find, but some often overlooked MSI API functions to enumerate what’s installed on a system:

• What products are installed: MsiEnumProducts or MsiEnumProductsEx (in VBScript, Installer.Products or Installer.ProductsEx)
• What features are installed for a product: MsiEnumFeatures (Installer.Features)
• What components are installed: MsiEnumComponents (Installer.Components)

Product and component information:

• Installed product information (install location, date, version, that sort of thing): MsiGetProductInfo or MsiGetProductInfoEx (VBScript Installer.ProductInfo)
• Installed component information: MsiGetComponentPath (Installer.ComponentPath)
• Given a component, which products use it: MsiEnumClients (Installer.ComponentClients)

Product, feature, component states (installed? advertised? etc.):

• MsiQueryProductState, MsiQueryFeatureState, MsiQueryComponentState (Installer.ProductState/FeatureState/ComponentState)