What is Windows Installer
A packaging format and engine for the installation, maintenance, and removal of software. Includes a GUI framework, automatic generation of the uninstallation sequence and deployment capabilities for corporate networks., The Windows Installer (previously known as Microsoft Installer) is a software component used for the installation, maintenance, and removal of software on modern Microsoft Windows systems. The installation information, and often the files themselves, are packaged in installation packages, loosely relational databases structured as OLE COM Structured Storages and commonly known as “MSI files”, from their default file extension. Windows Installer contains significant changes from its predecessor, Setup API. New features include a GUI framework and automatic generation of the uninstallation sequence. Windows Installer is positioned as an alternative to stand-alone executable installer frameworks such as older versions of InstallShield and Wise (later versions of both products are based on Windows Installer) and NSIS.
Microsoft encourages third parties to use Windows Installer as the basis for installation frameworks, so that they synchronize correctly with other installers and keep the internal database of installed products consistent. Important features such as rollback and versioning depend on a consistent internal database for reliable operation.
Logical structure of packages
A package describes the installation of one or more full products (Windows Installer does not handle dependencies between products) and is universally identified by a GUID (the PackageCode property). A product is made up of components, grouped into features.
Products
A single, installed, working program (or set of programs) is a product. A product is identified by a unique GUID (the ProductCode property) provides an authoritative identity throughout the world. The GUID, in combination with the version number (ProductVersion property) allow for release management of the software’s files and registry keys. A product is not the same as a package: a package is identified by a unique GUID (stored in the Summary Information Stream) and provides identity and release management for all the contents of the .MSI file. Release management of a Product pertains only to changes in the files and registry keys that make up a software application. Release management of a package includes the package logic and other meta data that relates to how the package executes when running. For example, changing an EXE in the software application may require the ProductCode and/or ProductVersion to be changed for release management of the software application. Only adding a launch condition (with the software application remaining exactly the same as the previous version) would still require the PackageCode to change for release management of the .MSI file itself.
Features
A feature is a hierarchical group of components
