Automating Client Installation and Upgrade
Automating Client Installation and Upgrade |
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Windows Installer Service is a Windows 2000 component that standardizes the way applications are installed on multiple computers.
When you install applications without using Windows Installer Service, every application must have its own setup executable file or script. Each application has to ensure that the proper installation rules (for example, rules for creating file versions) are followed. This is because the application setup was not an integral part of the operating system development, so no central reference for installation rules exists.
Windows Installer Service implements all the proper Setup rules in the operating system itself. To follow those rules, applications must be described in a standard format known as a Windows Installer package. The data file containing the format information is known as the Windows Installer package file and has an .msi extension. Windows Installer Service uses the Windows Installer package file to install the application.
The following terms are used to describe the installation process that uses Windows Installer technology:
Resource. A file, registry entry, shortcut, or other element that an installer typically delivers to a computer.
Component. A collection of files, registry entries, and other resources that are installed or uninstalled as a unit. When a particular component is selected for installation or removal, all of the resources in that component are either installed or removed.
Feature. The granular pieces of an application that a user can choose to install. Features typically represent the functional features of the application itself.
Product. A single product, such as Microsoft® Office. Products contain one or more features.
The package file is a database format that is optimized for installation performance. Generally, this file describes the relationships between features, components, and resources for a specific product.
The Windows Installer package file is typically located in the root folder of the product CD or network image, alongside the product files. The product files can exist as compressed files known as cabinet files (which have a .cab extension). Each product has its own package file. At installation time, Windows Installer Service opens up the package file for the product in question, and uses the information inside the Windows Installer package to determine all the installation operations that must be performed for that product.