Windows Installer (msiexec.exe, previously known as Microsoft Installer,

codename A code name, call sign or cryptonym is a code word or name used, sometimes clandestinely, to refer to another name, word, project, or person. Code names are often used for military purposes, or in espionage. They may also be used in industrial c ...

Darwin) is a

software component Component-based software engineering (CBSE), also called component-based development (CBD), is a branch of software engineering that emphasizes the separation of concerns with respect to the wide-ranging functionality available throughout a give ...

and

application programming interface An application programming interface (API) is a way for two or more computer programs to communicate with each other. It is a type of software interface, offering a service to other pieces of software. A document or standard that describes how ...

(API) of

Microsoft Windows Windows is a group of several proprietary graphical operating system families developed and marketed by Microsoft. Each family caters to a certain sector of the computing industry. For example, Windows NT for consumers, Windows Server for ...

used for the installation, maintenance, and removal of software. The installation information, and optionally the files themselves, are packaged in ''installation packages'', loosely

relational database A relational database is a (most commonly digital) database based on the relational model of data, as proposed by E. F. Codd in 1970. A system used to maintain relational databases is a relational database management system (RDBMS). Many relati ...

s structured as COM Structured Storages and commonly known as "MSI files", from their default

filename extension A filename extension, file name extension or file extension is a suffix to the name of a computer file (e.g., .txt, .docx, .md). The extension indicates a characteristic of the file contents or its intended use. A filename extension is typically ...

s. The packages with the file extensions mst contain Windows Installer "Transformation Scripts", those with the msm extensions contain "Merge Modules" and the file extension pcp is used for "Patch Creation Properties". Windows Installer contains significant changes from its predecessor, Setup API. New features include a

GUI The GUI ( "UI" by itself is still usually pronounced . or ), graphical user interface, is a form of user interface that allows users to interact with electronic devices through graphical icons and audio indicator such as primary notation, inste ...

framework A framework is a generic term commonly referring to an essential supporting structure which other things are built on top of. Framework may refer to: Computing * Application framework, used to implement the structure of an application for an op ...

and automatic generation of the

uninstallation An uninstaller, also called a deinstaller, is a variety of utility software designed to remove other software or parts of it from a computer. It is the opposite of an installer. Uninstallers are useful primarily when software components are instal ...

sequence. Windows Installer is positioned as an alternative to stand-alone executable installer frameworks such as older versions of

InstallShield InstallShield is a proprietary software tool for creating installers or software packages. InstallShield is primarily used for installing software for Microsoft Windows desktop and server platforms, though it can also be used to manage softwar ...

and NSIS. Before the introduction of

Microsoft Store Microsoft Store (formerly known as Windows Store) is a digital distribution platform operated by Microsoft. It started as an app store for Windows 8 and Windows Server 2012 as the primary means of distributing Universal Windows Platform app ...

(then named Windows Store), Microsoft encouraged 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. Furthermore, Windows Installer facilitates the

principle of least privilege In information security, computer science, and other fields, the principle of least privilege (PoLP), also known as the principle of minimal privilege (PoMP) or the principle of least authority (PoLA), requires that in a particular abstraction la ...

by performing software installations by proxy for unprivileged users.

Logical structure of packages

A package describes the installation of one or more full ''products'' and is universally identified by a

GUID A universally unique identifier (UUID) is a 128-bit label used for information in computer systems. The term globally unique identifier (GUID) is also used. When generated according to the standard methods, UUIDs are, for practical purposes, un ...

. A product is made up of ''components'', grouped into ''features''. Windows Installer does not handle dependencies between products.

Products

A single, installed, working program (or set of programs) is a ''product''. A product is identified by a unique GUID (the ProductCode property) providing an authoritative identity throughout the world. The GUID, in combination with the version number (ProductVersion property), allows for release management of the product's files and registry keys. A ''package'' includes the package logic and other

metadata Metadata is "data that provides information about other data", but not the content of the data, such as the text of a message or the image itself. There are many distinct types of metadata, including: * Descriptive metadata – the descriptive ...

that relates to how the package executes when running. For example, changing an

EXE file .exe is a common filename extension denoting an executable file (the main execution point of a computer program) for Microsoft Windows, OS/2, and DOS. File formats There are numerous file formats which may be used by a file with a exte ...

in the product may require the ProductCode or ProductVersion to be changed for the release management. However, merely changing or adding a launch condition (with the product 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. A feature may contain any number of components and other sub-features. Smaller packages can consist of a single feature. More complex installers may display a "custom setup" dialog box, from which the user can select which features to install or remove. The package author defines the product features. A

word processor A word processor (WP) is a device or computer program that provides for input, editing, formatting, and output of text, often with some additional features. Early word processors were stand-alone devices dedicated to the function, but current ...

, 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.

Components

A ''component'' is the basic unit of a product. Each component is treated by Windows Installer as a unit. The installer cannot install just part of a component. Components can contain program files, folders,

COM Com or COM may refer to: Computing * COM (hardware interface), a serial port interface on IBM PC-compatible computers * COM file, or .com file, short for "command", a file extension for an executable file in MS-DOS * .com, an Internet top-level d ...

components,

registry Registry may refer to: Computing * Container registry, an operating-system-level virtualization registry * Domain name registry, a database of top-level internet domain names * Local Internet registry * Metadata registry, information system for re ...

keys, and shortcuts. The user does not directly interact with components. Components are identified globally by GUIDs; thus the same component can be shared among several features of the same package or multiple packages, ideally through the use of

Merge Module A merge module is a special kind of Windows Installer database that contains the components needed to install a discrete software bundle. A merge module cannot be installed alone, but must be merged into a standard Windows Installer installation d ...

Key paths

A ''key path'' is a specific file, registry key, or

ODBC In computing, Open Database Connectivity (ODBC) is a standard application programming interface (API) for accessing database management systems (DBMS). The designers of ODBC aimed to make it independent of database systems and operating systems. An ...

data source that the package author specifies as critical for a given component. Because a file is the most common type of key path, the term ''key file'' is commonly used. A component can contain at most one key path; if a component has no explicit key path, the component's destination folder is taken to be the key path. When an MSI-based program is launched, Windows Installer checks the existence of key paths. 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''. No two components should use the same key path.

Developing installer packages

Creating an installer package for a new application is not trivial. It is necessary to specify which files must be installed, to where and with what registry keys. Any non-standard operations can be done using Custom Actions, which are typically developed in DLLs. There are a number of commercial and freeware products to assist in creating MSI packages, including

Visual Studio Visual Studio is an integrated development environment (IDE) from Microsoft. It is used to develop computer programs including web site, websites, web apps, web services and mobile apps. Visual Studio uses Microsoft software development platfor ...

(natively up to VS 2010, with an extension on newer VS versions),

and

WiX Wix may refer to: Computing * WiX (Windows Installer XML Toolset), a software toolset * Wix.com, an Israeli software company providing cloud-based web development services Places * Wix, Essex Wix is a village and civil parish in the Tendring ...

. To varying degrees, the user interface and behavior may be configured for use in less common situations such as unattended installation. Once prepared, an installer package is "compiled" by reading the instructions and files from the developer's local machine, and creating the .msi file. The user interface (dialog boxes) presented at the start of installation can be changed or configured by the setup engineer developing a new installer. There is a limited language of buttons, text fields and labels which can be arranged in a sequence of dialogue boxes. An installer package should be capable of running without any UI, for what is called "unattended installation".

ICE validation

Microsoft provides a set of Internal Consistency Evaluators (ICE) that can be used to detect potential problems with an MSI database.Internal Consistency Evaluators – ICEs
/ref> The ICE rules are combined into CUB files, which are stripped-down MSI files containing custom actions that test the target MSI database's contents for validation warnings and errors. ICE validation can be performed with the Platform SDK tools Orca and msival2, or with validation tools that ship with the various authoring environments. For example, some of the ICE rules are: * ICE09: Validates that any component destined for the System folder is marked as being permanent. * ICE24: Validates that the product code, product version, and product language have appropriate formats. * ICE33: Validates that the Registry table is not used for data better suited for another table (Class, Extension, Verb, and so on). Addressing ICE validation warnings and errors is an important step in the release process.

Versions

References

External links

* {{Authority control Installation software Microsoft application programming interfaces Windows administration Windows components