MinWin
Encyclopedia
MinWin is a term used informally by Microsoft
Microsoft
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...

 to describe the kernel and operating system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...

 components that form the basis of releases of Microsoft Windows
Microsoft Windows
Microsoft Windows is a series of operating systems produced by Microsoft.Microsoft introduced an operating environment named Windows on November 20, 1985 as an add-on to MS-DOS in response to the growing interest in graphical user interfaces . Microsoft Windows came to dominate the world's personal...

 starting with Windows Vista
Windows Vista
Windows Vista is an operating system released in several variations developed by Microsoft for use on personal computers, including home and business desktops, laptops, tablet PCs, and media center PCs...

. The term was first used in 2003 to describe approximately 95% of the common components of the operating system, but has over time come to refer to a significantly smaller portion thereof. Its most recent and most well-known variation was a minimalistic, self-contained set of Windows components that shipped as part of Windows 7 and Windows Server 2008 R2
Windows Server 2008 R2
Windows Server 2008 R2 is a server operating system produced by Microsoft. It was released to manufacturing on July 22, 2009 and launched on October 22, 2009. According to the Windows Server Team blog, the retail availability was September 14, 2009. It is built on Windows NT 6.1, the same core...

.

Background

Through the history of Microsoft Windows, the core of the operating system was generally designed to be a single large, inter-related set of components. With successive releases, the set of components considered to be the core of Microsoft Windows numbered into the thousands, with numerous dependencies
Coupling (computer science)
In computer science, coupling or dependency is the degree to which each program module relies on each one of the other modules.Coupling is usually contrasted with cohesion. Low coupling often correlates with high cohesion, and vice versa...

 that prevented the company from producing a version of Microsoft Windows that (for example) didn't include the graphical user interface
Graphical user interface
In computing, a graphical user interface is a type of user interface that allows users to interact with electronic devices with images rather than text commands. GUIs can be used in computers, hand-held devices such as MP3 players, portable media players or gaming devices, household appliances and...

 and printing components. Further complicating this was the issue that many configuration tasks could only be performed using the graphical user interface. Windows reviewer Paul Thurrott
Paul Thurrott
Paul Brian Thurrott is a technology reporter, published author, podcaster, and the news editor for Windows IT Pro magazine...

 described the approach to Windows's development as "a house of cards [which] is precariously shifting in the breeze."

In an April 2003 interview coinciding with the release of Windows Server 2003
Windows Server 2003
Windows Server 2003 is a server operating system produced by Microsoft, introduced on 24 April 2003. An updated version, Windows Server 2003 R2, was released to manufacturing on 6 December 2005...

, Rob Short, the vice-president of the Windows Core Technology group, explained that creating a command-line version would involve "looking at the layers and what's available at each layer and how do we make it much closer to the thing the Linux guys have -- having only the pieces you want running. That's something Linux has that's ahead of us, but we're looking at it. We will have a command line-only version, but whether it'll have all the features in is another matter. A lot of the tools depend on having the graphical interface." Windows Server 2003 was seen by reviewers such as Direction On Microsoft's Michael Cherry as having reduced the reliance on graphical tools to configure the operating system, but the operating system itself still required the full graphical interface to be installed, even on servers where it would never be needed.

After Windows Server 2003's release, Rob Short assembled a team of kernel architects at Microsoft, with the intention of documenting and disentangling the dependencies within the core operating system. The kernel development team had realized that they were having difficulty being able to "predict the impact of changes and to make broad, cross-group changes to Windows", and the new kernel architecture team would aim to improve software engineering practices both within the Windows kernel itself, as well as with the other components of Windows. To do this, every component of the operating system (consisting of about 5,500 distinct files in late 2005, during the development of Windows Vista
Development of Windows Vista
Development of Windows Vista occurred over the span of five and a half years, starting in earnest in May 2001, prior to the release of Microsoft's Windows XP operating system, and continuing until November 2006....

) was assigned a "layer number" that represents its dependency position relative to other components, with lower-numbered components being closer to the core of the operating system, and higher numbers representing high-level components. With this information, the core architecture team began to address a range of issues where low-level components were reliant on high-level components, and finding ways to resolve those dependencies. In doing so, a number of new options for creating focused sub-sets of Windows for different purposes became possible.

Larry Osterman, a developer on the Windows Audio team at Microsoft, described the effort in a November 2008 posting to the Channel 9 discussion forum as, "refactoring code along architectural layering lines, and it's the natural extension of what we've been doing since the Longhorn Reset (so arguably Vista was the first "minwin" based operating system)." Brandon Paddock, also a Windows developer, expanded on this, saying, "It's more like a set of guidelines and principles, kind of like how SDL (Secure Development Lifecycle
Trustworthy Computing Security Development Lifecycle
The Microsoft Security Development Lifecycle is a software development process used and proposed by Microsoft to reduce software maintenance costs and increase reliability of software concerning software security related bugs. It is based on the classical spiral model.- Versions :- Further reading...

) guides our development process toward more secure software, the MinWin effort guides Windows components to fit into a more clearly and well-defined layered architecture."

Releases

While Microsoft has stated that MinWin will not be released as a stand-alone product, the various iterations of MinWin have shipped in every Windows operating system release since Windows Vista.

Windows Vista

The first use of the term "MinWin" by Microsoft was in 2003 during the development of Windows Vista
Development of Windows Vista
Development of Windows Vista occurred over the span of five and a half years, starting in earnest in May 2001, prior to the release of Microsoft's Windows XP operating system, and continuing until November 2006....

, known at the time by its codename, Longhorn. MinWin was described at the time as consisting of approximately 95% of the total Longhorn code base, with the additions for each edition of Longhorn layered on top of that. While the name MinWin was never used as part of Windows Vista's marketing efforts or in presentations to developers or IT professionals, some of the kernel architecture team's componentization and refactoring work was shipped with Windows Vista.

Windows Server 2008

One of Microsoft's goals for Windows Server 2008 was to produce a variant with a sub-set of the entire Windows operating system that contains enough components to run a number of common server roles, such as Active Directory
Active Directory
Active Directory is a directory service created by Microsoft for Windows domain networks. It is included in most Windows Server operating systems. Server computers on which Active Directory is running are called domain controllers....

, Microsoft DNS
Microsoft DNS
Microsoft DNS is the name given to the implementation of domain name system services provided in Microsoft Windows operating systems.- Overview :...

 Server, DHCP Server, and Internet Information Services
Internet Information Services
Internet Information Services – formerly called Internet Information Server – is a web server application and set of feature extension modules created by Microsoft for use with Microsoft Windows. It is the most used web server after Apache HTTP Server. IIS 7.5 supports HTTP, HTTPS,...

. During its development in 2005 and 2006, this installation option was internally called "MinWin", and sometimes externally as "Server Foundation", before its final name of Server Core was chosen. By the time Server Core was ready to be shipped with Windows Server 2008, however, the term "MinWin" had changed to describe a much smaller set of components, and its focus and intent had shifted from being a large sub-set of the complete Windows operating system with some high-level components removed, to being a small, self-contained operating system that has no dependencies on higher-level components.

Andrew Mason, the program manager at Microsoft responsible for Windows Server Core, explained in a February 2008 interview for TechNet that Windows Server 2008 (both the full installation, as well as Server Core) is built on top of this smaller set of components. In this release, MinWin is "the definition of the lowest-level pieces of the operating system", including Windows kernel, the hardware abstraction layer, file system and networking support. Other parts commonly considered part of the core operating system, such as the event logs, performance counters, Windows Management Instrumentation
Windows Management Instrumentation
Windows Management Instrumentation is a set of extensions to the Windows Driver Model that provides an operating system interface through which instrumented components provide information and notification...

, are part of Server Core.

Windows 7

In October 2007, Eric Traut
Eric Traut
Eric Traut is an American software engineer and software emulation pioneer. Traut graduated from Stanford University in 1992. From 1993 to 1995 he worked for Apple Computer, creating a Mac 68K emulator to be used in PowerPC-based Macintoshes...

, a developer at Microsoft, demonstrated a self-contained MinWin system, made up of about 100 files, on which a basic HTTP server was running. Traut noted that MinWin takes up about 25 MB
Megabyte
The megabyte is a multiple of the unit byte for digital information storage or transmission with two different values depending on context: bytes generally for computer memory; and one million bytes generally for computer storage. The IEEE Standards Board has decided that "Mega will mean 1 000...

 on disk
Hard disk
A hard disk drive is a non-volatile, random access digital magnetic data storage device. It features rotating rigid platters on a motor-driven spindle within a protective enclosure. Data is magnetically read from and written to the platter by read/write heads that float on a film of air above the...

 and has a working set
Working set
Peter Denning defines “the working set of information W of a process at time t to be the collection of information referenced by the process during the process time interval ”. Typically the units of information in question are considered to be memory pages...

 (memory usage) of 40 MB. It lacked a graphical user interface
Graphical user interface
In computing, a graphical user interface is a type of user interface that allows users to interact with electronic devices with images rather than text commands. GUIs can be used in computers, hand-held devices such as MP3 players, portable media players or gaming devices, household appliances and...

 and is interfaced using a full-screen command line interface. Traut explained during the demo that MinWin would not be offered as a stand-alone product, but would instead be used as the basis for future operating system releases such as Windows 7.

Several months after Traut's demonstration, some confusion arose from an interview by Ina Fried
Ina Fried
Ina Fried, formerly Ian Fried, is an American journalist and senior editor for All Things Digital, where she authors the blog Mobilized. Prior to that, she was a senior staff writer for CNET Network's News.com...

 of Cnet's News.com with Steven Sinofsky
Steven Sinofsky
Steven Sinofsky has been the President of the Windows Division at Microsoft since September 2008, responsible for the development and marketing of Windows, Windows Live, and Internet Explorer.-Education:...

, the vice-president of Windows engineering at Microsoft. Sinofsky described the Windows 7 kernel as a further evolution of the Windows Server 2008 kernel, itself an evolution of the Windows Vista kernel. This was interpreted by web sites such as Slashdot to mean that Windows 7 would not include MinWin. Mark Russinovich
Mark Russinovich
Mark E. Russinovich is a Technical Fellow in the Platform and Services Division at Microsoft. He was a cofounder of software producers Winternals before it was acquired by Microsoft in 2006.-Early life and education:...

 suggested that some of the confusion surrounding MinWin may be related to the imprecise use of the word "kernel"; MinWin is not, in and of itself a kernel, but rather a set of components that includes both the Windows NT Executive and several other components that Russinovich has described as "Cutler
Dave Cutler
David Neil Cutler, Sr. is an American software engineer, designer and developer of several operating systems including RSX-11M, VMS and VAXELN at Digital Equipment Corporation and Windows at Microsoft.- Personal history :...

's NT".
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