Windows Longhorn


 * For post-reset history and builds, see Windows Vista.

Longhorn was the codename for the planned successor of Windows XP.

One of the original - and largest - changes is that, with "Longhorn", the .NET Framework would be integrated into the core Windows platform, deprecating the traditional Win32 API. During development, portions of the operating system were rewritten, causing memory leaks and instability, particularly in Windows Explorer.

Development was reset, but post-reset builds continued to use the "Longhorn" codename until the final name, Windows Vista, was announced on 22 July 2005.

Codename
"Longhorn" was chosen as the codename for the operating system to represent its initial status as an internim release between Windows XP (codenamed "Whistler") and "Blackcomb". Whistler and Blackcomb are names of mountains in British Columbia, Canada, and Longhorn is the name of a saloon located in between the two mountains, representing the operating system's initial status as an internim release between the two products. Bill Gates would later state that this choice for a codename of the operating system was "a bit random".

Codebase
The popular belief is that pre-reset "Longhorn" builds are based on Windows XP. This was likely spurred by Paul Thurrott's statement on his review of build 5048: "The problem, I was told recently, was that the underpinnings of Longhorn--then based on the Windows XP code base--were struggling under the weight of all of the technologies that Microsoft planed to implement in this release." However, pre-reset "Longhorn" builds are based, not on XP, but on Windows Server 2003 release candidate code. The xpclient release branch, dedicated to XP, spun off from the main branch in 2001. The main branch continued to compile Server 2003 builds at the 3xxx range, such as build 3663 (release candidate 1), until the dnsrv branch dedicated to Server 2003 spun off from the main branch in 2002. After that, the main branch began compiling Longhorn builds.

Logos
Several different logos were created throughout the development of "Longhorn". Early builds used 2D and 3D representations of a longhorn bull; later builds included white or glass versions of the Windows flag.

Concepts, presentations, demos and prototypes

 * Earliest concepts (2002, 2003)
 * MSX "Longhorn Days" (2003)
 * Amazon.com demo (PDC 2003)
 * Get Users to Fall in Love With Your Software - Hillel Cooperman's demo from PDC 2003 (video)
 * Business solutions enabled by Longhorn technologies by Carter Maslan (2004, mockups only)
 * Commercial Real Estate (video)
 * Financial Services (video)
 * Healthcare (video)
 * Manufacturing (video)

Implementation of concepts
Twitter user Lucas Brooks (mswin_bat) found that porting the private Milestone 7 Aero theme to a Milestone 5 build like 4017 enables the striped sidebar shown in a demo.

Builds

 * For server builds, see the Windows Server 2008 page.

 Lab guide (Source: Grabberslasher)
 * Lab01: Base (Kernel)
 * Lab02: Networking
 * Lab03: Server
 * Lab04: Management
 * [Lab05:] Main
 * Lab06: Desktop
 * Lab07: IIS/COM+

Milestone 1&2
Planning stage. No builds known.

Milestone 3

 * 3663.0.Lab06_N.020728-1728
 * 3670.0.Lab06_N.020819-1749
 * 3683.0.Lab06_N.020923-1821
 * 3706.0.Lab06_N.021029-1731
 * 3708.0.Lab06_N.021108-1847
 * 3713.0.Lab06_N.021113-1841
 * 3718.0.lab06_N.021119-1730

Milestone 4

 * 4000
 * 4001.0.main.021204-1515
 * 4002.0.Lab06_N(ntvbl06).030108-1926
 * 4005.0.main.030128-1920
 * 4006.0.main.030203-1038
 * 4008.0.main.030219-1933
 * 4011.0.main.030305-2045

Milestone 5

 * 4015.0.main.030328-1500
 * 4015.0.Lab06_n.030403-1706
 * 4017.0.main.030409-0735
 * 4018.0.Lab06_n.030417-1721
 * 4020.0.idx02.030430-2218
 * 4020.0.idx02.030507-1155
 * 4029.0.main.030619-0000
 * 4030.0.main.030626-1414
 * 4031.0.main.030703-0020

Milestone 6

 * 4029.0.Lab06_n.030629-1710
 * 4030.0.Lab06_n.030630-1724
 * 4030.0.Lab06_n.030702-1727
 * 4031.Lab06_n.030707-1834
 * 4032.0.Lab06_n.030710-1709
 * 4033.0.main.030717-1555
 * 4033.0.idx01.030730-1630
 * 4038.0.main.030813-1852
 * 4039.0.Lab06_n.030824-1954
 * 4039.0.Lab06_n.030827-1717
 * 4040.0.Lab04_N.030828-1910
 * 4042.0.main.030905-1800

Milestone 7

 * 4042.0.Lab06_n.030909-1709
 * 4044.0.Lab06_n.030915-1925
 * 4048.0.idx02.030925-1900
 * 4050.0.idx02.030928-0552
 * 4050.0.private/lab06_demo.031018-2015
 * 4050.0.private/lab06_demo.031019-1809
 * 4051.0.idx02.031001-1340
 * 4053.0.main.031022-1720
 * 4067.0.private/lddm_dev_tech(davidmo).040212-1646
 * 4067.0.idx01.040312-1730
 * WinHEC 2004 Aero demo build
 * 4074.0.idx02.040425-1535
 * 4081.0.main.040503-1625
 * 4082.0..main.040510-2230
 * 4083.0.main.040516-1537
 * 4084.0.main.040527-0915
 * 4085.0.main.040603-1817
 * 4085.0.Lab07.040609-2350
 * 4086.0.main.040615-1745
 * 4086.0.lab03_dev.040629-1910
 * 4086.0.lab01_n.040704-2000
 * 4087.0.main.040626-0846
 * 4088.0.Lab02_N.040706-1655
 * 4089.0.private_lab06_dev_ux.040721-1800
 * 4093.0.main.040819-1215
 * 4093.Lab02_N.041002-1235

Development reset

 * See Windows Vista.

BetaArchive forum

 * The Longhorn Kernel-Mode Timebomb
 * Aborted Longhorn concepts/features
 * Windows "Longhorn" features present in Windows Vista
 * ReflectiaX's Longhorn Beta and Demo Files Thread!

Microsoft

 * The Pillars of Longhorn
 * The Pillars of Longhorn: Living La Vida Longhorn (Longhorn Foghorn)
 * Avalon
 * Indigo
 * Introducing Indigo: An Early Look, February 2005 (May 2005 version from the authors' site)
 * Longhorn Developer Center Home: User Experience (Aero)
 * A First Look at Writing and Deploying Apps in the Next Generation of Windows
 * Jim Allchin - The Longhorn Update

Paul Thurrott

 * Paul Thurrott's SuperSite for Windows: The Road to Windows "Longhorn" (last updated 13 November 2002)

Longhorn.ms

 * Aurora & Aero | Microsoft Longhorn
 * Hacking Avalon – 1: Disable it
 * Hacking Avalon – 2: Port it | Microsoft Longhorn
 * Hacking Avalon – 3: Compiling xaml
 * Managed C++ and the Longhorn Shell
 * .NET framework
 * Startpage
 * Help center

Other non-Microsoft

 * UX.Unleaked Grabberslasher's blog that describes several unleaked "Longhorn" builds
 * Jim Allchin’s Mac message: The full text (leading up to the reset)
 * Longhorn Rumors: What's true and what isn't — WinWorld
 * Document Preview : General Windows Support
 * Retro: Windows Longhorn - Nerdshack
 * Code name: Longhorn by John Clyman, PC Mag article
 * Microsoft Shows New Features of Windows Longhorn (PCWorld article from 5 May 2004 about WinHEC 2004)
 * Indigo: The Longhorn Communications Layer (Figure 1)