The MSDE desktop database technology will not be supported on Windows Vista or Longhorn Server, Microsoft has announced. MSDE (variously called the Microsoft Data Engine or the Microsoft SQL Desktop Engine) is a free version of the SQL Server relational database engine and is designed for use on desktops and low-capacity servers. The announcement means that many software vendors, including Microsoft, that have incorporated MSDE into their applications will need to update those applications to support Vista and Longhorn Server. Furthermore, organizations that want to deploy Vista or Longhorn Server will have to first find and upgrade any MSDE instances and MSDE-dependent applications, potentially a difficult task.

Two versions of MSDE, MSDE 1.0 and 2000, will not be supported on Windows Vista or Longhorn Server. MSDE has been superseded by SQL Server 2005 Express Edition, released in late 2005, and only Express Edition will be supported on Vista and Longhorn Server.

"Mainstream" Doesn't Mean Forward Compatibility

Microsoft says it will not support MSDE on Vista or Longhorn Server because MSDE cannot be automatically updated through Microsoft Update, but problems adapting MSDE to work with Vista's enhanced security features, such as User Account Protection, probably also played a role.

However, the decision is unusual because MSDE 2000 is in the fully supported, or Mainstream Support, phase of its life cycle until Apr. 2008. This highlights an important limitation in Mainstream Support: Products in Mainstream Support are not guaranteed to work with later versions of Windows or other underlying platform software. From Microsoft's perspective, Mainstream Support dictates only how long the company will accept requests to fix problems or bugs and offer for-fee support contracts for the product on the platforms for which it was originally designed. Even under Mainstream Support, Microsoft makes actual product changes and fixes at its sole discretion.

Impact on Developers, IT

Microsoft is not fully testing MSDE on Vista and so is not telling customers what problems they might encounter. In a blog posting announcing the change, Mike Wachal, a program manager on the SQL Express team, said, "We make no claims of any kind about MSDE functionality on Vista" and "I've heard some anecdotal reports that MSDE does not survive the upgrade from Windows XP to Vista. This is all really a moot point since Microsoft will not support MSDE on Vista."

Many software vendors, including Microsoft, have embedded MSDE in applications. These vendors will now have to migrate their applications to use SQL Server 2005 Express Edition rather than MSDE, if they want the applications to work on Vista and Longhorn Server. Microsoft has said it will provide patches for its own applications, although it doesn't now have a comprehensive list of applications that will require patches.

IT managers that want to upgrade to Vista or Longhorn Server must first find all computers with MSDE or MSDE-dependent applications. As the 2003 SQL Slammer worm (which targeted SQL Server and MSDE) demonstrated, this could be a surprisingly large number of systems. Many users were not aware that MSDE could be installed with many of their applications, including some installations of Access and Visio, as well as numerous developer tools. Although Microsoft has not released any specific tools to help find MSDE instances, many security tools, such as the Baseline Security Analyzer, can help identify affected systems.

MSDE can be upgraded in place to SQL Server 2005 Express, but the process is complex and difficult to automate, even using tools such as Systems Management Server (SMS). Furthermore, applications that use MSDE will also need to be updated so that they use the new engine rather than the old one. In the case of internally developed applications, IT managers can update the applications directly, but for Microsoft or third-party applications, they will need to contact their vendor to obtain the necessary patches.

The blog posting can be found at blogs.msdn.com/sqlexpress/archive/2006/08/09/693650.aspx.

Instructions for updating MSDE to SQL Server 2005 Express can be found at www.microsoft.com/technet/prodtechnol/sql/2005/msde2sqlexpress.mspx.

A 2004 list of Microsoft products that use MSDE 2000 (from the time of the Slammer outbreak) can be found at www.microsoft.com/technet/security/bulletin/msdeapps.mspx.