Microsoft on Wednesday laid out its server road map, outlining a series of releases including Longhorn Server, the next major OS edition, targeted to arrive in 2007.

Among the features of Longhorn Server will be support for Indigo, Microsoft's new Web services architecture, as well as improved manageability and support for dynamic partitioning and other features designed to enable Windows "mainframes," said Bob Muglia, the senior vice president in charge of Windows Server development.

Plans for Longhorn Server had been an on-again, off-again proposition for some time. Since late last year, the company has said there would be a server version, but until now has said little about what it would contain. The new timetable is an attempt by Microsoft to clarify its plans so that corporate buyers know what to expect. "Our expectation is that we will ship Longhorn Server in 2007," Muglia said.

Muglia also said Microsoft has slated both a service pack and an update for Longhorn. "We are thinking about an update release to Longhorn that will come in the 2009 time frame; 2008 will probably be the service pack, 2009 will be the update release."

In Microsoft parlance, a service pack is a bug-fix release that's free to customers. An update is typically a more extensive refresh of Windows that Microsoft sells. "It's, effectively, a new release of the server," Muglia said. He said customers under Microsoft's Software Assurance licensing program will receive the update at no additional cost.

The software maker said last week the client and server versions of Longhorn are being developed in parallel, but added later that the additional testing needed for server software would cause that version to lag behind its desktop counterpart. Microsoft has a goal of shipping Longhorn desktop by mid-2006.

Microsoft also outlined more details on an interim server release, code-named R2 and due next year. As earlier reported, the update will include new security technology designed to quarantine new machines as they come onto a network. The update will also include a cross-company identity management scheme, previously code-named Trustbridge. Built-in Windows Rights Management Services are designed to offer e-mail and document-level protection.

Many Microsoft customers have been reluctant to update their server installations and have remained on Windows NT 4.0, now more than eight years old. Muglia said he expects many of those customers to upgrade to Windows Server 2003 this year and that about 20 percent of the overall Windows Server installed base would probably remain on Windows NT 4.0 by year's end.

Muglia said the company is moving to a system in which it plans major server releases every four years, along with "updates" every two years.

Copyright © 2009 CBS Interactive, a CBS Company. All Rights Reserved.
ZDNET is a registered service mark of CBS Interactive. ZDNET Logo is a service mark of CBS Interactive.