Microsoft\u00a0on Monday used its annual Professional Developers Conference in Los Angeles to uncover for the first time its Longhorn operating system, which officials said would be the biggest release of this decade.Bill Gates, Microsoft\u2019s chief software architect, said the much-hyped Longhorn would foster a whole new level of computing defined by security, Web services and managed code. Gates said the opportunities for developers would be stronger in the next decade than at any time in history.Gates was joined by Jim Allchin, group vice president of the platforms group at Microsoft, in a three-hour presentation on the inner workings of Longhorn. The presentation was designed as a visual guide to show off the Longhorn user interface and programming capabilities that have been the subject of speculation in the press.\u201cThe theme today is to get the platform together,\u201d said Gates. \u201cClearly we are at the beginning of [Longhorn] and we need your feedback,\u201d he told the roughly 8,000 attendees. \u201cThis is the biggest release of the decade, the biggest since Windows 95.\u201dGates focused on the client and paid little attention to plans for a server version of the operating system other than to say the Longhorn \u201cwave\u201d of products would include new versions of the client, server and Office. He did not mention any ship dates other than to say PCs in 2006 would have the power and storage needs to support Longhorn\u2019s new presentation system called Avalon; a file system called WinFS; Indigo, a Web services communication bus built into the OS; and WinFX, the new programming model to succeed Win32.Gates also highlighted what he called the fundamentals of Longhorn, basically the needed security such as personal firewalls and patch management systems to lock down Longhorn and make it easier to manage.He also singled out WinFS as \u201cthe holy grail for me.\u201d\u201cSome of you have heard me talk about unified storage for 10 years,\u201d he joked, adding that Longhorn would be the realization of his dream. WinFS will allow users to search for data across the local system, the network and Web services. It is designed to break data away from individual applications so that it can be stored in one central place and shared universally at the platform level. For example, contact and calendar information could be integrated with any number of applications.WinFS, in combination with Indigo, will also play a key role in enabling applications to securely communicate using a set of Web services protocols Microsoft is developing along with IBM, including WS-Security and WS-Reliable Messaging.Allchin then laid out challenges for Longhorn including deployment, reliability, performance and security. He introduced an application installation technology called Click Once and said he was aiming to build a Windows OS that required no reboots.He said Longhorn will have what amounts to a flight data recorder to track what happens in the OS and that security would be a top priority, an area that Microsoft has been working on for years with limited success.Allchin also highlighted Avalon, the presentation subsystem of Longhorn. \u201cIn Avalon we\u2019ll have a unified presentation model for Windows applications, Web applications and media, graphics and animation.\u201dAllchin introduced a new markup language Microsoft has developed called the Extensible\u00a0 Application Markup Language that can be used to build applications in a \u201cdeclarative\u201d way where coding and content can be separated.He, however, tempered his excitement by telling attendees that the preview code of Longhorn that was passed out at the show will still show a lot of warts and that the performance is not good, but he said it was a call to arms.Allchin said the first beta of Longhorn would be available in the first half of 2004.