Microsoft has fleshed out details of the Longhorn version of its Windows operating system, and unveiled its next-generation Windows programming model, named WinFX.

Microsoft said WinFX, a development of the .Net Framework's programming model, could increase developer productivity and application security and reliability.

Speaking at the company's Professional Developers Conference 2003, Microsoft chairman and chief software architect, Bill Gates, said: "Continuing hardware advances, powerful tools and the potential of anything on the internet to become a building block all make it a great time to do pioneering work."

Meanwhile Jim Allchin, group vice president of the company's platforms group, gave the audience a sneak preview of the major areas of platform improvements aimed at developers in the forthcoming Windows Longhorn release.

Allchin claimed that Longhorn will build on the security in Windows XP to protect against malicious exploits, as well as introduce "new security improvements at the architecture level that developers can take advantage of to help extend security across applications and services".

He said Windows presentation technologies, code-named "Avalon", which form the graphics subsystem in Longhorn, and a foundation of the operating system's shell, will offer developers a unified architecture for user interface, documents and media.

Microsoft also showed off the revamped Windows communications technologies, code-named 'Indigo', which allows systems to be built around the web services architecture.