Microsoft at the end of the month will unveil its "Cloud OS," the secretive Ray Ozzie project that provides a virtual Windows operating system platform for the rapid development, deployment, and maintenance of Internet services and applications.

Microsoft will unveil details later this month at its Professional Developers Conference (PDC) and show developers the APIs and plumbing services provided by a utility computing platform code-named Red Dog.

In essence, it is an application development and execution platform that lives on the Internet. Red Dog is similar to Amazon's Elastic Compute Cloud (EC2) and Google's App Engine, both cloud-based application platforms.

Microsoft also plans to detail the next version of its .Net Framework and improvements to its Web application server that will make it a platform for hosting composite and Web 2.0 applications.

With Red Dog, developers write their applications to take advantage of cloud operating system services much like they do to exploit services on desktop and server operating systems.

Microsoft CEO Steve Ballmer told IT managers at a meeting in London last week that the official name and details of something he called "cloud OS" would see their debut at PDC.

Ozzie and his cloud infrastructure services team at Microsoft have quietly been working for the past few years on what has come to be known as the Red Dog project.

The platform, according to Ballmer, will be in simple terms Windows Server for the cloud and will provide such functions as scaling and server management. He told the IT managers the first version will work with Microsoft's data center but future versions could be used in other data centers.

"If you are a developer writing an application on the Microsoft platform, what is new that you will be able to do or to use that you can't do today – those are the questions that should be answered at PDC," says Matt Rosoff, an analyst with the independent research firm Directions on Microsoft.

Ozzie said in July the services platform, as he called it at the time, would provide users with "a new kind of system designed for massive scale-outs, running on large redundant arrays of inexpensive commodity servers in the cloud."

For software on the back end, he said, programs would be spread out across hundreds or even thousands of PCs running in a cloud-based data center that appears like one data center to the programmer but is actually spread around the world.