Microsoft has unveiled its platform for cloud-based computing and detailed how developers can build applications for it based on existing tools, while companies will be able to quickly deploy scalable systems.

Called Windows Azure, the platform forms a third tier in computing architecture above desktop PCs and enterprise network domains, according to Microsoft chief software architect Ray Ozzie.

Speaking at the firm's Professional Developer Conference in Los Angeles, Ozzie said that Azure is not yet ready for commercial deployment, but that the firm is using it internally and working with some customers to build out the platform.

Azure itself is a scalable hosting environment for developers to deploy applications in a cloud infrastructure owned and operated by Microsoft. When available, pricing will be metered, based on a customer's resource consumption and the service level required, Ozzie said.

The platform is designed to go beyond the inward-facing scope of most enterprise IT infrastructure, according to Ozzie, and allow it to reach out over the web.

"We're setting the stage for the next 50 years of computing," he said.

Amitabh Srivastava, Microsoft's corporate vice president of Cloud Infrastructure Services, explained that Azure offers scalable hosting with automatic service management, but that developers can still use existing tools to code for it.

"It leverages Microsoft's current tools, such as Visual Studio, and operates with both managed and native code," he said.

Third-party applications like Eclipse and PHP can also easily operate with Microsoft's environment, he added.

Bob Muglia, senior vice president of Microsoft's server and tools business, detailed how Microsoft is working to provide federated identity services to secure access to cloud-based resources.

Using a Microsoft federation gateway, online services will be able to link back to a company's Active Directory infrastructure to verify the identity of a user, he said. Using this, workers need not sign in to online services so long as they are already logged into their corporate domain.

A service bus will also let companies connect on-premises systems securely to the cloud.

"We're seeing that customers will still want to have on-premises systems, but will start to take advantage of cloud services," Muglia said.

"The idea is that you can take advantage of the vast computing power available in the cloud to enable lower-cost deployment of applications that operate in a global environment," he added.

Going forward, this is how Microsoft expects to deliver business software, the company said.

"In future, all our business-class software will be delivered as an online solution," said Dave Thompson, Microsoft's corporate vice president for Online.

Thompson explained how an online version of Exchange will be able to use web services to accept meeting requests, notify users, and synchronise with a company's on-premises Exchange server.