Microsoft has launched web-based versions of two of its enterprise software offerings.

The first beta versions of Exchange Online and SharePoint Online will allow businesses to use hosted services for email, messaging, videoconferencing and shared workspace sessions.

The new applications are part of a campaign to expand Microsoft Online Services to small and medium sized businesses. The service had been limited to businesses able to register more than 5,000 users.

Microsoft Online Services will be opened up to businesses of all sizes on a per-user subscription fee when it opens to the public later this year.

The hosted offerings are part of Microsoft's "software plus services" in which the company uses web services to complement its packaged software.

Vendors such as Google and Salesforce have long pushed 'software-as-a-service' products in which locally installed applications are completely replaced by a web-based service.

"The combination of software plus services gives customers advanced choice and flexibility in how they access and manage software," said Microsoft chairman Bill Gates.

"With Microsoft Online Services, businesses can deploy software as a subscription service from servers they manage on-site, or a combination of the two, depending on their specific needs."

Gates sees being able to combine services with software becoming a widespread practice for Microsoft.

"In the future, customers and partners should expect to see this kind of choice and flexibility for all Microsoft software and server products," he said.