On-demand business software vendor Salesforce is expected on Monday to announce Force.com Sites, an offering that lets customers create and run Web sites on Salesforce's cloud infrastructure.

"Customers have been telling us they want to run their entire business in our cloud," said Kendall Collins, senior vice president of product marketing for Salesforce.

Salesforce is also wagering that customers who have already created custom applications with its Force.com development platform might want to repurpose the programs for external use.

For example, a company could use an internal recruiting application for a public jobs portal by building a new Web front end for it with Salesforce's Visualforce tools. Customers would then register a Force.com domain name and publish the site on Salesforce's system.

"We think the primary target is our existing customers. They are going to love this," Collins said.

Force.com Sites is now in developer preview and will be generally available in 2009 -- but Salesforce isn't saying what time of year.

Salesforce believes it is prepared to handle the demands of even large-scale e-commerce Web sites, should customers build them, and is not planning to expand its infrastructure at this time, according to Collins.

"Our architecture is extremely solid for this level of scale," he said. "We think it can handle the capacity, and we're very, very confident on that front."

However, Salesforce is "going to learn a lot" in the next months as the developer preview unfolds, he said. "We're going to turn the faucet on slowly and look at that data."

Salesforce is using page views to determine developer preview pricing. A Group Edition Salesforce subscription includes up to 50,000 monthly page views for a Force.com Site, while on the high end, an Unlimited Edition subscription comes with 1 million monthly views.

When those levels are exceeded, charges kick in at US$1,000 per month for up to 1 million more monthly views, or $3,000 a month for up to 5 million additional views per month, no matter which Salesforce edition a customer has.

But don't expect to launch the next YouTube on Salesforce's system. "I expect that we would do some level of limiting on bandwidth and storage," Collins said. Those details remain to be worked out, he said.