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Amazon.com, which hopes to build a huge business renting its massive storage and computing power, used LinuxWorld on Tuesday as a forum to push the idea of building application services on top of someone else's Web infrastructure.

Werner Vogels, chief technology officer for the online retail giant, discussed during his keynote at the open-source software conference in San Francisco how Amazon.com has evolved over the last dozen years into a technology platform for rent, as well as a retailer.

"It's a huge service-oriented architecture," Vogels said of Amazon. "We know everything about developing software as a service."

Amazon.com this month announced that its virtual computing environment called Elastic Compute Cloud, or EC2, had been expanded to allow developers to share and sell software as a service. The company also started early in August a limited beta test of what the company calls its Flexible Payments Service, a set of Web services application programming interfaces for moving money between people or computers.

Vogels listed many reasons why it makes sense to build and offer a Web service on top of someone else's infrastructure. Application service providers, for example, can focus on adding competitive features, and not spending resources on dealing with such complexities as power generators, bandwidth, server capacity and hard disk failures. The latter is a given and can cause a big drop in performance, even though management software can prevent a loss of data. "You will lose about 8% to 10% of your disks per year. Period. It's a given," Vogels said.

Through Amazon, a service provider can rent storage and computing power that scales up or down, depending on demand. Customers are charged only for what they use. Amazon also offers a messaging service, as well as its new payments service. "These services together give you a complete virtualized infrastructure that you can build your business on," Vogels said.

An example of a third-party service currently offered through EC2 is Apatar, an open-source data integration application to help join desktop data with the Web. A user, for example, could turn spreadsheets on their computer into an RSS feed.

Base pricing for the Amazon EC2 computing environment is 10 cents per instance-hour consumed, 10 cents per Gbyte of data in, and 18 cents per Gbyte out, plus storage and request charges.