Software as a Service
the third category, is the largest and most mature part of the cloud. It’s an application or suite of applications that resides in the cloud instead of on a user’s hard drive or in a data center. One of the earliest SaaS successes was Salesforce.com’s customer relationship management software, which provided an alternative to on-premise CRM systems when it was launched, in 2000. More recently, productivity and collaboration software—spreadsheets, word processing programs, and so on—has moved into the cloud with Google Apps, Microsoft Office 365, and other similar offerings.Cloud offerings share a few similarities across these three categories. First, customers rent them instead of buying them, shifting IT from a capital expense to an operating expense. Second, vendors are responsible for everything “beneath the hood”—all the maintenance, administration, capacity planning, troubleshooting, and backups. And finally, it’s usually fast and easy to get more from the cloud—more storage from an IaaS vendor, the ability to handle more PaaS projects, or more seats for users of a SaaS application.Some large organizations are planning to build “private clouds” that they will own and maintain. These are essentially data centers that use many of the cloud’s technologies. Private clouds hold the promise of offering all the advantages of the public cloud while addressing security and regulatory concerns. However, I’m skeptical. The scale economies of public cloud companies lead to great cost decreases over time, and because their environments are intensely competitive, those decreases will surely be reflected in their prices. I doubt that most private clouds will be able to keep up.