WHAT’S IN THIS CHAPTER?
There is so much hype around cloud computing that it is often difficult to get a clear sense of what anyone means by those words. Is it just virtualization? Is it Software-as-a-Service (SaaS), such as Microsoft’s Office 365 and Salesforce.com? Or is it the ability to get a virtual machine instantly from Amazon Web Services (AWS) or Azure? And what about online storage such as Dropbox?
The reality is that cloud computing refers to all of these things just described and more. The National Institute of Standards and Technology (NIST) has come up with an “official” definition based upon five key components: on-demand self-service, broad network access, pooled resources, elasticity, and metered service. In general, these characteristics may be provided in several different models. These models help sort out the confusion and hype. In fact, these can be thought of as layers in a stack, with each layer being built on top of the previous one (see Figure 1.1).
In Figure 1.1, “Manually Provisioned Infrastructure” represents the traditional method of building your information technology infrastructure—this ...