Characteristics and Service Models*
Cloud computing means many things to many people. The Internet, its protocols, and its standards are the technical basis for cloud computing, but the discussion must include the entire organization. In many ways, cloud computing is a technological occurrence, but as emphasized in Chapter 1, cloud computing is a new way of delivering IS and IT. Our historical review showed that cloud computing is the evolutionary product and convergence of many technologies, including the Internet and its growth. In this chapter we will discuss an overview of the first two dimensions of cloud computing: the essential characteristics and the service models. The third dimension, the deployment models, will be covered in Chapter 3.
The plain old telephone system (POTS) has been depicted as a cloud for many years because a person would pick up the phone and dial but not know what route the call would take to its destination. The Internet has the same quality: a user enters a web address without knowing what route the data will follow from the user's desktop computer to the server being contacted. This phenomenon is the basis for representing the Internet as a cloud symbol. The next evolutionary step, cloud computing, moves services from the data center, desktop, or other on-premises computers to a cloud. As in POTS, when things are moved to a cloud, where things reside and how connections are handled are unknown to the user.
The basic architecture and other ...