Cloud Computing Bible

Chapter 4. Understanding Services and Applications by Type

IN THIS CHAPTER

• Learning about different service types

• Creating clouds with Infrastructure as a Service

• Working with Software as a Service

• Developing applications on a Platform as a Service

• Securing cloud transactions with Identity as a Service

This chapter describes some of the different types of cloud computing models, categorized as a set of service models. You may think of cloud computing applications as being composed of a set of layers upon which distributed applications may be built or hosted. These layers include Infrastructure, Platform, and Software. Depending on the type and level of service being offered, a client can build on these layers to create cloud-based applications.

The service models described here—Infrastructure as a Service (IaaS), Software as a Service (SaaS), and Platform as a Service (PaaS)—are useful in categorizing not only cloud computing capabilities, but specific vendor offerings, products, and services. Infrastructure as a Service allows for the creation of virtual computing systems or networks.

Software as a Service represents a hosted application that is universally available over the Internet, usually through a browser. With Software as a Service, the user interacts directly with the hosted software. SaaS may be seen to be an alternative model to that of shrink-wrapped software and may replace much of the boxed software that we buy today.

Platform as a Service is a cloud computing infrastructure ...