Understanding Public Cloud “as a Service”
I briefly introduced the core types of cloud services in Chapter 1, “Introduction to
Virtualization and Microsoft Solutions.” Figure 12.1 shows the key types of cloud
services again so that we can review them as they relate to Microsoft Azure. The image
shows the main elements of a service and the boundaries of responsibility for the
different cloud service options.
Figure 12.1 The key types of public cloud services
As you move from on-premises to infrastructure as a service (IaaS) to platform as a
service (PaaS) and finally to software as a service (SaaS), the elements of the solution
that you as an organization are responsible for decrease, until with SaaS there is no
infrastructure management at all. Instead, only basic administration may be required,
such as deciding which accounts should have which capabilities in the service.
IaaS can be thought of as a virtual machine in the cloud. The provider has a virtual
environment, and you purchase virtual machine instances. You then manage the
operating system, the patching, the malware definition updates, the backups, the data,
and the applications within them. Microsoft introduced an IaaS component to
Microsoft Azure in 2012.
PaaS provides a framework in which custom applications can run. Organizations need
to focus only on writing the very best application within the guidelines of the platform
capabilities, and everything else is taken care of. There are no worries about patching
operating systems, updating frameworks, backing up SQL databases, or configuring
high availability. The organization just writes the application and pays for the
resources used. Microsoft Azure is the classic example of a PaaS, and it was the
original focal point for Microsoft Azure.
SaaS is the ultimate in low maintenance. The complete solution is provided by the
vendor. There is nothing to write or maintain by the organization other than
configuring who in the organization should be allowed to use the software. A