Which of the following examples best describes the SaaS service model? (Select the best answer.)
A.
A company moves all companywide policy documents to an Internetbased virtual file system hosted by a
service provider.
B.
A company hires a service provider to deliver cloudbased processing and storage that will house multiple
virtual hosts configured in a variety of ways.
C.
A company licenses an office suite, including email service, that is delivered to the end user through a web
browser.
D.
A company obtains a subscription to use a service provider’s infrastructure, programming tools, and
programming languages to develop and serve cloudbased applications.
Explanation:
A company that licenses an office suite, including email service, that is delivered to the end user through a web
browser is an example of the Software as a Service (SaaS) service model. The National Institute of Standards
and Technology (NIST) defines three service models in its definition of cloud computing: SaaS, Infrastructure
as a Service (IaaS), and Platform as a Service (PaaS).
The SaaS service model enables its consumer to access applications running in the cloud infrastructure but
does not enable the consumer to manage the cloud infrastructure or the configuration of the provided
applications. A company that licenses a service provider’s office suite and email service that is delivered to end
users through a web browser is using SaaS. SaaS providers use an Internetenabled licensing function, a
streaming service, or a web application to provide end users with software that they might otherwise install and
activate locally. Webbased email clients, such as Gmail and Outlook.com, are examples of SaaS.
The PaaS service model provides its consumer with a bit more freedom than the SaaS model by enabling the
consumer to install and possibly configure providersupported applications in the cloud infrastructure. A
company that uses a service provider’s infrastructure, programming tools, and programming languages to
develop and serve cloudbased applications is using PaaS. PaaS enables a consumer to use the service
provider’s development tools or Application Programmer Interface (API) to develop and deploy specific
cloudbased applications or services. Another example of PaaS might be using a third party’s MySQL database
and Apache services to build a cloudbased customer relationship management (CRM) platform.
The IaaS service model provides the greatest degree of freedom by enabling its consumer to provision
processing, memory, storage, and network resources within the cloud infrastructure. The IaaS service model
also enables its consumer to install applications, including operating systems (OSs) and custom applications.
However, with IaaS, the cloud infrastructure remains in control of the service provider. A company that hires a
service provider to deliver cloudbased processing and storage that will house multiple physical or virtual hosts
configured in a variety of ways is using IaaS. For example, a company that wanted to establish a web server
farm by configuring multiple Linux Apache MySQL PHP (LAMP) servers could save hardware costs by
virtualizing the farm and using a provider’s cloud service to deliver the physical infrastructure and bandwidth for
the virtual farm. Control over the OS, software, and server configuration would remain the responsibility of theorganization, whereas the physical infrastructure and bandwidth would be the responsibility of the service
provider.
A company that moves all companywide policy documents to an Internetbased virtual file system hosted by a
third party is using cloud storage. Cloud storage is a term used to describe the use of a service provider’s
virtual file system as a document or file repository. Cloud storage enables an organization to conserve storage
space on a local network. However, cloud storage is also a security risk in that the organization might not have
ultimate control over who can access the files.NIST: Special Publication 800145: The NIST Definition of Cloud Computing (PDF)