Cloudware Basics - Guide to Cloud Computing for Business and Technology Managers - page 266

the SaaS infrastructure performs any management tasks needed (such as
allocation of additional storage) to support the changed configuration. SaaS
platforms are targeted toward users who want to use the application with-
out any software installation (in fact, the motto of Salesforce.com, one of the
prominent SaaS vendors, is “No Software”). However, for advanced usage,
some small amount of programming or scripting may be necessary to cus-
tomize the application for usage by the business (e.g., adding additional
fields to customer data). In fact, SaaS platforms like Salesforce.com allow
many of these customizations to be performed without programming but
by specifying business rules that are simple enough for nonprogrammers
to implement. Prominent SaaS applications include Salesforce.com for
CRM, Google Docs for document sharing, and Web e-mail systems like
Gmail, Hotmail, and Yahoo! Mail. IT vendors such as HP and IBM also sell
systems that can be configured to set up SaaS in a private cloud; SAP, for
example, can be used as an SaaS offering inside an enterprise.
Table 13.3 presents a comparison of the three cloud delivery models.
13.4 Cloud Deployment Models
13.4.1 Private Clouds
A private cloud has an exclusive purpose for a particular organization. The
cloud resources may be located on or off premise and could be owned and
managed by the consuming organization or a third party. This may be an
example of an organization who has decided to adopt the infrastructure
cost-saving potential of a virtualized architecture on top of existing hard-
ware. The organization feels unable to remotely host their data, so they are
looking to the cloud to improve their resource utilization and automate the
management of such resources. Alternatively, an organization may wish to
extend its current IT capability by using an exclusive, private cloud that is
remotely accessible and provisioned by a third party. Such an organization
may feel uncomfortable with their data being held alongside a potential com-
petitor's data in the multitenancy model.
13.4.2 Public Clouds
A public cloud, as its name implies, is available to the general public and
is managed by an organization. The organization may be a business (such
as Google), academic, or a governmental department. The cloud computing
provider owns and manages the cloud infrastructure. The existence of many
different consumers within one cloud architecture is referred to as a mult-
itenancy model.