Three Cloud service Models in a cloud landscape
Infrastructure as a Service (IaaS)
·
This
model puts together infrastructures demanded by users—namely servers, storage,
networks, and the data center fabric.
·
The
user can deploy and run on multiple VMs running the guest OS on specific applications.
·
The
user does not manage or control the underlying cloud infrastructure but can
specify when to request and release the needed
resources.
Platform as a Service (PaaS)
·
This
model enables the user to deploy user-built applications onto a virtualized
cloud platform. PaaS includes middleware, databases, development tools, and
some runtime support such as Web
·
2.0
and Java.
·
The
platform includes both hardware and software integrated with specific
programming interfaces.
·
The
provider supplies the API and software tools (e.g., Java, Python, Web 2.0,
.NET). The user is freed from managing the cloud infrastructure.
Software as a Service (SaaS)
·
This refers to
browser-initiated application software over thousands of paid cloud customers.
The SaaS model applies to business processes, industrial applications, consumer
relationship management (CRM), enterprise resources planning (ERP), human
resources (HR), and collaborative applications. On the customer side, there is
no upfront investment in servers or software licensing. On the provider side,
costs are rather low, compared with conventional hosting of user applications.
Figure 1.4 The Cloud Landscape in an application
Internet clouds
offer four deployment modes: private, public, managed, and hybrid. These modes
demand different levels of security implications. The different SLAs imply that
the security responsibility is shared among all the cloud providers, the cloud
resource consumers, and the third-party cloud-enabled software providers. The advantages of cloud computing have been advocated by many IT experts, industry
leaders, and computer science researchers.
