3. Definition
The National Institute of Standards and
Technology (NIST) provides a concise and
specific definition:
Cloud computing is a model for enabling convenient,
on-demand network access to a shared pool of
configurable computing resources (e.g., networks,
servers, storage, applications, and services) that
can be rapidly provisioned and released with
minimal management effort or service provider
interaction.
4. How it works
Utilizes the network as a means to connect user
end point to resources that are centralized in a data
center.
The data center may by accessed via the internet
or a company network, or both.
Allows access from a variety of end points such as
a mobile phone, a PC or a tablet.
Cloud services may be designed to be vendor
agnostic, working equally well with Linux, Mac and
PC platforms.
6. Architecture
Involves multiple components communicating with
each other over application programming
interfaces, usually web services and 3-tier
architecture.
Multiple programs each doing one thing well and
working together over universal interfaces.
Complexity is controlled and the resulting systems
are more manageable than their monolithic
counterparts.
7. The two most significant components of cloud
computing architecture are known as the
front end and the back end.
The front end is the part seen by the client, i.e. the
computer user. This includes the client’s network
and applications used to access the cloud via a
user interface such as a web browser.
The back end of the cloud computing architecture is
the ‘cloud’ itself, comprising various computers,
servers and data storage devices.
9. Key characteristics
Agility improves with users' ability to rapidly and
inexpensively re-provision technological
infrastructure resources.
Application Programming Interface (API)
accessibility to software that enables machines to
interact with cloud software in the same way the
user interface facilitates interaction between
humans and computers.
Cost is claimed to be greatly reduced and in a
public cloud delivery model capital expenditure is
converted to operational expenditure.
10. Key characteristics
Reliability is improved if multiple redundant sites
are used, which makes cloud computing suitable for
business continuity and disaster recovery.
Scalability via dynamic "on-demand" provisioning of
resources on a fine-grained, self-service basis near
real-time.
Performance is monitored, and consistent and
loosely coupled architectures are constructed using
web services as the system interface.
Security could improve due to centralization of
data.
11. Service Models
There are three types of the cloud:
Infrastructure as a Service (IaaS)
Platform as a Service (PaaS)
Software as a Service (SaaS)
14. Why use cloud computing
Website traffic fluctuates.
Visitors expect steady, fast performance regardless.
An infrastructure able to handle peak traffic requires capital
investment.
No matter how big you build it, it still may not be enough.
Having to choose between overspending or under-
provisioning is a classic dilemma.
By deploying your web application in the cloud, you can avoid
this dilemma. You can eliminate the upfront fixed
investment, and still gain access to compute resources to
meet peak loads with on demand scalability, while still
paying only for the compute time you actually use.
