Cloud Computing: History, Service Models, Architecture, Security, and Limitations

CLOUD COMPUTING
Cloud computing refers to an IT (Information
Technology) paradigm which enables ubiquitous
means of entry to communal pools of consignable
system resources and services of high levels which
can be provisioned rapidly with minimal
supervisory efforts, normally over the internet. It
relies on sharing of resources to accomplish
economies of scale and coherence, just like in
public utility.

History of Cloud Computing
Cloud computing began in the early 1960’s with
introduction of RJE (Remote Job Entry) associated
with the then large vendors such as DEC and
IBM. Full-time-sharing solutions were already in
the industry by mid-1970’s on platforms like
Cambridge CTSS and Multics (on GE hardware).
Telecommunication companies fanned into this
industry in the 1990’s.

Telecommunication companies that offered
predominantly dedicated point-to-point
circuits of data, started offering VPN (Virtual
Private Network) services with tantamount
quality of service, though at lower costs.
Through switching traffic as deemed fit in
balancing server use, they could put to use
most network bandwidth most effectively.They started using cloud symbol denoting demarcation point between what
consumers were responsible for, and what the provider was susceptive to.

SERVICE MODELS
On the left is a breakdown of cloud computing
service models systematized as layers forming
a stack. Providers of cloud-computing offer
their services depending on the models, which
are three according to international standards
(NIST): PaaS (Platform as a Service), SaaS
(Software as a Service) and IaaS
(Infrastructure as a service).