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IJRREST: International Journal of Research Review in Engineering Science and Technology (ISSN 2278- 6643) | Volume-1 Issue-3, December 2012
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Cloud Computing: A Promising Expertise *Zatin Gupta, **Ashish Gupta, ***Saurabh Agrawal
*Assistant Professor, RKGIT, Ghaziabad, UP, India, [email protected]
**Assistant Professor, RPIIT, Karnal, Haryana, India, [email protected]
***M.Tech.(CSE) Scholar, RTU, Rajasthan, India, [email protected]
Abstract: “Cloud” computing – a relatively recent
term, defines the paths ahead in computer science
world. Being built on decades of research it
utilizes all recent achievements in virtualization,
distributed computing, utility computing, and
networking. It implies a service oriented
architecture through offering software’s and
platforms as services, reduced information
technology overhead for the end-user, great
flexibility, reduced total cost of ownership, on
demand services and many other things. This
paper is a brief survey based of readings on
“cloud” computing and it tries to address, related
research topics, challenges ahead and possible
applications. The boom in cloud computing over
the past few years has led to a situation that is
common to many innovations and new
technologies: many have heard of it, but far fewer
actually understand what it is and, more
importantly, how it can benefit them.
Keywords: Cloud computing, PaaS, SaaS, IaaS
1. INTRODUCTION
Cloud computing is the next generation in
computation. Maybe Clouds can save the world;
possibly people can have everything they need on the
cloud.
Cloud Computing,” to put it simply, means “Internet
Computing.” The Internet is commonly visualized as
clouds; hence the term “cloud computing” for
computation done through the Internet. Cloud
computing is the next natural step in the evolution of
on-demand information technology services and
products.
With Cloud Computing users can access database
resources via the Internet from anywhere, for as long
as they need. Besides, databases in cloud are very
dynamic and scalable. Cloud computing is unlike
grid computing, utility computing, or autonomic
computing.
In fact, it is a very independent platform in terms of
Computing. The best example of cloud is Google
Apps where any application can be accessed using a
browser and it can be deployed on thousands of
computer through the Internet.
Figure1: Cloud Computing
Cloud computing is a very specific type of
computing that has very specific benefits. But it has
specific negatives as well. And it does not serve the
needs of real businesses to hear only the hype about
cloud computing – both positive and negative. One
thing that is hoped to be accomplished with this paper
is not only a clear picture of what the cloud does
extremely well.
a) What is Cloud Computing?
Cloud computing is a subscription based on -demand
service where by resources, infrastructure, platforms
and software’s are delivered “as a service” to the
customers over the “internet cloud” via virtual shared
servers. The location of physical resources and
devices being accessed are typically not known to the
end user. Users can access these services without
having knowledge of how to manage the resources
needed to run their processes.
Email was probably the first service on the “cloud”.
To access your Email account, you just required an
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internet connection and it can be accessed anywhere
as it is not housed on your personal computer.
Some generic examples include:
• Amazon’s Elastic Computing Cloud (EC2) offering
computational services that enable people to use CPU
cycles without buying more computers
• Storage services such as those provided by
Amazon’s Simple Storage Service (S3)
b) Architecture of Cloud computing:
Cloud computing architecture works through two
components:
“Front end” and “Back end”. At the front end,
client’s device and some applications are needed to
access the cloud computing system, whereas this
whole cloud computing system, a group of clouds
(computer machines, data storage system, and
servers) is available at the backend. A “Central
server” is used to administer the whole system along
with monitoring of clients demand and traffic to
ensure smooth functioning of system and
“Middleware” is required to provide communication
among the computers on the network. Cloud
computing systems also must have a copy of all its
clients’ data to restore the service which may arise
due to a device breakdown.
Cloud computing can be visualized as a pyramid
consisting of three sections:
Cloud Application: This is the apex of the cloud
pyramid, where applications are run and interacted
with via a web browser, hosted desktop or remote
client. A hallmark of commercial cloud computing
applications is that users never need to purchase
expensive software licenses themselves. Instead, the
cost is incorporated into the subscription fee. A cloud
application eliminates the need to install and run the
application on the customer's own computer, thus
removing the burden of software maintenance,
ongoing operation and support.
Cloud Platform: The middle layer of the cloud
pyramid, which provides a computing platform or
framework as a service, a cloud computing platform
dynamically provisions, configures, reconfigures and
de-provisions servers as needed to cope with
increases or decreases in demand. This in reality is a
distributed computing model, where many services
pull together to deliver an application or
infrastructure request.
Cloud Infrastructure: The foundation of the cloud
pyramid is the delivery of IT infrastructure through
virtualization. Virtualization allows the splitting of a
single physical piece of hardware into independent,
self governed environments, which can be scaled in
terms of CPU, RAM, Disk and other elements. The
infrastructure includes servers, networks and other
hardware appliances delivered as Infrastructure “Web
Services”, “farms” or "cloud centers". These are then
interlinked with others for resilience and additional
capacity.
2. DEPLOYMENT MODELS
a) Public Cloud: Cloud’s servers, storage
system and networks are shared among general
public through third party. They deliver superior
economies of scale to customers, as the infrastructure
costs are spread among a mix of users, giving each
individual client an attractive low-cost, “Pay-as-you-
go” model. There are limited service providers like
Microsoft, Google etc.
Figure 2: Public Cloud Example
Public cloud can be much larger than company’s
private cloud as it provides the ability to scale
seamlessly on demand & thus shifting the whole risk
from the enterprise to the cloud provider.
b) Private cloud: Private clouds are meant for
organizations that wants an exclusive control over
data, security & quality of Service. Private clouds
may be deployed in an enterprise datacenter or at a
collocation facility. Private Clouds can be built and
managed by Company’s own IT organizations or by a
Cloud Provider. There are two variations to a private
cloud:
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Figure 3: Private Cloud Example
- Internally hosted Private Cloud: These clouds
are hosted within a Company’s enterprise datacenter
with the help of experts to install, configure &
operate the infrastructure. This model provides a
more standardized process and protection, but is
limited in aspects of size and scalability.
- Externally hosted Private Cloud: This type of
private cloud is hosted externally with a cloud
provider, where the provider facilitates an exclusive
cloud environment.
c) Hybrid Cloud: Hybrid Cloud is a
combination of two or more clouds (private, public or
community) that remain unique entities but are bound
together offering the benefits of multiple deployment
models. The Hybrid cloud environment is capable of
providing on-demand, externally provisioned scale.
Figure 4: Hybrid Cloud Example
Combining private & public cloud resources helps to
maintain the quality of service even in rapid
workload fluctuations & to handle planned workload
spikes. Hybrid Clouds introduce the complexity of
determining how to distribute applications across
both a public and private cloud.
d) Community Cloud: A community cloud is
shared among two or more organizations from a
specific community that have similar cloud
requirements (security, compliance, jurisdiction etc.).
It can be managed either internally or by a third party
and hosted internally or externally. It is more
economical than private clouds in comparison to
public clouds because costs are spread over fewer
users.
3. ARCHITECTURE OF CLOUD
COMPUTING
a) Software as a Service (SaaS): In this model, a
complete application is offered to the customer, as a
service on demand. A single instance of the service
runs on the cloud & multiple end users are serviced.
In this model, cloud provider deploys application
software in the cloud and cloud users access the
software from cloud clients. It frees the cloud users
from managing the cloud infrastructure and platform.
What makes a cloud application different from other
applications is its elasticity. This can be achieved by
cloning tasks onto multiple virtual machines at run-
time to meet the changing work demand. As the no.
of user’s increases, Load balancers are used to
distribute the work over the set of virtual machines.
This process is transparent to the cloud user who sees
only a single access point. To accommodate a large
number of cloud users, cloud applications can be
multitenant, that is, any machine serves more than
one cloud user organization.
The most widely known examples of SaaS are
Google, Salesforce, Microsoft, Zoho, etc. It is
commonly referred to as desktop as a service,
business process as a service, Test Environment as a
Service, communication as a service.
b) Platform as a Service (PaaS): In PaaS model,
cloud provider provides a developing environment or
a computing platform as a service where a user can
build other higher-level services. PaaS depends on
two perspectives:
Producing PaaS: It might produce a platform by
integrating an operating system, programming
language execution environment, web server,
middleware which is provided to a customer as a
service such as LAMP platform (Linux, Apache,
MySql and PHP), restricted J2EE, Ruby etc.
Google’s App Engine, Force.com, etc are some of the
popular PaaS examples.
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Using PaaS: Here customer interacts with the
encapsulated environment provided by the producers
through an API. Now user can develop & run their
software solutions without focusing on the cost &
complexity of buying & managing the hardware &
software. For example, a content switch appliance
would have all of its component software hidden
from the customer & only an API or GUI for
configuring and deploying the services provided to
them.
c) Infrastructure as a Service (IaaS): In IaaS,
cloud provider’s delivers basic storage and compute
capabilities as services over the network. IaaS make
available these resources (servers, load balancers,
firewalls, switches, routers) on demand from their
large pools installed in data centers. It offers IP
addresses for Local Area Networks.
In this, cloud users install and maintain the operating
system and application software to deploy their
applications. IaaS is a ‘utility-basis ‘computing
service means cost will incur as resources are
consumed.
4. CLOUD COMPUTING BENEFITS
a) Reduce Run time and Response time: It reduces
run time and response time. For instance, for running
batch jobs, cloud computing uses 1000 servers to
accomplish a task in 1/1000 the time that a single
server would require and virtual machines to
optimize response time.
b) Minimizes Infrastructure risk: Using Cloud
Computing infrastructure, cloud users become free
from the risk inherent in purchasing physical servers
as now it is the cloud provider’s risk for purchasing
too much or too little infrastructure.
c) Reduced Cost: As it is subscription-based service,
lowering maintenance as infrastructure is not
purchased, initial expense and recurring expenses are
much lower than traditional computing, it is
considered as lower cost Cloud technology.
d) Increased Storage: As massive storage is
provided by cloud computing infrastructure, large
volumes of data and sudden workload spikes can be
managed effectively & efficiently.
e) More Mobility: Employees can access
information where ever they are, rather than having
to remain at their desks.
5. CLOUD COMPUTING CHALLENGES
Despite its growing influence, there are some
concerns regarding cloud computing:
a) Security: Achieving high quality data security is
crucial as data it is stored in the cloud’s Server
storage system.
b) Reliance on third party: Control over own data is
lost in the hands of a “difficult-to-trust” provider.
c) Cost of transition: It is not feasible always to
move from the existing architecture of our own data
center to the architecture of the cloud.
d) Uncertainty of benefits: One can’t be assured for
having long term benefits of cloud computing.
6. CONCLUSION
After so many years, Cloud Computing today is the
beginning of “network based computing” over
Internet in force. It is the technology of the decade
and is the enabling element of two totally new
computing models, the Client-Cloud computing and
the Terminal-Cloud computing. These new models
would create whole generations of applications and
business. Our prediction is that it is the beginning to
the end of the dominance of desktop computing such
as that with the Windows. It is also the beginning of
a new Internet based service economy: the Internet
centric, Web based, on demand, Cloud applications
and computing economy.
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