Demystifying Cloud Computing

In 1960, John McCarthy predicted that someday computing would be organized as

a public utility. And then, in the early 90s, the term 'Grid computing' was

coined by Ian Foster, which talked about technologies that would make computing

power available 'on demand' to consumers. Now, both these statements suddenly

make sense when we hear the word cloud computing and the technologies that have

made it a reality.

Just about every organization today is interested in using cloud computing,

but doesn't know how. Without knowing, it's impossible to make an informed

decision about how to move to it. Simply put, cloud computing is a set of

technologies that allows computing applications and data to be exposed as a set

of services from a pool of underlying resources. The user doesn't have to worry

about the technologies in the pool. This is similar to running an electrical or

electronic device by plugging it to a wall socket. You don't have to worry about

how the power is generated in the power plant. You just want the right voltage

to be made available so that you can power your device and use your device.

Similarly, in Cloud Computing, users simply focus on the services they would

like to use, and not worry about how to implement the software that provides

these services. Even the IT staff that provides these services can easily pull

out the resources required by the users from this pool of resources, and put it

back when the services have been consumed.

A typical cloud computing model.

The foundation of cloud computing comprises of data centers (servers,

storage, networking), the business applications and middleware, virtualization

software and of course operating systems. This foundation provides all the

applications to the users on a 'pay as you go' basis. So the entire workload

shifts to the cloud, i.e. local computers are not burdened with running hundreds

of applications anymore. All that users need is a system interface software,

like a simple web browser to be run on their side.

The three different types of clouds & the relationship amongst them

The benefits



The promise of cloud computing is to provide all that most organizations

have been wanting for years, but haven't been able to achieve.

Scalability: Cloud computing allows an organization to scale up or down their

IT requirements quickly and efficiently, without hampering productivity. It cuts

down the time involved in buying & setting up additional hardware, software &

other necessary resources everytime a new service is required.

Lower infrastructure cost: Pay as you go is the mantra of cloud computing.

You pay only for the duration that you use the service for. This helps cut down

unnecessary capital expenditure. Since the resources can be pulled out and

restored dynamically, a lot of cost related to maintenance, administration, etc

is reduced.

Better utilization: As the IT infrastructure is nothing but a pool of

resources, it reduces wastage and improves resource utilization. It also cuts

down the downtime.

Cloud deployment models



Most of the time, the term cloud computing is confused with the Internet

cloud. It's very important to understand this difference if you want to be able

to use the cloud more effectively. There are basically three types of

cloud-public, private, and hybrid.

Public cloud: This is what people normally end up talking about whenever the

term cloud computing comes up. This is essentially an external cloud, provided

by a service provider. It refers to the resources (hardware, software,

applications) that a service provider offers you over the Internet. Email, if

hosted with an ISP is the most basic and oldest type of service offered on the

public cloud. Now, just about every kind of service you can think of is

available in the public cloud (whole list of these services is provided

elsewhere in this story). The public cloud follows the 'pay as you go' model.

You only pay for the services you consume. The benefits of moving to a public

cloud are many, with the key one being that you don't have to worry about

managing the underlying IT infrastructure-no security patches or updates to

apply, no software upgrades, etc. All these are the service provider's headache.

The three components of a cloud computing network.

Private cloud: A private cloud refers to having your own, private cloud

computing infrastructure. So instead of relying on an external, public cloud

service provider's infrastructure, you would have your own. A private cloud is

more suited for a large enterprise because it has already invested heavily in

its IT infrastructure, data center, apps, etc. A private cloud typically

involves optimizing the existing IT infrastructure, so that it can deliver

services to the users faster and more effectively. A private cloud would allow

the IT team to provision for new hardware, software, and services for users as

and when required. It would provide better control over the entire process of

information processing. This helps reduce costs, improves response time, and

provides greater flexibility.

Hybrid cloud: As the name implies, it is a cloud computing environment that

consists of internal/ external providers, viz. a mix of private and public

clouds. Secure and critical applications are hosted by organizations in the

private cloud while not so critical ones are hosted in the public cloud. This

combination is known as a hybrid cloud. The cloud infrastructure remains as a

unique entity which is bound by a standard technology thus enabling data and

application portability. A very good example of this is cloud bursting, wherein

the organization for its normal usage uses its own infrastructure but moves to

the cloud for peak loads.

Types of cloud services



Whether it's public, private, or hybrid, you could run a range of services

in a cloud computing environment. These can be divided into three parts-SaaS,

IaaS, and PaaS.

SaaS: This is the most familiar and prolific cloud service of all. As

the name suggests, it provides any software application as a service through the

cloud. We've all been using software as a service for years in the public

domain, with the free email services being the most classic example. Today,

there's a whole range of software applications available through SaaS, be it ERP,

CRM, workflow systems, document management, and much more. The cloud service

provider offers these services, and the users pay as they use the same. This

could be on a subscription model, wherein they pay an annual or a monthly fee

for the services. Everything is accessible from a web browser, so the users

don't need anything more than that.

Infrastructure as a Service: As the name implies, IaaS is a service

delivery model in which an organization is given control over different

resources and applications. These resources comprise of storage, hardware,

servers, networking components, etc. The consumer need not manage or control the

underlying cloud infrastructure in this service model. On demand principle is

used in this case as the infrastructure is provided to the user as per his

requirements. It often takes the form of virtualized computing environment thus

giving freedom to consumers wherein they can configure & deploy the applications

in a virtual image locally. Then without the need to worry about the network

infrastructure they can also execute it within the remote environment. Some of

the prime examples of it are Amazon's Elastic Compute Cloud and Simple

Storage Service.

Platform as a Service: This component of cloud computing can be

defined as a set of software and product development tools that allows

developers to create applications on the provider's platform. In other words it

allows you to build applications that are delivered to users through the

Internet and are run on the provider's infrastructure. Cost effectiveness is one

of the prime benefits of PaaS as organizations don't need to spend extra bucks

for buying and managing the underlying hardware and software. PaaS offerings

include facilities for application development and design, testing, deployment

and hosting. Web service integration, database integration, security, storage,

etc that comes under application services is also included. The prime examples

are Salesforce.com's Force.com and Microsoft's Azure.