UNIT - I CLOUD COMPUTING

Cloud Computing provides us a means by which we can access the applications as utilities, over the

Internet. It allows us to create, configure, and customize applications online.

History

The concept of Cloud Computing came into existence in 1950 with implementation of

mainframe computers, accessible via thin/static clients.

Cloud computing has been evolved from static clients to dynamic ones from software to

services.

The following diagram explains the evolution of cloud computing:

Introduction to Cloud Computing

Cloud computing consists of three different types of computing services delivered remotely

to clients via the internet.

Clients typically give a monthly or annual service fee to providers, to gain access to systems

that deliver software as a service, platforms as a service and infrastructure as a service to

subscribers.

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Clients who subscribe to cloud computing services can reap a variety of benefits, depending

on their particular business needs at a given point in time.

The days of large capital investments in software and IT infrastructure are now a thing of the

past for any enterprise that chooses to adopt the cloud computing model for procurement of

IT services.

The ability to access powerful IT resources on an incremental basis is leveling the playing

field for small and medium sized organizations, providing them with the necessary tools and

technology to compete in the global marketplace, without the previously requisite investment

in on premise IT resources.

What is Cloud?

The term Cloud refers to a Network or Internet. In other words, we can say that Cloud is

something, which is present at remote location.

Cloud can provide services over network, i.e., on public networks or on private networks,

i.e., WAN, LAN or VPN. Applications such as e-mail, web conferencing, customer

relationship management (CRM), all run in cloud.

What is Cloud Computing?

Cloud Computing refers to manipulating, configuring, and accessing the applications

online.

It offers online data storage, infrastructure and application.

We need not to install a piece of software on our local PC and this is how the cloud

computing overcomes platform dependency issues.

Hence, the Cloud Computing is making our business application mobile and collaborative.

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Define:

Cloud computing is the use of various services, such as software development platforms, servers,

storage and software, over the internet, often referred to as the "cloud."

In general, there are three cloud computing characteristics that are common among all cloud-

computing vendors:

1. The back-end of the application (especially hardware) is completely managed by a cloud

vendor.

2. A user only pays for services used (memory, processing time and bandwidth, etc.).

3. Services are scalable

Types of Cloud Computing

This cloud model is composed of five essential characteristics, three service models, and four

deployment models

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Private cloud.

The cloud infrastructure is provisioned for exclusive use by a single organization

comprising multiple consumers (e.g., business units).

It may be owned, managed, and operated by the organization, a third party, or some

combination of them, and it may exist on or off premises.

Public cloud.

The cloud infrastructure is provisioned for open use by the general public.

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It may be owned, managed, and operated by a business, academic, or government

organization, or some combination of them. It exists on the premises of the cloud provider.

Hybrid cloud.

The cloud infrastructure is a composition of two or more distinct cloud infrastructures

(private, community, or public) that remain unique entities, but are bound together by standardized

or proprietary technology that enables data and application portability (e.g., cloud bursting for load

balancing between clouds).

Community cloud.

The cloud infrastructure is provisioned for exclusive use by a specific community of

consumers from organizations that have shared concerns (e.g., mission, security

requirements, policy, and compliance considerations).

It may be owned, managed, and operated by one or more of the organizations in the

community, a third party, or some combination of them, and it may exist on or off

premises.

Basic Concepts

o There are certain services and models working behind the scene making the cloud computing

feasible and accessible to end users.

o Following are the working models for cloud computing:

Deployment Models

Service Models

DEPLOYMENT MODELS

Deployment models define the type of access to the cloud; Cloud can have any of the four

types of access: Public, Private, Hybrid and Community.

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PUBLIC CLOUD The Public Cloud allows systems and services to be easily accessible to the

general public. Public cloud may be less secure because of its openness, e.g., e-mail.

PRIVATE CLOUD The Private Cloud allows systems and services to be accessible within an

organization. It offers increased security because of its private nature.

COMMUNITY CLOUD The Community Cloud allows systems and services to be accessible

by group of organizations.

HYBRID CLOUDThe Hybrid Cloud is mixture of public and private cloud. However, the

critical activities are performed using private cloud while the non-critical activities are performed

using public cloud.

SERVICE MODELS

Service Models are the reference models on which the Cloud Computing is based. These can

be categorized into three basic service models as listed below:

1. Infrastructure as a Service (IaaS)

2. Platform as a Service (PaaS)

3. Software as a Service (SaaS)

There are many other service models all of which can take the form like XaaS, i.e.,

Anything as a Service.

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This can be Network as a Service, Business as a Service, Identity as a Service, Database

as a Service or Strategy as a Service.

The Infrastructure as a Service (IaaS) is the most basic level of service.

Each of the service models make use of the underlying service model, i.e., each inherits the

security and management mechanism from the underlying model, as shown in the following

diagram:

Infrastructure As A Service (Iaas)

IaaS provides access to fundamental resources such as physical machines, virtual machines,

virtual storage, etc.

Both PaaS and SaaS clouds are grounded in IaaS clouds since the company that is providing

the software as a service is also maintaining the infrastructure to run the software in the first

place.  

Choosing an IaaS cloud, your company will have to deal with the complexity, but with it

comes flexibility.

Platform As A Service (Paas)

PaaS provides the runtime environment for applications, development & deployment tools,

etc.

The main benefit of this service is that for very little money you can start your application

with no stress and more than basic development.

Its design allows for a lot of scalability since it is based on cloud computing.

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The only negative of a PaaS cloud is that these services may come with some restrictions that

will not work with your products under any circumstances.

Software As A Service (Saas)

SaaS model allows using software applications as a service to end users.

This service offered by cloud computing is relatively mature and its phrases use those

included in cloud computing.

Cloud applications permit the cloud to be leveraged for software infrastructure.

This reduces the load of support, maintenance and operations because the application is run

on computers that are owned by the vendor.

Advantages

Worldwide Access:

Cloud computing increases mobility, as you can access your documents from any device in

any part of the world.

For businesses, this means that employees can work from home or on business trips, without

having to carry around documents.

This increases productivity and allows faster exchange of information. Employees can also

work on the same document without having to be in the same place.

More Storage:

In the past, memory was limited by the particular device in question. If you ran out of

memory, you would need a USB drive to backup your current device.

Cloud computing provides increased storage, so you won’t have to worry about running out

of space on your hard drive.

Easy Set-Up:

Adjusting your individual settings, such as choosing a password or selecting which devices

you want to connect to the network, is similarly simple.

After that, you can immediately start using the resources, software, or information in

question.

Automatic Updates.

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The cloud computing provider is responsible for making sure that updates are available – you

just have to download them.

This saves you time, and furthermore, you don’t need to be an expert to update your device;

the cloud computing provider will automatically notify you and provide you with

instructions.

Reduced Cost:

Cloud computing is often inexpensive.

The software is already installed online, so you won’t need to install it yourself.

There are many cloud computing applications available for free, such as Dropbox, and

increasing storage size and memory is affordable.

If you need to pay for a cloud computing service, it is paid for incrementally on a

monthly or yearly basis.

By choosing a plan that has no contract, you can terminate your use of the services at any

time; therefore, you only pay for the services when you need them.

Disadvantages

Security:

When using a cloud computing service, you are essentially handing over your data to a third

party.

The fact that the entity, as well as users from all over the world, are accessing the same

server can cause a security issue.

Companies handling confidential information might be particularly concerned about using

cloud computing, as data could possibly be harmed by viruses and other malware.

Privacy:

Cloud computing comes with the risk that unauthorized users might access your information.

To protect against this happening, cloud computing services offer password protection and

operate on secure servers with data encryption technology.

Loss of Control:

Cloud computing entities control the users.

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This includes not only how much you have to pay to use the service, but also what

information you can store, where you can access it from, and many other factors. You depend

on the provider for updates and backups.

If for some reason, their server ceases to operate, you run the risk of losing all your

information.

Internet Reliance:

While Internet access is increasingly widespread, it is not available everywhere just yet.

If the area that you are in doesn’t have Internet access, you won’t be able to open any of the

documents you have stored in the cloud.

Characteristics

There are four key characteristics of cloud computing. They are shown in the following diagram:

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ON DEMAND SELF-SERVICE

Cloud Computing allows the users to use web services and resources on demand. One can

logon to a website at any time and use them.

A consumer can unilaterally provision computing capabilities, such as server time and

network storage, as needed automatically without requiring human interaction with each

service provider.

BROAD NETWORK ACCESS

Since Cloud Computing is completely web based, it can be accessed from anywhere and at

any time.

Capabilities are available over the network and accessed through standard mechanisms that

promote use by heterogeneous thin or thick client platforms (e.g., mobile phones, tablets,

laptops, and workstations).

RESOURCE POOLING

Cloud Computing allows multiple tenants to share a pool of resources. One can share single

physical instance of hardware, database and basic infrastructure.

The provider’s computing resources are pooled to serve multiple consumers using a multi-

tenant model, with different physical and virtual resources dynamically assigned and

reassigned according to consumer demand.

There is a sense of location independence in that the customer generally has no control or

knowledge over the exact location of the provided resources but may be able to specify

location at a higher level of abstraction (e.g., country, state, or datacenter).

Examples of resources include storage, processing, memory, and network bandwidth.

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RAPID ELASTICITY

It is very easy to scale up or down the resources at any time.

Resources used by the customers or currently assigned to customers are automatically

monitored and resources.

Capabilities can be elastically provisioned and released, in some cases automatically, to

scale rapidly outward and inward commensurate with demand.

To the consumer, the capabilities available for provisioning often appear to be unlimited

and can be appropriated in any quantity at any time.

MEASURED SERVICE

Service Models & Deployment Models are described in above section.

Cloud systems automatically control and optimize resource use by leveraging a metering

capability at some level of abstraction appropriate to the type of service (e.g., storage,

processing, bandwidth, and active user accounts).

Resource usage can be monitored, controlled, and reported, providing transparency for both

the provider and consumer of the utilized service.

Move to cloud computing

Cloud migration is the process of moving data, applications or other business elements to

a cloud computing environment.

There are various types of cloud migrations an enterprise can perform.

One common model is the transfer of data and applications from a local, on-premises data

center to the public cloud.

Cloud migration could also entail moving data and applications from one cloud platform or

provider to another -- a model known as cloud-to-cloud migration.

A third type of migration is to uncloud -- also known as a reverse cloud

migration or declouding -- where data or applications are moved off of the cloud and back

to a local data center.11

Benefits of cloud migration

The general goal or benefit of any cloud migration is to host applications and data in the most

effective IT environment possible, based on factors such as cost, performance and security.

For example: Many organizations perform the migration of on-premises applications and

data from their local data center to public cloud infrastructure.

Cloud migration process

The steps or processes an enterprise follows during a cloud migration vary based on factors

such as the type of migration it wants to perform and the specific resources it wants to move.

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Common elements of a cloud migration strategy include evaluating performance and

security requirements, choosing a cloud provider, calculating costs and making any

necessary organizational changes.

Common challenges an enterprise faces during a cloud migration include interoperability,

data and application portability, data integrity and security.

Without proper planning, a migration could negatively affect workload performance and lead

to higher IT.

An enterprise may choose to move an application to its new hosting environment without any

modifications -- a model sometimes referred to as a lift-and-shift migration.

In other cases, it might be more beneficial to make changes to an application's code or

architecture before performing the migration.

In terms of data transfers from its local data center to the public cloud, an enterprise also

has several options.

These include the use of the public internet, a private/dedicated network connection or

an offline transfer, in which an organization uploads its local data onto an appliance and

then physically ships that appliance to a public cloud provider, which then uploads the data to

the cloud.

The type of data migration an enterprise chooses -- online or offline -- depends on the

amount and type of data it wants to move, as well as how fast it needs to complete the

migration.

Cloud migration tools and services

There are various tools and services available to help an enterprise plan and execute a cloud

migration.

For example, public cloud providers, including Amazon Web Services (AWS),Microsoft

Azure and Google, offer cloud migration services to support private/dedicated networks

for data transfers, as well offline migrations.

Public cloud providers also offer tools to help an enterprise plan and track the progress of a

migration.

Examples of migration services from public cloud providers include:

AWS Migration Hub

Azure Migrate

Google Cloud Data Transfer Service13

AWS Snowball

Azure Import/Export

Google Transfer Appliance

There are also third-party vendors that offer cloud migration services and tools, such as CloudVelox,

Racemi and RiverMeadow.

Working of cloud computing

Cloud computing refers to storing and sharing of resources, software, and information over

the internet.

The information is stored on physical servers maintained and controlled by a cloud

computing provider, such as Apple in regards to iCloud.

As a user, you access your stored information on the cloud via the Internet.

By using cloud storage, you don’t have to store the information on your own hard drive.

Instead, you can access it from any location and download it onto any device of your choice,

including laptops, tablets, or smartphones.

You can also edit files, such as Word documents or PowerPoint presentations,

simultaneously with other users, making it easier to work away from the office.

It is divided into two parts, which are:

Front end and

Back end

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FRONT END

Front End refers to the client part of cloud computing system. It consists of interfaces and

applications that are required to access the cloud computing platforms, e.g., Web Browser.

BACK END

Back End refers to the cloud itself. It consists of all the resources required to provide cloud

computing services. It comprises of huge data storage, virtual machines, security mechanism,

services, deployment models, servers, etc.

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