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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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