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What is Cloud Computing
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Cloud Computing Service Models
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Deployment Models in Cloud Computing
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Advantages and Disadvantages of Cloud Computing
What is Cloud Computing?
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Cloud is just a metaphor for the internet, when
we say cloud, we are just referring to internet.
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In the simplest terms, cloud computing means
storing and accessing data and programs over the Internet instead of our local
computer's hard drive.
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The phrase cloud computing means "a type of
Internet-based computing" where different services — such as servers,
storage and applications — are delivered to an organization's computers and
devices through the Internet.
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Cloud Computing refer to a variety of services
available over the Internet that deliver computing functionality on the service
provider's infrastructure.
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A cloud computing service consists of highly
optimized data centers (third party data centers from the end user point of
view), that provide various hardware, software and information resources (when
needed).
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Cloud platform hide the complexity and details
of the underlying infrastructure from users and applications by providing very
simple graphical interface or API (Applications Programming Interface).
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The Cloud platform provides on demand services
that are always on, anywhere, anytime and anyplace.
Why are businesses moving to cloud?
In traditional hosting, a software company has to deal with
licensing costs, protection of data, frequent upgrades to latest technologies,
maintenance and up gradation of hardware and most important finding the right
skillsets at the right time.
Cloud Characteristics
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Characteristics of Cloud computing that
distinguish it from traditional hosting.
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Remotely hosted: Services or data are hosted on
remote infrastructure.
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Ubiquitous: Services or data are available from
anywhere through internet.
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Resiliency: Cloud providers generally mirrors
solutions to multiple data centers to minimize downtime in the event of a
disaster.
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On-demand self-service: A consumer can himself
provision computing capabilities, such as server time and network storage, as
needed automatically without requiring human interaction with each service’s provider.
It is sold on demand mostly by the minutes or hours. (Pay as you go model)
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Rapid elasticity – A user can utilize as much or
little of the cloud service as required. For example resources (ex: webservers)
on the cloud can be scaled to meet high traffic in peak times or scaled down in
times of less traffic.
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Broad network access. 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, laptops, and
PDAs).
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Fully managed by the provider - The user is
abstracted from the details of how the service is managed in the cloud. For
example the user need not worry about aspects such as hardware used, software
updates and patches, plug-ins, web security. There is optimum utilization of
resources and as well as sharing of resources. Everything is taken care of by
the provider.
Cloud Computing Service Models
Cloud Computing = Software as a Service (SaaS)
+ Platform as a
Service (PaaS)
+ Infrastructure as
a Service (IaaS)
1) IaaS
(Infrastructure as a Service):
a. Delivers computer
infrastructure, typically a platform virtualization environment as a
service.
b. Cloud providers build
datacenters, managing power, scale, hardware, networking, storage, distributed
systems, etc
c. Rather than purchasing servers,
software, data center space or network equipment, clients instead buy those
resources as a fully outsourced service.
d. Eg: Amazon Web Services(AWS),
Rackspace Hosting, VMWare, Citrix
2) PaaS (Platform as a Service):
a. Provides developer's necessary
tools to create, test, host and maintain created applications.
b. Cloud providers offer an
Internet-based platform to developers who create services but don't want to
build their own cloud.
c. Ex: Windows Azure, Google App.
3) SaaS (Software as a Service):
a. From end user’s point of view
apps are located in the cloud and it is almost always accessible
through a web browser.
b. Any application hosted on a
remote server that can be accessed over the Internet is considered as
SaaS.
c. Ex: Windows Azure, Gmail, Google
Apps (Office like features), Sales Force CRM
The following picture neatly summarizes the functionality of
the three service models of the cloud.
Deployment Models in Cloud Computing
There are three main deployment models in Cloud Computing.
1. Public Cloud:
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These are the clouds which are open for use by
general public and they exist beyond the firewall of an organization, fully
hosted and managed by vendors.
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Your data is stored in the provider’s data
center and the provider is responsible for the management and maintenance of
the data center.
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Because you are sharing computing resources
among a network of users, the public cloud offers greater flexibility and cost
savings.
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This is good option if your demand for computing
resources fluctuates. You have to purchase the capacity on the basis of usage
and can scale up or scale down server capabilities based on traffic and other
dynamic requirements.
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This type of cloud environment is appealing to
many companies because it reduces lead times in testing and deploying new
products.
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Cons: They are more vulnerable than private
clouds and there is no control of resources used or who shares them.
Note: Even though you don’t control the security of a public
cloud, all of your data remains separate from others and security breaches of
public clouds are rare.
2. Private Cloud:
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A private cloud hosting solution, also known as
an internal or enterprise cloud, resides on company’s intranet or hosted data
center where all of your data is protected behind a firewall.
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This can be a great option for companies who
already have expensive data centers because they can use their current infrastructure.
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You go for a private cloud when you have strict
security and data privacy issues.
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Cons: The main drawback people see with a
private cloud is that all management, maintenance and updating of data centers
is the responsibility of the company.
3. Hybrid Clouds:
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They consist of external and internal providers,
namely a mix of public and private clouds.
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Secure & critical apps are managed by an
organization and the not-so-critical & secure apps by the third party
vendor. For example, you can use a public cloud to interact with the clients
but keep their data secured within a private cloud. Most companies are now
switching to Hybrid clouds.
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Ideal in situations where you have plans are to
migrate to a complete cloud solution as existing hardware expires or you have
some applications or hardware that are not ready for the cloud
Advantages and Disadvantages of Cloud Computing
Advantages of Cloud Computing:
1. Lower Computer Cost
2. Improved Performance
3. Reduced Software Cost and Instant
Software Updates
4. Unlimited Storage Capacity
5. Universal Document Access
6. Increased data reliability
7. Device Independence
Disadvantage of Cloud Computing:
1. Requires a constant Internet
connection.
2. Does not work well with
low-speed connections.
3. Features might be limited based
on provider you choose.
4. Can be slow.
5. Stored data might not be secure.
6. If your data is stored abroad whose policy do
you adhere to?
