Cloud computing allows users to access computing resources like servers, storage, databases, networking, software, analytics and intelligence over the internet. It utilizes centralized data centers that can be accessed via the internet from various devices. There are different cloud service models like Infrastructure as a Service, Platform as a Service and Software as a Service. The architecture consists of a front end interacting with clients and a back end comprising servers, storage and other computing resources in the cloud. Virtualization allows multiple virtual machines to run on a single physical machine in the cloud. Major cloud platforms include Windows Azure, Google App Engine and Amazon Web Services.

1. CLOUD COMPUTING
BY
GIRISH MENON

3. INTRODUCTION
Cloud computing, is a colloquial expression used to describe a variety
of different types of computing concepts that involve a large number of
computers connected through a real-time communication network such
as the Internet. In marketing, cloud computing is mostly used to sell
hosted services in the sense of application service provisioning that run
client server software at a remote location. Such services are given
popular acronyms like Software as a Service, Platform as a Service,
Infrastructure as a Service, Hardware as a Service and Everything as a
Service.

4. HOW IT WORKS
 Utilizes the network as a means to connect user end point to
resources that are centralized in a data center.
 The data center may by accessed via the internet or a
company network, or both.
 Allows access from a variety of end points such as a mobile
phone, a PC or a tablet.
 Cloud services may be designed to be vendor agnostic,
working equally well with Linux, Mac and PC platforms.

5. HOW IT WORKS
 Allows access from any internet connected location, allowing
Telecommuting, and Outsourcing.
 A user endpoint with minimal software requirements may
submit a task for processing. The service provider may pool the
processing power of multiple remote computers in "the cloud"
to achieve the task, such as data warehousing of hundreds of
terabytes, managing and synchronizing multiple documents
online, or computationally intensive work.

6. ARCHITECTURE

7. ARCHITECTURE
 The two most significant components of cloud computing
architecture are known as the front end and the back end.
 The front end is the part seen by the client, i.e. the computer user.
This includes the client’s network and applications used to access
the cloud via a user interface such as a web browser.
 The back end of the cloud computing architecture is the ‘cloud’ itself,
comprising various computers, servers and data storage devices.

8. CLOUD SERVICE MODELS

9. LAYERS
 Client
 Application
 Platform
 Infrastructure
 Server

10. VIRTUALIZATION
• Virtual workspaces:
– An abstraction of an execution environment that can be made dynamically available
to authorized clients by using well-defined protocols,
– Resource quota (e.g. CPU, memory share),
– Software configuration (e.g. O/S, provided services).
• Implement on Virtual Machines (VMs):
– Abstraction of a physical host machine,
– Hypervisor intercepts and emulates instructions from VMs, and allows management
of VMs,
– VMWare, Xen, etc.
• Provide infrastructure API:
– Plug-ins to hardware/support structures

11. VIRTUAL MACHINES
• VM technology allows multiple virtual
machines to run on a single physical
machine.
Hardware
Virtual Machine Monitor (VMM) / Hypervisor
Guest OS
(NetBSD)
Guest OS
(Windows)
VM VM VM
App AppApp
Xen
VMWare
UML
Denali
etc.
Guest OS
(Linux)
AppApp App

12. CLOUD SERVICES
• WINDOWS AZURE
• GOOGLE APP ENGINE
• AMAZON SERVICES

13. WINDOWS AZURE
• Enterprise-level on-demand capacity builder
• Fabric of cycles and storage available on-request for a cost
• You have to use Azure API to work with the infrastructure offered
by Microsoft
• Significant features: web role, worker role , blob storage, table
and drive-storage

14. GOOGLE APP ENGINE
• This is more a web interface for a development environment that offers a
one stop facility for design, development and deployment Java and
Python-based applications in Java, Go and Python.
• Google offers the same reliability, availability and scalability at par with
Google’s own applications
• Interface is software programming based
• Comprehensive programming platform irrespective of the size (small or
large)
• Signature features: templates and appspot, excellent monitoring and
management console

15. AMAZON SERVICES
• Amazon EC2 is one large complex web service.
• EC2 provided an API for instantiating computing instances with any of
the operating systems supported.
• It can facilitate computations through Amazon Machine Images (AMIs)
for various other models.
• Signature features: S3, Cloud Management Console, MapReduce
Cloud, Amazon Machine Image (AMI)
• Excellent distribution, load balancing, cloud monitoring tools

16. ADVANTAGES
• Lower computer costs
• Improved performance
• Reduced software costs
• Instant software updates
• Improved document format compatibility

17. CONS
• Requires a constant Internet connection
• Does not work well with low-speed connections
• Features might be limited
• Response Can be slow

18. CHALLENGES
• Issues relating to policy and access
• Security could prove to be a big issue
• Use of cloud computing means dependence on others and that could
possibly limit flexibility and innovation.