What is cloud computing
• Cloud computing is a subscription-based service which enables you can
obtain computer resources through internet(cloud).
• These resources are hosted/owned by what we call ‘cloud providers’.
• Users are provided an interface to interact with the resources.
• These resources can be rapidly implemented and decommissioned, and
scaled up or down providing for an on-demand utility-like model.
• AMAZON played a key role in all the development of cloud
computing by modernizing their data centers
• Amazon initiated a new product development effort to
provide cloud computing to external customers, and
launched amazon web services (AWS) on a utility computing
basis in 2006
Why cloud computing
• You no longer have to pay for someone (or a team of someones) to do things such
as install and update software, install and manage email servers
• You no longer have to buy software.
• Cloud computing applications are regularly updated, so you don't have to spend
time and money doing it
• Access your data from anywhere
• Cloud computing lets you start up or grow your small business quickly.
• On-demand service
– Get computing capabilities as needed automatically
• Broad Network Access
– Services available over the net using desktop, laptop, PDA, mobile phone
• Resource pooling
– Provider resources pooled to serve multiple clients
• Rapid Elasticity
– Ability to quickly scale in/out service
• Measured service
– control, optimize services based on metering
• Its one of the ways in which you will access services on cloud
• Separates OS from hardware and from apps.
• Transfers entire OS from one hardware to another.
• Done through virtualisation software
• Two types
On h/w install OS and then virtualisation software.
This allows you to have mutiple OS.(called instances).- eg: virtualbox
These OS Open up like windows .
Eg: MAC computer you install vmware fusion and on top of it you can install
windows 7 that just looks like an application.
We can simply copy and paste OS to another server.
• More powerful than client installed
• Two pieces of s/w
2. Management software
• A kind of doftware that you directly install on h/w where you want to run
Eg: vmware’s hypervisor is ESXI.
Install ESXI on h/w.
2. Management software
• Management s/w is what connects to hypervisor(vsphere)
• Through this we are able to create virtual servers for different clients
• These virtual servers can be transferred to any other server running esxi
hypervisor by managment s/w.
• Management s/w can do fault tolerance.
• IIT delhi -BAADAL
• As now h/w can be separated from o/s
• Companies now realised that they could sell instances of OS .
• Instead of buying h/w create instance in our virtual environment and use
• Pay for what you use
• Eg: amazon ec2
Cloud Service Models
• Software as a Service (SaaS)
– Application is hosted as a service to customers who access via internet.
– Users don’t have to maintain or support it.
– It’s out of customers hand when hosting service decides to change it.
Eg : googledocs, salesforce (crm),quickbooks.com
Costing less money
Less staff required
SSL widely used and trusted
Organisation that has a very specific computational need may not be able to find
application through saas
• Platform as a Service (PaaS)
– Users design,develop and deploy their apps on the cloud through the
environment provided by cloud provider.
Eg: google app engine, microsoft’s windows azure,
• 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.
• If you create an application with one cloud provider and decide to move to
other cloud provider-you may either not be able to do so or have to pay a
• If provider goes out of business your apps are lost. Eg: company zimki
• Infrastructure as a Service (IaaS)
• Rather than purchasing servers,softwares,racks and having to pay for the
space, the cloud provider rents those resources.
• Iaas provides resources as Server space,network equipment,memory,storage
space and cpu cycles.
• Dynamically scaled up and down.
• Providers charge according to resources used.
Amazon elastic compute cloud( EC2)
• Offers virtual machines for the organisations.
• Amazon simple storage service s3 allows you to store your data.
Google drive: upto 5gb storage allowed for free
No control over data(prone to hackers)
Even best of companies can go down at times.-like amazon s3 in 2008
How do clients access data on cloud
• First a terminal server is created by cloud provider.
• Each user gets a unique virtual session on the server.
• As terminal server and client data reside on same n/w. So connection to
data is fast.
• All the unique softwares installed on terminal servers become available to
all users within virtual session.
• These sessions are protected by firewalls,anti-virus,encryption etc
• A public cloud can be accessed by any subscriber with an internet connection and
access to the cloud space . Eg: amazon ec2,google app engine etc
A private cloud is established for a specific group or organization and limits access to
just that group.it may be managed by the org or a 3rd party, on or off the
A hybrid cloud is essentially a combination of at least two clouds, where the
clouds included are a mixture of public, private, or community.
• Community Cloud - A community cloud is shared among two or more
organizations that have similar cloud requirements.
Disadvantages of cloud computing
• Possible downtime
Cloud computing makes your small business dependent on the reliability of your
Internet connection. And even the most reliable cloud computing service
providers suffer server outages now and again.
You could be locking your business. You can't insert a document created in another
application into a Google Docs spreadsheet.
Data stored on the cloud can be prone to hackers and a dishonest admin can tamper
• Cloud computing can be really useful for those who want to
start business but don’t have enough money to support it.
• Even though the security continues to be the main concern in
cloud computing but it may well be better than than your own
• If your data is on the cloud you need not to worry about
theft, damage,fire etc.