Modified from Mark Baker

What is Cloud Computing?

• Cloud Computing is a general term used to describe a
new class of network based computing that takes place
over the Internet,
– basically a step on from Utility Computing
– a collection/group of integrated and networked
hardware, software and Internet infrastructure (called
a platform).
– Using the Internet for communication and transport
provides hardware, software and networking services
to clients
• These platforms hide the complexity and details of the
underlying infrastructure from users and applications by
providing very simple graphical interface or API
(Applications Programming Interface). 2
What is Cloud Computing?
• In addition, the platform provides on demand services,
that are always on, anywhere, anytime and any place.
• Pay for use and as needed, elastic
– scale up and down in capacity and functionalities
• The hardware and software services are available to
– general public, enterprises, corporations and
businesses markets

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Cloud Summary
• Cloud computing is an umbrella term used to refer to
Internet based development and services
• A number of characteristics define cloud data,
applications services and infrastructure:
– Remotely hosted: Services or data are hosted on
remote infrastructure.
– Ubiquitous: Services or data are available from
anywhere.
– Commodified: The result is a utility computing model
similar to traditional that of traditional utilities, like gas
and electricity - you pay for what you would want!

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Cloud Architecture

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What is Cloud Computing

• Shared pool of configurable computing resources

• On-demand network access
• Provisioned by the Service Provider
Cloud Computing Characteristics
Common Characteristics:
Massive Scale Resilient Computing
Homogeneity Geographic Distribution

Virtualization Service Orientation

Low Cost Software Advanced Security

Essential Characteristics:

On Demand Self-Service
Broad Network Access Rapid Elasticity
Resource Pooling Measured Service

Adopted from: Effectively and Securely Using the Cloud Computing Paradigm by peter Mell, Tim 7
Grance
 Cloud Computing Service Layers
Services Description
Services – Complete business services such as
Services PayPal, OpenID, OAuth, Google Maps, Alexa

Application Application – Cloud based software that eliminates

Application the need for local installation such as Google Apps,
Focused Microsoft Online

Development – Software development platforms used

Development to build custom cloud based applications (PAAS &
SAAS) such as SalesForce

Platform – Cloud based platforms, typically provided

Platform using virtualization, such as Amazon ECC, Sun Grid

Storage – Data storage or cloud based NAS such

Infrastructure Storage as CTERA, iDisk, CloudNAS

Focused
Hosting – Physical data centers such as those run
Hosting by IBM, HP, NaviSite, etc.

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Basic Cloud Characteristics
• The “no-need-to-know” in terms of the underlying
details of infrastructure, applications interface with the
infrastructure via the APIs.
• The “flexibility and elasticity” allows these systems to
scale up and down at will
– utilising the resources of all kinds
• CPU, storage, server capacity, load balancing, and
databases
• The “pay as much as used and needed” type of utility
computing and the “always on!, anywhere and any
place” type of network-based computing.

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Basic Cloud Characteristics
• Cloud are transparent to users and applications, they
can be built in multiple ways
– branded products, proprietary open source, hardware
or software, or just off-the-shelf PCs.
• In general, they are built on clusters of PC servers and
off-the-shelf components plus Open Source software
combined with in-house applications and/or system
software.

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 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
What is the purpose and benefits?
• Cloud computing enables companies and applications,
which are system infrastructure dependent, to be
infrastructure-less.
• By using the Cloud infrastructure on “pay as used and on
demand”, all of us can save in capital and operational
investment!
• Clients can:
– Put their data on the platform instead of on their own
desktop PCs and/or on their own servers.
– They can put their applications on the cloud and use
the servers within the cloud to do processing and data
manipulations etc.

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Cloud-Sourcing

• Why is it becoming a Big Deal:

– Using high-scale/low-cost providers,
– Any time/place access via web browser,
– Rapid scalability; incremental cost and load sharing,
– Can forget need to focus on local IT.
• Concerns:
– Performance, reliability, and SLAs,
– Control of data, and service parameters,
– Application features and choices,
– Interaction between Cloud providers,
– No standard API – mix of SOAP and REST!
– Privacy, security, compliance, trust…
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Some Commercial Cloud Offerings

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Cloud Taxonomy

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Cloud Storage
• Several large Web companies are now exploiting the fact
that they have data storage capacity that can be hired
out to others.
– allows data stored remotely to be temporarily cached
on desktop computers, mobile phones or other
Internet-linked devices.

• Amazon’s Elastic Compute Cloud (EC2) and Simple

Storage Solution (S3) are well known examples
– Mechanical Turk

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Amazon Simple Storage Service (S3)
• Unlimited Storage.
• Pay for what you use:
– $0.20 per GByte of data transferred,
– $0.15 per GByte-Month for storage used,
– Second Life Update:
• 1TBytes, 40,000 downloads in 24 hours - $200,

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Utility Computing – EC2
• Amazon Elastic Compute Cloud (EC2):
– Elastic, marshal 1 to 100+ PCs via WS,
– Machine Specs…,
– Fairly cheap!
• Powered by Xen – a Virtual Machine:
– Different from Vmware and VPC as uses “para-
virtualization” where the guest OS is modified to use
special hyper-calls:
– Hardware contributions by Intel (VT-x/Vanderpool)
and AMD (AMD-V).
– Supports “Live Migration” of a virtual machine
between hosts.
• Linux, Windows, OpenSolaris
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• Management Console/AP
Opportunities and Challenges
• The use of the cloud provides a number of opportunities:
– It enables services to be used without any
understanding of their infrastructure.
– Cloud computing works using economies of scale:
• It potentially lowers the outlay expense for start up
companies, as they would no longer need to buy
their own software or servers.
• Cost would be by on-demand pricing.
• Vendors and Service providers claim costs by
establishing an ongoing revenue stream.
– Data and services are stored remotely but accessible
from “anywhere”.
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 Opportunities and Challenges
• In parallel there has been backlash against cloud
computing:
– Use of cloud computing means dependence on
others and that could possibly limit flexibility and
innovation:
• The others are likely become the bigger Internet
companies like Google and IBM, who may
monopolise the market.
• Some argue that this use of supercomputers is a
return to the time of mainframe computing that the
PC was a reaction against.
– There are also issues relating to policy and access:
• There have been cases of users being locked out
of accounts and losing access to data. 21
Advantages of Cloud
• Lower computer costs:
– You do not need a high-powered and high-priced
computer to run cloud computing's web-based
applications.
– Since applications run in the cloud, not on the desktop
PC, your desktop PC does not need the processing
power or hard disk space demanded by traditional
desktop software.
– When you are using web-based applications, your PC
can be less expensive, with a smaller hard disk, less
memory, more efficient processor...
– In fact, your PC in this scenario does not even need a
CD or DVD drive, as no software programs have to be
loaded and no document files need to be saved. 22
Advantages of Cloud
• Improved performance:
– With few large programs hogging your computer's
memory, you will see better performance from your PC.
– Computers in a cloud computing system boot and run
faster because they have fewer programs and
processes loaded into memory…
• Reduced software costs:
– Instead of purchasing expensive software applications,
you can get most of what you need for free-ish!
• most cloud computing applications today, such as the
Google Docs suite.
– better than paying for similar commercial software
• which alone may be justification for switching to cloud
applications. 23
 Advantages of Cloud
• Instant software updates:
– Another advantage to cloud computing is that you are no
longer faced with choosing between obsolete software
and high upgrade costs.
– When the application is web-based, updates happen
automatically
– When you access a web-based application, you get the
latest version
• Improved document format compatibility.
– You do not have to worry about the documents you create
on your machine being compatible with other users'
applications or OSes
– There are potentially no format incompatibilities when
everyone is sharing documents and applications in the24
cloud.
Advantages of Cloud
• Unlimited storage capacity:
– Cloud computing offers virtually limitless storage.
– Your computer's current 1 Tbyte hard drive is small
compared to the hundreds of Pbytes available in the
cloud.
• Increased data reliability:
– Unlike desktop computing, in which if a hard disk
crashes and destroy all your valuable data, a
computer crashing in the cloud should not affect the
storage of your data.
• if your personal computer crashes, all your data is
still out there in the cloud, still accessible

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Advantages of Cloud
• Universal document access:
– That is not a problem with cloud computing, because
you do not take your documents with you.
– Instead, they stay in the cloud, and you can access
them whenever you have a computer and an Internet
connection
– Documents are instantly available
• Latest version availability:
– When you edit a document at home, that edited version
is what you see when you access the document at
work.
– The cloud always hosts the latest version of your
documents
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Advantages of Cloud
• Easier group collaboration:
– Sharing documents leads directly to better collaboration.
– Many users do this as it is an important advantages of
cloud computing
• multiple users can collaborate easily on documents
and projects
• Device independence.
– You are no longer tethered to a single computer or
network.
– Changes to computers, applications and documents
follow you through the cloud.
– Move to a portable device, and your applications and
documents are still available.
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Disadvantages of Cloud
• Requires a constant Internet connection:
– Cloud computing is impossible if you cannot connect
to the Internet.
– Since you use the Internet to connect to both your
applications and documents, if you do not have an
Internet connection you cannot access anything, even
your own documents.
– A dead Internet connection means no work and in
areas where Internet connections are few or
inherently unreliable, this could be a deal-breaker.

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Disadvantages of Cloud
• Does not work well with low-speed connections:
– Similarly, a low-speed Internet connection, such as that
found with dial-up services, makes cloud computing
painful at best and often impossible.
– Web-based applications require a lot of bandwidth to
download, as do large documents.
• Features might be limited:
– This situation is bound to change, but today many web-
based applications simply are not as full-featured as
their desktop-based applications.
• For example, you can do a lot more with Microsoft
PowerPoint than with Google Presentation's web-
based offering
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Disadvantages of Cloud
• Can be slow:
– Even with a fast connection, web-based applications
can sometimes be slower than accessing a similar
software program on your desktop PC.
– Everything about the program, from the interface to
the current document, has to be sent back and forth
from your computer to the computers in the cloud.
– If the cloud servers happen to be backed up at that
moment, or if the Internet is having a slow day, you
would not get the instantaneous access you might
expect from desktop applications.

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Disadvantages of Cloud Computing
• Stored data might not be secure:
– With cloud computing, all your data is stored on the
cloud.
• The questions is How secure is the cloud?
– Can unauthorised users gain access to your confidential
data?
• Stored data can be lost:
– Theoretically, data stored in the cloud is safe, replicated
across multiple machines.
– But on the off chance that your data goes missing, you
have no physical or local backup.
• Put simply, relying on the cloud puts you at risk if the
cloud lets you down.
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 Disadvantages of Cloud
• General Concerns:
– Each cloud systems uses different protocols and
different APIs
• may not be possible to run applications between
cloud based systems
– Amazon has created its own DB system (not SQL 92),
and workflow system (many popular workflow systems
out there)
• so your normal applications will have to be adapted
to execute on these platforms.

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The Future of Cloud
• Many of the activities loosely grouped together under
cloud computing have already been happening and
centralised computing activity is not a new phenomena
• Grid Computing was the last research-led centralised
approach
• However there are concerns that the mainstream
adoption of cloud computing could cause many problems
for users
• Many new open source systems appearing that you can
install and run on your local cluster
– should be able to run a variety of applications on
these systems

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