Cloud Computing
Dave Elliman
1
G53ELC
28/06/2016
The datacenter is the computer!
Source: NY Times (6/14/2006)
Two Key Enterprise Technologies
for the Cloud

Message Oriented Middleware (MOM)
Allows load sharing and loose coupling and is robust to server
failure.

Virtualization:
The ability to run multiple operating systems on a single physical
system and share the underlying hardware resources
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A definition

Cloud Computing:
“The provisioning of services in a timely (near instant), on-demand
manner, to allow the scaling up and down of resources”
Requirements…

IApplications are International and expect users from
anywhere in the world

Applications access huge (Petabyte) databases

Applications expect to download content rapidly anywhere

Applications need to scale with user load without degrading
response

Applications need to be available 24/7 365 days a year

Applications need to be secure and well defended

Companies wish to pay only for bandwidth and server time
used
What’s a Petabyte?

1024 Bytes
= 1 Kilobyte

1024 Kilobytes = 1 Megabyte

1024 Megabyte = 1 GigaByte

1024 Gibabytes = 1 Terabyte

1024 Terabyte = 1 Petabyte

Exercise for the student: Write down the number of
bytes in a Petabyte as a number
Petrabyte applications are not
unusual nowadays

Google believed to processes 30 PB a day

eBay has 7 PB of user data

Facebook has 36 PB of user data
A million times cheaper since 1980
The communications growth rate is
also amazing
Why not just set up your own servers?

Lot’s of reasons…

Will give an example…
Suppose you are Forbes.com

You offer on-line real
time stock market
data

Why pay for capacity
weekends, overnight?
9 AM - 5 PM,
M-F
Rate of
Server
Accesses
ALL OTHER
TIMES
Forbes' Solution

Host the web site in Amazon's EC2 Elastic Compute
Cloud

Provision new servers every day, and deprovision
them every night

Pay just $0.10* per server per hour


* more for higher capacity servers
Let Amazon worry about the hardware, the scaling, the
local (edge) delivery, the security, the availability, and
the backup(?).
Cloud computing takes virtualization
to the next step
 You
don’t have to own the hardware
 You
“rent” it as needed from a cloud
 There

A

are public clouds
e.g. Amazon EC2, and now many others
(Microsoft Azure, IBM, Sun, and others ...)
company can create a private cloud
With more control over security, etc.
Lower Cost
 No
need to pay for infrastructure up
front
 No
need for expensive support staff
 only
pay for what you use
 Great
for start-ups – may even be free
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More Agile
 It
used to take 3 months to set up an
application on a cluster of servers
 Takes
half an hour in the cloud
 Scale
up or down (elasticity)
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OK It’s a good idea. How does it
work?

We already saw how to set up a RESTful web service on
the Amazon cloud. It took five minutes.

Very easy to serve static web pages in this way

Quite simple to store and access data in the cloud as files
or databases

More tricky to set up large scalable applications, but this is
where really big pay-offs are possible.
How Cloud Computing Works

Various providers let you create virtual servers


You create virtual servers ("virtualization")





Set up an account, perhaps just with a credit card
Choose the OS and software each "instance" will have
It will run on a large server farm located somewhere
You can instantiate more on a few minutes' notice
You can shut down instances in a minute or so
They send you a bill for the processor time and
comms bandwidth that you use
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Virtualisation is the key technology

We will look at how this is done in another lecture
Worries?

How do I pick a provider?

Is my data secure?

Do I have any control over where my data is moved
to?

How can I be sure the provider will live up to all those
promises?
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(footnote)
How come Amazon?

It arose out of efforts to manage Amazon’s own services



(Each time you get a page from Amazon, over a hundred servers
are involved)
See reference Amazon Architecture on ELC web page
They got so good at it that they launched Amazon Web
Services (AWS) as a product
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Cloud Computing Status

Seems to be rapidly becoming a mainstream practice

Numerous providers


Amazon EC2 imitators ...
Just about every major industry name
• IBM, Sun, Microsoft, ...

Major buzz at industry meetings
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The revolution

Rent it instead of build it – pay for what you use

Rely on the experts to solve all those worries..

There is a major revolution underway in how we
manage hardware


Use many servers with virtualization
Applications organized with MOM

Data cached close to delivery point

Deployment and monitoring are in-house
functions
Any comments/Questions