
Cloud computing
Last updated: February 5, 2010.
History has a funny way of repeating itself, or so they say.
But it may come as some surprise to find this old cliché applies just as much to
the history of computers as to wars, revolutions, and kings and queens. For the
last three decades, one trend in computing has been loud and clear:
big, centralized, mainframe systems have been "out";
personalized, power-to-the-people, do-it-yourself PCs have been "in."
Before personal computers took off in the early 1980s, if your
company needed sales or payroll figures calculating in a hurry, you'd
most likely have bought in specialized "data-processing" services
from another company, with its own expensive computer systems, that
specialized in number crunching; these days, you can do the job
just as easily on your desktop with off-the-shelf software. Or can
you? In a striking throwback to the 1970s, many companies are
finding, once again, that buying in computer services makes more
business sense than do-it-yourself. This new trend is called cloud
computing and, not surprisingly, it's linked to the Internet's
inexorable rise. What is cloud computing? How does it work? Let's
take a closer look!
Photo: Cloud computing: the hardware, software, and applications
you're using may be anywhere up in the "cloud." As long as it all does what you want, you don't need
to worry where it is or how it works. Composite photo by Explainthatstuff.com based on a picture of an IBM Blue Gene/P
supercomputer, by courtesy of Argonne National Laboratory, published under a Creative Commons Licence, and a cloud photo by Brian Ferguson courtesy of US Air Force.
What is cloud computing?
Cloud computing means that instead of all the computer
hardware and software you're using sitting on your desktop, or somewhere inside your company's network, it's
provided for you as a service by another company and accessed
over the Internet, usually in a completely seamless way. Exactly
where the hardware and software is located and how it all works
doesn't matter to you, the user—it's just somewhere up in the
nebulous "cloud" that the Internet represents.
Cloud computing is a buzzword that means different things to different people. For some, it's just
another way of describing IT (information technology) "outsourcing";
others use it to mean any computing service provided over the
Internet or a similar network; and some define it as any bought-in computer
service you use that sits outside your firewall. However we
define cloud computing, there's no doubt it makes most sense when we
stop talking about abstract definitions and look at some simple, real
examples—so let's do just that.
Simple examples of cloud computing
Most of us use cloud computing all day long without realizing it. When you sit at
your PC and type a query into Google, the computer on your desk isn't
playing much part in finding the answers you need: it's no more than
a messenger. The words you type are swiftly shuttled over the Net to
one of Google's hundreds of thousands of clustered PCs, which dig out your results and send them promptly back to you. When you do a Google
search, the real work in finding your answers might be done by a
computer sitting in California, Dublin, Tokyo, or Beijing;
you don't know—and most likely you don't care!
The same applies to Web-based email. Once upon a time, email was something you
could only send and receive using a program running on your PC (sometimes called a mail client). But then
Web-based services such as Hotmail came along and carried email off
into the cloud. Now we're all used to the idea that emails can be
stored and processed through a server in some remote part of the world, easily
accessible from a Web browser, wherever we happen to be. Pushing email off into
the cloud makes it supremely convenient for busy people, constantly on the move.
Preparing documents over the Net is a newer example of cloud computing. Simply log on to
a web-based service such as Google Documents and you can
create a document, spreadsheet, presentation, or whatever you like using
Web-based software. Instead of typing your words into a program like Microsoft Word or
OpenOffice, running on your computer, you're using similar software running on
a PC at one of Google's world-wide data centers. Like an email drafted on Hotmail,
the document you produce is stored remotely, on a Web server, so you can access it from any
Internet-connected computer, anywhere in the world, any time you like. Using a Web-based
service like this means you're "contracting out" or "outsourcing"
some of your computing needs to a company such as Google: they pay the cost of
developing the software and keeping it up-to-date and they earn back
the money to do this through advertising and other paid-for services.
What makes cloud computing different?
It's managed
Most importantly, the service you use is provided by someone else and
managed on your behalf. If you're using Google Documents, you don't
have to worry about buying umpteen licenses for word-processing
software or keeping them up-to-date. Nor do you have to worry
about viruses that might affect your computer or about backing up the
files you create. Google does all that for you.
One basic principle of cloud computing is that you no longer need to worry how the service
you're buying is provided: with Web-based services, you simply concentrate on whatever
your job is and leave the problem of providing dependable
computing to someone else.
It's "on-demand"
Cloud services are available on-demand and often bought on a "pay-as-you go" or
subscription basis. So you typically buy cloud computing the same way
you'd buy electricity, telephone services, or Internet access from a
utility company. Sometimes cloud computing is free or paid-for in
other ways (Hotmail is subsidized by advertising, for example).
Just like electricity, you can buy as much or as little of a cloud computing service as you need from
one day to the next. That's great if your needs vary unpredictably:
it means you don't have to buy your own gigantic computer
system and risk have it sitting there doing nothing.
It's public or private
Now we all have PCs on our desks, we're used to having complete control over
our computer systems—and complete responsibility for them as well. Cloud computing changes all that. It comes in two basic flavors, public and private, which are the cloud equivalents of the Internet and Intranets. Web-based email and free services like the ones Google provides are the most familiar examples
of public clouds. The world's biggest online retailer, Amazon, became
the world's largest provider of public cloud computing in early 2006. When
it found it was using only a fraction of its huge, global, computing power, it started
renting out its spare capacity over the Net
through a new entity called Amazon Web Services.
Private cloud computing works in much the same way but you access the resources you use
through secure network connections, much like an Intranet. Companies such as Amazon also
let you use their publicly accessible cloud to make your own secure private cloud,
known as a Virtual Private Cloud (VPC), using virtual private network (VPN) connections.
Types of cloud computing
IT people talk about three different kinds of cloud computing, where different
services are being provided for you. Note that there's a certain amount of vagueness
about how these things are defined and some overlap between them.
- Infrastructure as a Service (IaaS) means you're buying access to raw computing
hardware over the Net, such as servers or storage. Since you buy what you need and pay-as-you-go, this is often referred to as utility computing. Ordinary web hosting is a simple example of IaaS: you pay a monthly subscription or a per-megabyte/gigabyte fee to have a hosting company serve up files for your website from their servers.
- Software as a Service (SaaS) means you use a complete application running on
someone else's system. Web-based email and Google Documents are perhaps the best-known examples. Zoho is another well-known SaaS provider offering a variety of office applications online.
- Platform as a Service (PaaS) means you develop applications using Web-based tools so they run on systems software and hardware provided by another company. So, for example, you might develop your own ecommerce website but have the whole thing, including the shopping cart, checkout, and payment mechanism running on a merchant's
server. Force.com (from salesforce.com) and the Google App Engine are examples of PaaS.
Advantages and disadvantages of cloud computing
What's good and bad about cloud computing?
Advantages
The pros of cloud computing are obvious and compelling. If your business is selling
books or repairing shoes, why get involved in the nitty gritty of
buying and maintaining a complex computer system? If you run an
insurance office, do you really want your sales agents wasting time
running anti-virus software, upgrading word-processors, or worrying
about hard-drive crashes? Do you really want them cluttering your
expensive computers with their personal emails, illegally shared MP3 files,
and naughty YouTube videos—when you could leave that responsibility
to someone else? Cloud computing allows you to buy in only the
services you want, when you want them, cutting the upfront capital costs of
computers and peripherals. You avoid equipment going out of date and
other familiar IT problems like ensuring system security and reliability.
You can add extra services (or take them away) at a moment's notice as your business needs change.
It's really quick and easy to add new applications or services to your
business without waiting weeks or months for the new computer (and
its software) to arrive.
Drawbacks
![Apple ][ microcomputer in a museum glass case](http://cdn.explainthatstuff.com/appleII.jpg)
Instant convenience comes at a price. Instead of purchasing computers and software, cloud
computing means you buy services, so one-off, upfront capital
costs become ongoing operating costs instead. That might work out
much more expensive in the long-term.
If you're buying in services, you can buy only what people are providing, so you may be restricted
to off-the-peg solutions rather than ones that precisely meet your needs. Critics charge that
cloud-computing is a return to the bad-old days of mainframes and
proprietary systems, where businesses are locked into unsuitable, long-term
arrangements with big, inflexible companies. Instead of using
"generative" systems (ones that can be added to and extended in exciting ways
the developers never envisaged), you're effectively using "dumb terminals" whose uses are severely
limited by the supplier. Good for convenience and security, perhaps, but what
will you lose in flexibility? And is such a restrained approach good for the future
of the Internet as a whole? (To see why it may not be, take a look at Jonathan Zittrain's eloquent book
The Future of the Internet—And How to Stop It.)
Think of cloud computing as renting a fully serviced flat instead of buying a home of your
own. Clearly there are advantages in terms of convenience, but
there are huge restrictions on how you can live and what you can alter. Will
it automatically work out better and cheaper for you in the long term?
Photos: Cloud computing: forward to the future... or back to the past? In the 1970s, the Apple ][ became the world's first, bestselling small business computer thanks to a killer-application called VisiCalc, the first widely available computer spreadsheet. It revolutionized business computing, giving middle managers the power to crunch business data on their desktops, all by themselves, without relying on slow, centralized computer departments or bought-in data processing. Critics are concerned that cloud computing could be disempowering—a throwback to the 1970s world of centralized, proprietary computing.
In summary
Pros
- Lower upfront costs and reduced infrastructure costs.
- Easy to grow your applications.
- Only pay for what you use.
- Everything managed under SLAs.
- Overall environmental benefit (lower carbon emissions) of many users efficiently sharing large systems.
Cons
- Higher ongoing operating costs. Could they work out more expensive?
- Greater dependency on service providers. Can you get problems resolved quickly, even with SLAs?
- Risk of being locked into proprietary or vendor-recommended systems? How easily can you migrate to
another system or service provider if you need to?
- What happens if your supplier suddenly decides to stop supporting a product or system you've come to depend on?
- Potential privacy and security risks of putting valuable data on someone else's system in an
unknown location?
- If lots of people migrate to the cloud, where they're no longer free to develop neat and whizzy new things, what does that imply for the future development of the Internet?