Cloud computing – A simple introduction – Explain that Stuff

by Chris Woodford. Last updated: March 19, 2017.

History has a funny way of repeating itself, or so they say. But it may come as some surprise to find this old clich applies just as much to the history of computers as to wars, revolutions, and kings and queens. For thelast 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 yourcompany needed sales or payroll figures calculating in a hurry, you'dmost likely have bought in "data-processing" servicesfrom another company, with its own expensive computer systems, thatspecialized in number crunching; these days, you can do the jobjust as easily on your desktop with off-the-shelf software. Or canyou? In a striking throwback to the 1970s, many companies arefinding, once again, that buying in computer services makes morebusiness sense than do-it-yourself. This new trend is called cloudcomputing and, not surprisingly, it's linked to the Internet'sinexorable rise. What is cloud computing? How does it work? Let'stake a closer look!

Photo: Cloud computing: the hardware, software, and applicationsyou're using may be anywhere up in the "cloud." As long as it all does what you want, you don't needto worry where it is or how it works.

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'sprovided for you as a service by another company and accessedover the Internet, usually in a completely seamless way. Exactlywhere the hardware and software is located and how it all worksdoesn't matter to you, the userit's just somewhere up in thenebulous "cloud" that the Internet represents.

Cloud computing is a buzzword that means different things to different people. For some, it's justanother way of describing IT (information technology) "outsourcing";others use it to mean any computing service provided over theInternet or a similar network; and some define it as any bought-in computerservice you use that sits outside your firewall. However wedefine cloud computing, there's no doubt it makes most sense when westop talking about abstract definitions and look at some simple, realexamplesso let's do just that.

Screenshot: Soundcloudone of my favorite examples of a website (and mobile app) that uses cloud computing to good effect. Musicians and DJs upload their music, which "followers" can listen to (or preview) for free through real-time streaming. You can build up a personal collection of tracks you like and access them from any device, anytime, anywhere. The music you listen to stays up in the cloud: in theory, there is only ever one copy of every music file that's uploaded. Where is the music stored? No-one but Soundcloud needs to knowor care.

Most of us use cloud computing all day long without realizing it. When you sit atyour PC and type a query into Google, the computer on your desk isn'tplaying much part in finding the answers you need: it's no more thana messenger. The words you type are swiftly shuttled over the Net toone 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 Googlesearch, the real work in finding your answers might be done by acomputer sitting in California, Dublin, Tokyo, or Beijing; you don't knowand 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 thenWeb-based services such as Hotmail came along and carried email offinto the cloud. Now we're all used to the idea that emails can bestored and processed through a server in some remote part of the world, easilyaccessible from a Web browser, wherever we happen to be. Pushing email off intothe 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 toa web-based service such as Google Documents and you cancreate a document, spreadsheet, presentation, or whatever you like usingWeb-based software. Instead of typing your words into a program like Microsoft Word orOpenOffice, 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 anyInternet-connected computer, anywhere in the world, any time you like. Do you knowwhere it's stored? No! Do you care where it's stored? Again, no! Using a Web-basedservice like this means you're "contracting out" or "outsourcing"some of your computing needs to a company such as Google: they pay the cost ofdeveloping the software and keeping it up-to-date and they earn backthe money to do this through advertising and other paid-for services.

"You don't generate your own electricity. Why generate your own computing?"

Jeff Bezos, Amazon.

Most importantly, the service you use is provided by someone else andmanaged on your behalf. If you're using Google Documents, you don'thave to worry about buying umpteen licenses for word-processingsoftware or keeping them up-to-date. Nor do you have to worryabout viruses that might affect your computer or about backing up thefiles 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 whateveryour job is and leave the problem of providing dependablecomputing to someone else.

Cloud services are available on-demand and often bought on a "pay-as-you go" orsubscription basis. So you typically buy cloud computing the same wayyou'd buy electricity, telephone services, or Internet access from autility company. Sometimes cloud computing is free or paid-for inother 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 fromone day to the next. That's great if your needs vary unpredictably: it means you don't have to buy your own gigantic computersystem and risk have it sitting there doing nothing.

Now we all have PCs on our desks, we're used to having complete control overour computer systemsand 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 examplesof public clouds. The world's biggest online retailer, Amazon, becamethe world's largest provider of public cloud computing in early 2006. Whenit found it was using only a fraction of its huge, global, computing power, it started renting out its spare capacity over the Netthrough a new entity called Amazon Web Services (AWS). Private cloud computing works in much the same way but you access the resources you usethrough secure network connections, much like an Intranet. Companies such as Amazon alsolet 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.

IT people talk about three different kinds of cloud computing, where differentservices are being provided for you. Note that there's a certain amount of vaguenessabout how these things are defined and some overlap between them.

What's good and bad about cloud computing?

The pros of cloud computing are obvious and compelling. If your business is sellingbooks or repairing shoes, why get involved in the nitty gritty ofbuying and maintaining a complex computer system? If you run aninsurance office, do you really want your sales agents wasting timerunning anti-virus software, upgrading word-processors, or worryingabout hard-drive crashes? Do you really want them cluttering yourexpensive computers with their personal emails, illegally shared MP3 files,and naughty YouTube videoswhen you could leave that responsibilityto someone else? Cloud computing allows you to buy in only theservices you want, when you want them, cutting the upfront capital costs of computers and peripherals. You avoid equipment going out of date andother 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 yourbusiness without waiting weeks or months for the new computer (andits software) to arrive.

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 disempoweringa throwback to the 1970s world of centralized, proprietary computing.

Instant convenience comes at a price. Instead of purchasing computers and software, cloudcomputing means you buy services, so one-off, upfront capitalcosts become ongoing operating costs instead. That might work outmuch more expensive in the long-term.

If you're using software as a service (for example, writing a report using an online word processor or sending emailsthrough webmail), you need a reliable, high-speed, broadband Internet connectionfunctioning the whole time you're working. That's something we take for granted in countries such as the United States, but it's much more of an issue in developing countries or rural areas where broadband is unavailable.

If you're buying in services, you can buy only what people are providing, so you may be restrictedto off-the-peg solutions rather than ones that precisely meet your needs.Not only that, but you're completely at the mercy of your suppliers if they suddenlydecide to stop supporting a product you've come to depend on.(Google, for example, upset many users when it announced in September 2012 that its cloud-based Google Docs would drop support for oldbut de facto standard Microsoft Office file formats such as .DOC, .XLS, and .PPT, giving a mere one week's noticeof the changealthough, after public pressure, it later extended the deadlineby three months.) Critics charge that cloud-computing is a return to the bad-old days of mainframes andproprietary systems, where businesses are locked into unsuitable, long-termarrangements with big, inflexible companies. Instead of using"generative" systems (ones that can be added to and extended in exciting waysthe developers never envisaged), you're effectively using "dumb terminals" whose uses are severelylimited by the supplier. Good for convenience and security, perhaps, but whatwill you lose in flexibility? And is such a restrained approach good for the futureof the Internet as a whole? (To see why it may not be, take a look at Jonathan Zittrain's eloquent bookThe Future of the InternetAnd How to Stop It.)

Think of cloud computing as renting a fully serviced flat instead of buying a home of yourown. Clearly there are advantages in terms of convenience, butthere are huge restrictions on how you can live and what you can alter. Willit automatically work out better and cheaper for you in the long term?

We've just had a quick and simple sketch of cloud computingand if that's allyou need, you can stop reading now. This section fills in some of the details, asks some deeper questions,looks at current trends, such as the shift to mobile devices, and explores challenging issues like privacy and security.

The figures speak for themselves: in every ITsurvey, news report, and pundit's op-ed, cloud computing seems theonly show in town. Back in 2008, almost a decade ago, the PewInternet project reported that 69 percent of all Internet users had"either stored data online or used a web-based softwareapplication" (in other words, by their definition, used some formof cloud computing). In 2009, Gartner priced the value of cloudcomputing at $58.6 billion, in 2010 at $68.3 billion, and in 2012 atover $102 billion. In 2013, management consultants McKinsey andCompany forecast cloud computing (and related trends like big data,growing mobilization, and the Internet of Things) could have a"collective economic impact" of between $1020 trillion by 2025.In 2016, Amazon revealed that its AWS offshoot, the world's biggest provider of cloud computing, is now a $10 billion-a-year business;the Microsoft Cloud isn't far behind.

So the numbers keep on creeping up and it's anexciting trend, to be sure. But there's one important word ofcaution: how you measure and forecast something as vague as "thecloud" depends on how you define it: if the definition keepsexpanding, perhaps that's one reason why the market keeps expandingtoo? Way back in the 1990s, no-one described Yahoo! Mail or Hotmailas examples of cloud computing, Geocities was simply a community ofamateur websites, and Amazon and eBay were just new ways of findingand buying old stuff. In 2010, in its breathless eagerness to talk upcloud computing, the Pew Internet project had rounded up everyweb-based service and application it could think of and fired it tothe sky. WordPress and Twitter were examples of cloud blogging,Google Docs and Gmail were cloud-based, and suddenly so too wereYahoo! Mail, buying things from eBay and Amazon, and even (bizarrely)RSS feeds (which date back to the late 1990s). Using "the cloud"as a loose synonym for "the Web," then expressing astonishmentthat it's growing so fast seems tautologous at best, since we knowthe Internet and Web have grown simply by virtue of having moreconnected users and more (especially more mobile) devices. Accordingto Pew, what these users prized were things like easy access toservices from absolutely anywhere and simple data storing or sharing.This is a circular argument as well: one reason we like "the cloud"is because we've defined it as a bunch of likeable websitesFacebook,Twitter, Gmail, and all the rest.

Businesses have shrewder and more interestingreasons for liking the cloud. Instead of depending on MicrosoftOffice, to give one very concrete example, they can use free,cloud-based open-source alternatives such as Google Docs. So thereare obvious cost and practical advantages: you don't have to worryabout expensive software licenses or security updates, and your staffcan simply and securely share documents across business locations(and work on them just as easily from home). Using cloud computing torun applications has a similarly compelling business case: you canbuy in as much (or little) computing resource as you need at anygiven moment, so there's no problem of having to fund expensiveinfrastructure upfront. If you run something like an ecommercewebsite on cloud hosting, you can scale it up or down for the holidayseason or the sales, just as you need to. Best of all, you don't needa geeky IT department becausebeyond commodity computers runningopen-source web browsersyou don't need IT.

When we say cloud computing is growing, do we simply meanthat more people (and more businesses) are usingthe Web (and using it to do more) than they used to? Actually we doand that's why it'simportant not to be too loose with our definitions. Cloud web hostingis much more sophisticated than ordinary web-hosting, for example,even thoughfrom the viewpoint of the webmaster and the personaccessing a websiteboth work in almost exactly the same way. Thisweb page is coming to you courtesy of cloud hosting where, a decadeago, it ran on a simple, standalone server. It's running on the sameopen-source Apache server software that it used then and you canaccess it in exactly the same way (with http and html). Thedifference is that it can cope with a suddenly spike in traffic inthe way it couldn't back then: if everyone in the United Statesaccessed this web page at the same time, the grid of servers hostingit would simply scale and manage the demand intelligently. The photosand graphics on the page (and some of the other technical stuff thathappens behind the scenes) are served from a cloud-based ContentDelivery Network (CDN): each file comes from a server in Washington, DC, Singapore,London, or Mumbai, or a bunch of other "edge locations," depending on where in the world you (the browser) happen to be.

This example illustrates three key points ofdifference between cloud-based services and applications and similarones accessed over the web. One is the concept of elasticity(which is a similar idea to scalability):a cloud service or application isn't limited to what a particularserver can cope with; it can automatically expand or contract itscapacity as needed. Another is the dynamic nature of cloudservices: they're not provided from a single, static server. A third,related idea is that cloud services are seamlesswhetheryou're a developer or an end user, everything looks the same,however, wherever, and with whatever device you use it.

Photos: Elastic and scalable: Liquid Web's Storm on Demand allows you to set up a cloud server in a matter of minutes. With a couple of mouse clicks, you can resize your server (upgrade or downgrade the memory, for example)to cope with changes in demandfor example, in the run up to a Black Friday sale. Every aspect of the service is pay-as-you-go. It's easy to use even if you have little or no experience of setting up or managing dedicated servers.

One of the biggest single drivers of cloudcomputing is the huge shift away from desktop computers to mobiledevices, which (historically, at least) had much less processingpower onboard. Web-connected smartphones, tablets, Kindles, and othermobile devices are examples of what used to be called "thinclients" or "network computers" because they rely on theservers they're connected to, via the network (usually the Internet),to do most of the work. A related trend referred to as bring yourown device (BYOD) reflects the way that many companies now allowtheir employees to logon to corporate networks or websites usingtheir own laptops, tablets, and smartphones.

From the smartphone in your pocket to the mythicalfridge that orders your milk, the number and range of devicesconnected to the Internet is increasing all the time. A new trendcalled the Internet of Thingsanticipates a massive increase inconnected devices as everyday objects and things with built-insensors (home heating controllers, home security webcams, and evenparcels in transit) get their own IP addresses and become capable ofsending and receiving data to anything or anyone else that's online.That will fuel the demand for cloud computing even more.

Photo: Mobile cloud: The shift to mobile devices and the growth of cloud computing are mutually reinforcing trends. Mobile devices are much more useful thanks to cloud-based apps like these, provided by Google. In other words, one reason for buying a mobile is because of the extra (cloud-based) things you can do with it. But these services are also thriving because they have ever-increasing numbers of users, many of them on smartphones.

How significant is the shift to mobile? By anymeasurement, phenomenal and dramatic. Bearing in mind that there wasonly one functioning mobile phone in 1973 when Martin Cooper made thefirst cellphone call, it's staggering to find that there are now anestimated 8 billion mobile subscriptions (more than one for everyperson on the planet). By 2012, Goldman Sachs was telling us that 66percent of Net-connected devices were mobiles, compared to just 29percent desktops. Mobile Internet traffic finally overtook desktoptraffic in 2014/15, according to Comscore and, in response, Googlerolled out a "mobile-friendly" algorithm in 2015 to encouragewebmasters to optimize their sites so they worked equally well onsmartphones.

Cloud computing makes it possible for cellphonesto be smartphones and for tablets to do the sorts of things that weused to do on desktops, but it also encourages us to do more thingswith those devicesand so on, in a virtuous circle. For example, ifyou buy a smartphone, you don't simply do things on your phone thatyou used to do on your PC: you spend more time online overall, usingapps and services that you previously wouldn't have used at all.Cloud computing made mobile devices feasible, so people bought themin large numbers, driving the development of more mobile apps andbetter mobile devices, and so on.

Stare high to the sky and you can watch cloudsdrift by or, if you're more scientific and nuanced, start to teaseout the differences between cumulus, cirrus, and stratus. In much thesame way, computing aficionados draw a distinction between differenttypes of cloud. Public clouds are provided by people such asAmazon, Google, and IBM: in theory, all users share space and time onthe same cloud and access it the same way. Many companies, forexample, use Gmail to power their Internet mail and share documentsusing Google Drivein pretty much the same way that you or I mightdo so as individuals. Private clouds work technically the sameway but service a single company and are either managed exclusivelyby that company or by one of the big cloud providers on their behalf.They're fully integrated with the company's existing networks,Intranet, databases, and infrastructure, and span countries orcontinents in much the same way. Increasingly, companies find neitherof these bald alternatives quite fits the billthey need elementsof eachso they opt for hybrid clouds that combine the bestof both worlds, hooking up their existing IT infrastructure to apublic cloud system provided by someone like Amazon or Google. Othertrends to watch include the development of personal clouds,where you configure your own home network to work like a mini-cloud(so, for example, all your mobile devices can store and access filesseamlessly), and peer-to-peer cloud computing, in which thedynamic, scalable power of a cloud computing system is provided notby giant data centers but by many individual, geographicallydispersed computers arriving on the network, temporarily contributingto it, and then leaving again (as already happens with collaborativescience projects like SETI@home and

Security has always been an obvious concern forpeople who use cloud computing: if your data is remote and travelingback and forth over the Internet, what's to keep it safe? Perhapssurprisingly, many IT professionals think cloud-based systems areactually more secure than conventional ones. Ifyou're buying into Google's, Amazon's, or Microsoft's cloud-based services, you're also buyinginto world-class expertise at keeping data safe; could youor your ITteammanage security as well? Security can therefore be seen as acompelling reason to migrate to cloud-based systems rather than areason to avoid them.

Privacy is a more nuanced and complex issue. Whilewe all understand what we mean by keeping data secure, what do wemean by keeping it private in a world where users of cloud-basedservices like Twitter, Instagram, and Snapchat happily share anythingand everything online? One of the complications is so-called bigdata, the statistical ("analytic") information that companieslike Google and Facebook gather about the way we use theircloud-based services (and other websites that use those services).Google, for example, collects huge amounts of data through itsadvertising platforms and no-one knows exactly what happens to itafterward. Facebook knows an enormous amount about what people saythey "like," which means it can compile detailed profiles of allits users. And Twitter knows what you tweet, retweet, and favoritesoit has similar data to Facebook. The quid-pro-quo for "free"web-based services and apps is that you pay for what you use with aloss of privacy, typically to power targeted advertisements.

Another complication is that privacy meansdifferent things in different parts of the world. In Europe, forexample, the European Union has strict restrictions on how data canbe moved in bulk from one country to another or shared by companieslike Google that have multiple subsidiaries operating across countries andcontinents. While Internet-based cloud computing makes nationalboundaries obsolete, real-world laws still operate according toold-fashioned geographyand that could act as a serious brake onthe aspirations of many big cloud providers.

When it comes to the everyday web services we allenjoy, there may be different kinds of clouds on the horizon. Asweb-based advertising dwindles in effectiveness, one future concernmust be how companies like Google, Facebook, and Twitter willcontinue to fund their ever-growing, (essentially) cloud-based,services without using our data in increasingly dubious ways. Part ofthe reason for the huge growth in popularity of services like this issimply that they're free. Would Facebook be so popular if we had topay for it through a monthly subscription? If Google Docs cost money,would we slink back to our desktop PCs and Microsoft Word? Can advertising continue to sustain an ever-growing field of cloud-basedservices and apps as the number of Internet users and Net-connecteddevices continues to grow? Watch this space!

In theory, cloud computing is environmentally friendly because it uses fewer resources(servers, cooling systems, and all the rest) and less energy if 10 people share anefficiently run, centralized, cloud-based system than if each of them run their owninefficient local system. One hosting provider in the UK told me that his company hasembraced cloud systems because it means they can handle more customers on far fewerphysical servers, with big savings in equipment, maintenance, and energy costs.In theory, cloud computing should be a big win for the environment; in practice,it's not quite so simple.

Ironically, given the way we've defined cloud computing, it matters where your cloud serversare located and how they're powered. If they're in data centers powered by coal, instead of cleaner fuels such as natural gas or (better still) renewable energy, the overall environmental impact could be worse than your current setup. There's been a lot of debate about the energy use of huge data centers, partly thanks to Greenpeace highlighting the issue once a year since 2009. In its 2011 report[PDF] How Dirty is Your Data Center: A Look at the Energy Choices that Power Cloud Computing, it ranked cloud computing providers like Akamai and Amazon on eco-friendliness, alongside companies like Facebook, Google, and Twitter whose services are underpinned by a massive global network of data centers. By 2017, in a report calledClicking Clean, Greenpeace was congratulating around 20 of the biggest data center operators (including Apple, Facebook, and Google) for starting on the path toward 100 percent renewable energy. In the United States in particular, quite a few cloud (and web hosting) providers explicitly state whether their servers are powered by conventional or green energy, and it's relatively easy to find carbon-neutral service providers if that's an important factor for your business and its CSR (corporate social responsibility) objectives.

Chart: Growth in energy use in data centers from 2007 to 2013. Drawn by us using data from the 2012 study by DatacenterDynamics (DCD) Intelligence published in Computer Weekly, October 8, 2012. I've struggled to find figures for the years from 2014 onward; as soon as I do, I'll update the chart!

When it comes to overall impact on the planet, there's another issue to consider. If cloud services simply move things you would do in your own office or home to the cloud, that's one thing; the environmental impact merely transfers elsewhere. But a lot of cloud- and Internet-based services are encouraging us to use more computers and gadgets like iPads and iPhones for longer, spending more time online, and doing more things that we didn't previously do at all. In that sense, cloud computing is helping to increase global energy use and greenhouse gas emissions so describing it as environmentally friendly is highly misleading.That was evident from a 2012 study by DatacenterDynamics (DCD) Intelligence, the British Computer Society, and partners(reported in Computer Weekly), which showed that global energy use from data centers grew from 12 gigawatts (GW) in 2007 to 24GW in 2011 and predicted it would reach 43GW some time in 2013. However, a follow-up study revealed a significant slowing down of the rate of growth in cloud power consumption, from 19 percent in 2011/2 to around 7 percent in 2013. Growing concerns about the impact of cloud computing have also prompted imaginative new solutions.Later in 2013, for example, researchers at Trinity College Dublin and IBM announced they'd found a way to reduce cloud emissions by over 20 percent by using smart load balancing algorithms to spread out data processing between different data centers. Even so, with cloud computing predicted to become a $5 trillion business by 2020, power consumptionseems certain to go on increasing. Ultimately, the global environment, the bottomline trendever-increasing energy consumptionis the one that matters. It's no good congratulating yourself on switching to diet Cola if you're drinking four times more of it than you used to. In 2016, Peter Judge of DatacenterDynamics summed things up pithily: "No one talks much about total energy used by data centers because the figures you get for that are annoying, depressing and frustrating.... The truth is: data center power is out of control."

From Google searches to Facebook updates and super-convenient Hotmail, most of us value the benefits of cloud computing very highly, so the energy consumption of data centers is bound to increaseand ensuring those big, power-hungry servers are fueled by green energy will become increasingly important in the years to come.

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