Sam Johnston's Blog

There's been a good deal of confusion of late between the general concept of cloud computing, which I define as "Internet ('Cloud') based development and use of computer technology ('Computing')", and its various components (autonomic, grid & utility computing, SaaS etc.). Some of this confusion is understandable given issues get complex quickly when you start peeling off the layers, however much of it comes from the very same opportunistic hardware & software vendors who somehow convinced us years ago that clusters had become grids. These same people are now trying to convince us that grids have become clouds in order to sell us their version of a 'private cloud' (which is apparently any large, intelligent and/or reliable cluster).

Let's not forget that much of the value of The Cloud (remember, like the Highlander "there can be only one") comes from characteristics that simply cannot be replicated internally, like not having to engineer for peak loads and being able to build on top of the ecosystem's existing services. Yes, you can build a cloud computing architecture with large, intelligent clusters that are a second rate citizens or 'clients' of The Cloud (as most of these 'private clouds' will be) but calling them 'clouds' is a stretch at best and deceptive at worst - let's call a spade a spade shall we.

The Cloud is what The Grid Could have been

The term 'Grid' was coined by the likes of Ian Foster in the 90's to define technoloies that would 'allow consumers to obtain computing power on demand', following on from John McCarthy's 1960 prediction that 'computation may someday be organized as a public utility'. While it is true that much of the existing cloud infrastructure is powered by large clusters (what these vendors call grids) there are some solid, successful counterexamples including:

• BitTorrent which shares files between a 'cloud' of clients
• SETI which distributes computational tasks between volunteers
• Skype which has minimal centralised infrastructure for tasks like account creation and authentication, delegating what they can to 'supernode' clients

By focusing on batched computational workloads and maximizing peak processing performance rather than efficiently servicing individual requests, grid computing has painted itself into a corner (or at least solves a different set of problems) thus creating a void for The Cloud to fill.

The Cloud is like the electrivity network, only photons are more convenient than electrons so the emergence of a single global provider is a possibility, some would say a threat.

Perhaps Thomas J. Watson Sr. (then president of IBM) was right when he was famously [mis]quoted as predicting a worldwide market for 5 computers back in 1943. On one hand, without the physical constraints of electrons (eg attenuation, crosstalk) it is concievable that our needs could be serviced by photons channeled over fiber optic to one massive, centralised computing fabric. We don't have national water grids simply because water is too heavy and even electrons get unmanageable on this scale (though many problems were solved by standardising and moving to alternating current), but weightless photons have no such limitation. At the other end of the scale we distribute the load across relatively tiny devices which may well outnumber their masters (pun intended). The reality will almost certainly fall somewhere in between, perhaps not too far from what we have today: a handful of global providers, scores of regional outfits and then the army of niche players. The forces of globalization, unusually free of geographic constraints, will also certainly affect how this plays out by drawing in providers from emerging economies.

The Cloud equivalent of an electron could be a standardized workload consisting of a small bundle of (encrypted) data and the code required to perform an action upon it.