When you know the Sun is at the centre of the solar system, any other model of the solar system looks insane. But if you do not know, and you have no means other than the naked eye to observe the motion of the planets, the structure of the solar system is neither obvious nor easy to deduce. Only seven heavenly bodies (Sun, Moon, Mercury, Venus, Mars, Jupiter and Saturn) are visible to the naked eye. If you put the Earth at the centre of all these ‘planets’, then the planets appear to make very strange orbits around the earth. In about AD 141, Ptolemy proposed a model based on such observations to explain planetary motion and it dominated European thinking for more than a thousand years. Here it is:

The Ptolemaic (Geocentric) Solar System

According to this model, both the Sun and Moon orbited the Earth. Venus and Mercury had orbits that centred on a line drawn from the Earth to the Sun and thus they were always fairly close to the Sun. The outer planets, Mars, Jupiter and Saturn, each revolved around a point that itself orbited the Earth. The Moon was closest to the earth, followed by Mercury, Venus, the Sun, Mars, Jupiter and Saturn – in that order. Although a heliocentric model was proposed many times before Copernicus, it was never popular. The Copernican model itself was only accepted by virtue of Galileo’s telescope. Facts rather than rational argument destroyed the Ptolemaic model.

The PC-Centric Desktop v the Server-Centric Desktop

A similar conceptual battle has been taking place in the IT world, for about a decade, between the PC-centric desktop and the server-centric desktop. These two models came into existence primarily because of market pressures. The early years of computing were necessarily server centric or, to be more accurate, mainframe centric. Computing resources were scarce and had to be shared in an organized way. When the PC emerged, the users got their own resource and, for a while, gloried in it. And as the PC evolved, the PC became the centre of the IT universe.

The two models of computing are distinctly different. The server-centric model sees the corporate network as a shared resource space that can best be managed centrally. The PC-centric model views the corporate network as a series of equal domains that interact in a peer-to-peer manner, with each domain managed locally. Applications are viewed as belonging to the PC, with the rest of the network revolving around its operation.

Ptolemy and the PC

Simple parallels can be drawn between the PC-centric approach to corporate computing and the Ptolemaic model of the solar system. Both place the wrong object at the centre of the system and both become less and less coherent as the size of the whole system increases.

The PC put the users in control of their own domain. To a certain extent they became their own IT department with a degree of freedom to manage their domain and even choose or develop their own software. However, the task of management became too onerous. Software and data needed to be backed-up and where problems occurred the user had to recover the situation. To add to the problem, the PC environment was not static. Increases in CPU power led to regular hardware upgrades. PC applications had regular software upgrades. Further problems emerged with the advent of computer viruses (a PC phenomenon). There were standardisation problems, there were security issues, and the cost in both time and money was high.

The benefits that the PC delivered to the corporation were indisputable: word processing, spreadsheets, presentation software, PC databases and so forth – the office productivity applications. However, these applications did not integrate well, if at all, with server oriented applications. The cost of PC computing was high, but it was concealed. Few organizations even attempted to account for the user’s ‘PC management time’ or learning time. Few thought to put a cost to the lack of standardisation, or lack of availability.

Part of the software industry thrived on providing solutions to problems that existed entirely because of the PC-based approach to computing: virus checkers, file converters, uninstallers, disk defragmenters and so forth. Such utilities soon became necessary in the corporation to assist the user in managing the PC domain.

The Ptolemaic model of the solar system provides a parallel to some of this. The supporters of the model had difficulties in accounting for the exact orbits of the planets and explaining why they moved in such a way. In order to deal with these difficulties, they formulated the concept of the ‘primum mobile’ – an invisible body that caused the awkward motion of the planets. The primum mobile was a solution to a problem that existed entirely because of the Ptolemaic model. Expand the Ptolemaic model and you run into further problems. Trying adding moons to Mars, Jupiter and Saturn. Try accounting for the phases of Venus. The Ptolemaic model does not scale.

The Decline of PC-centric Computing

PC-centric computing within the corporation is in decline and has been for a while. Most of the organisations that made a virtue of PC computing have retreated to a more sensible regime that involves a balance between empowering the user and managing the network. However, in doing this they have not usually adopted a fully server-centric approach – they have continued with a compromise arrangement that de-emphasises the PC a little bit.

This is partly due to the fact that the technology to deliver true server-centric computing is still under development. Citrix provided a first-generation server sided option and still does – catering for both PCs and thin clients. Recently it snapped up Ardence, a start-up company with a streaming solution for PC usage (basically the Ardence software runs on a server and streams the image to the desktop). Another start-up, Softricity, did something similar, but at the application level rather than the OS level. They were also quickly snapped up, by Microsoft.

A more comprehensive solution is offered by a company called ClearCube. They provide both hardware and software to “virtualize” the desktop. With this approach, the pendulum swings back completely to sever-centric server-managed desktops. The ClearCube solution puts the whole PC on a blade, which lives in a blade cabinet – and when it’s not in use, the PC lives as a disk image within the network. This makes it possible to just provide screens and keyboards for the desktop, and fire up a PC only when it’s in use.

The “virtual PC” doesn’t have to take up a whole blade. It can run within a virtual machine on the blade, so that the blade could be running multiple PCs. With ClearCube, because of its proprietary technology, the blade can also deliver a virtual PC to anywhere in the world. So when American staff leave work, say, a blade boots up PCs for staff in India. Alternatively, the resources of the blade could be made available to a server grid.

Some users in the IT industry have always adhered to server-centric computing, as much as they could, both for the sake of economy and security – particularly security. The PC is a security nightmare for many reasons, almost all of which have to do with PC-centric operation. The financial sector and the defense sector have thus been enthusiastic adopters of ClearCube, and have long been heavy users of Citrix.

Recent figures indicate that the “virtual desktop” is starting to grow quickly (at 45% per annum). It becomes easy to understand why, when you start to make comparisons between PC Total Cost of Ownership (TCO) and “virtual PC” TCO. As a rough average, PC TCO per annum has been around 5
times the purchase cost of the PC for a decade. The 5 times multiple is a PC-centric overhead. It isn’t difficult to cut that cost in half with a server-centric “virtual PC” approach to the desktop, and it isn’t difficult to cut the cost to ribbons, if you’re a global operation.