The battle lines for 2008's virtualisation wars have now been drawn. Events over the last few weeks have combined to show us the weapons that the major virtualisation vendors are likely to be using over the next 12 months - with the major protagonists being VMware, Microsoft, Citrix - and now Oracle. So here's the current state of play.

Microsoft crashes in

Microsoft's recent announcement of Hyper-V - once codenamed Viridian - has officially set the cat among the pigeons. Following a painful development process that suffered from several delays, we're now told that Hyper-V is on track for delivery six months after Windows Server 2008 ships, in Standard, Enterprise, DataCenter, Web Server versions. That means next August at the latest.

Microsoft won't be gouging for its hypervisor technology. The price of WinServ08 will be barely more than that of its predecessor, Windows Server 2003, said Microsoft, and the cost of adding Hyper-V will be pretty small. Microsoft looks set to charge just US$28 for the hypervisor technology - WinServ08 will cost $971 for a five-client licence, non-hypervised version and just $28 more with Hyper-V. The differential remains the same as you add client licences, and it doesn't matter from a price point of view how many CPUs you run it on.

There was little else Microsoft could do, given that VMware has such an overwhelming share of the market, and that it provides a virtualisation product - VMware Server - for free.

We don't have a huge amount of detail about Hyper-V. It's directly comparable to VMware's ESX Server, so it offers hardware virtualisation - this is the fully leaded technology that allows a host to support any guest operating system.

Those offering para-virtualisation and OS-level virtualisation argue that there's a higher performance penalty to pay for hardware virtualisation, but the speed hit is lessening as processor designers build in increasing levels of support for the technology, and as hardware performance generally improves. The penalty is tangible but the benefits of flexibility are largely neutralising that argument, if VMware's continued grip on the virtualisation market is any indication of enterprise purchasing preferences.

And Microsoft is displaying its new, more open approach with the launch of Hyper-V too, insisting that it runs Linux very well. At the launch, server product VP Andrew Lees said: "We have very tight integration of running Linux on Windows. It [Linux] runs incredibly well." The rationale, said Less, was that if virtual Linux runs well on Windows, it will ultimately make more people choose Windows Server.

There are a couple of minor issues raised in the product's community technology preview release notes, namely that it won't load on a dynamic disk, and that performance is likely to be poor on a CPU with hyperthreading enabled. There remain a number of networking and storage issues too but you could expect these to be resolved by the time of the product's release.

However, it's clear that Microsoft believes that the product's differentiation will need to be more visible than that. Most observers expect the hypervisor to become close to ubiquitous and very cheap if not free over the short to medium term. This explains why VMware continues to keep its prices high for as long as it can - and why its recent VMworld love-in, in September in San Francisco, saw a huge focus on what VMware called datacentre orchestration.

In other words, the software that manages virtual machines en masse. It's all part of the general move towards a datacentre-wide operating system, as evidenced by VMware's announcement on the first day of VMworld of the purchase of Dunes Technologies, which it described as "a company that provides IT process orchestration software for virtual environments." VMware product VP Raghu Raghuram said in the announcement: "Dunes has developed a powerful orchestration platform that will allow us to automate the entire virtual machine lifecycle from requisition to de-commissioning."

As we noted at the time of Microsoft's announcement, Microsoft said that one it's going to try to beat VMware is by providing management tools that allow, for example, an administrator to quickly deploy another virtual server if one is backlogged with tasks. Its virtualisation tools will also allow a view into how the OSes and applications are performing and allow modifications, said Lees. More details on that as we get them.

The rise and rise of Citrix

One area that enterprise market leader VMware has yet to conquer however is desktop virtualisation. There are many thousand times more desktops than servers out there, a much bigger market, and one in which VMware has nowhere near the dominance as it does in enterprise servers. As a result, others have decided to attack those areas, notably Parallels, which has made a considerable impact in bringing virtualisation - and so the ability to run PC-based applications - to the Apple Mac desktop.

However, from an enterprise perspective, the main player in this market has, for around a decade, been Citrix, which has faced disturbingly few challengers to the dominance of its application delivery platform in the shape of Presentation Server. This allows enterprises to host OS and applications in a server at the back end and push the desktop image down the wire to a thin client.

The issues there are the need for a pretty meaty server, and the fact that not all data types or applications respond well to being detached from the screen. Data-heavy, time-sensitive applications suffer most so wheel on the usual candidates: video and 3D graphics.

But Citrix has shaken off a lot of that baggage off its shoes with the acquisitions of XenSource, for its virtualisation technology, and of Ardence for its desktop image distribution capabilities. Many are now looking at Citrix in a new light, especially since the company made much of the fact that it was virtualisation technology-agnostic - a stance that will have changed within the company, no matter what its protestations to the contrary.

Interestingly, since Citrix is now in the business of competing with VMware, as does Microsoft, the two companies, who have long shared a technology alliance, seem likely to grow closer. This must have come as a bit of a shock to VMware, since Citrix was using some of VMware's technology for its desktop VMs. Those days are over, as industry observer Brian Madden pointed out. He noted that: "In the five hours of keynotes over two days at Citrix's App Delivery Expo [last month], the word 'VMware' was not mentioned once. Not one single time."

VMware continues to view Citrix as a partner however, as this snippet from its website demonstrates: "VMware and Citrix have worked to deliver a highly reliable, interoperable and manageable server and client consolidation solution that helps remote offices and clients simplify their IT environments and reduce desktop administration tasks by centralizing application delivery."

VMware motors on

Meanwhile, VMware glides smoothly on, if the money-men are to be believed.

With virtualisation proving to be the hottest technology in the back-office today - if not in enterprise IT generally - it's not surprising that VMware continues to be the stock market's darling. Although the announcement this week that Oracle will be joining the virtualisation fray did depress VMware's valuation slightly, the share price rebounded on the launch of VMware Server 2.0, which includes support inter alia for Microsoft Vista. Shares are now floating at around three times their price at the time of the IPO, giving the company a much bigger market cap than much bigger and longer-established IT equipment vendors.

However, as many top execs will admit, albeit quietly and with a glass of wine inside them, stock market evaluations bear only a passing resemblance to reality. From the stock market's point of view, VMware owns the enterprise virtualisation space - which remains where the big money is, since the drivers are so clear - take-up is growing, and there's huge potential for expansion. They've discounted MS's heavily-trailed entry into the market because - probably correctly - Microsoft gets it right on the third iteration of a technology. Whether that will hold true for Hyper-V remains to be seen.

But growing competition is what VMware faces, along with the commoditisation of its core technology; pretty soon you'll find it installed in the firmware of most servers as a BIOS option. This is why VMware is moving into virtual machine and datacentre automation, and why VMworld was stuffed with virtualisation system management vendors. They all smell the opportunity too.

VMware reckons it's not fazed. One news story reported spokesman Richard Garsthagen saying that VMware was focusing "far beyond the virtualisation layer by addressing and solving business problems with applications that are built on top of the virtualisation layer."

VMware says it'll continue to fight back by moving the technology on - which, if past policies continue, is likely to mean a combination of in-house development and acquisition of its eco-system partners. Meanwhile, those who don't move fast enough to develop new products and features will be crushed under its tank tracks as product feature sets expand.

Until now, VMware hasn't had to face determined opposition. Now there's a pincer movement going on: Citrix and Microsoft are attacking the desktop and enterprise server markets.

There's also a fair degree of noise and harassment from smaller players such as SWsoft. And Oracle's announcement this week of its entry into the virtualisation market using Xen technology shouldn't be entirely discounted either - although it's likely to be less successful than its hopes because of fragmentation.

As one VMware spokesman pointed out: "There are at least five variants of Xen available to customers today. Oracle's will be the sixth." There's more reaction on Oracle's move here.

But next year, as products mature and are deployed in the real world, we'll get a clearer idea of just what those battle lines consist of.