Xen

Acquired for $500 million last year, a start-up that grew from research in the Computer Laboratory has just seen its first products being launched under the Citrix brand name.

Our aim was to build a global commercial grid that would suit the dynamic and secure requirements of its users.

Dr Ian Pratt

A vision of how computers around the world could be used more efficiently through ‘virtualisation’ set a group of researchers in the Computer Laboratory on the trail of how best to deliver this technology. ‘Our aim was to build a global commercial grid that would suit the dynamic and secure requirements of its users,’ explained Dr Ian Pratt, who led the team. A decade later, the start-up company this yielded, XenSource, was acquired by Citrix for $500 million and, a few weeks ago, the first Xen-based Citrix products were released.

The researchers’ original ideas and scale of delivery for virtualisation were ambitious. ‘Back then it was considered too radical to be funded,’ said team-member Dr Steve Hand. The essential kick-start came when PhD student Keir Fraser decided to build the key component, a virtual machine monitor called a hypervisor. ‘This was crucial since it provided a new level of operation: it was an umbrella under which many different operating systems could work, allowing users to run their own operating system and applications within,’ said Dr Hand. ‘What we were doing was breaking the link between software and hardware in a safe and secure way,’ explained Dr Pratt.

The turning point came in 2002 when funding was secured from the Engineering and Physical Sciences Research Council (EPSRC) and the team published a seminal paper that is still one of the most widely cited articles in the field.

But just as importantly, the researchers released the software as open source under the GNU General Public License – anyone in the world now had the opportunity to use it free of charge. This turned out to be integral to the success of Xen. ‘It allowed an enormous and growing academic and business community to work with the software. As Xen evolved, it was fed partly by the community that was using it,’ said Dr Hand. With $6 million funding from Silicon Valley, Drs Pratt, Hand, Fraser and Christian Limpach formed the start-up company XenSource, whose acquisition by Citrix was finalised late last year.

‘Research at the Computer Laboratory has a tradition of building something new from the ground up. These strengths gave us the resilience and expertise we needed to accomplish this,’ said Dr Hand. Following the acquisition by Citrix, what’s next for Xen? ‘Xen for laptops and desktops…We’d love to see not only Xen on every server but Xen on every laptop and every mobile phone!’ said Dr Pratt.

For more information, please contact Citrix (www.citrix.com) or Dr Steve Hand (Steven.Hand@cl.cam.ac.uk).

 


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