When Microsoft announced its plans to build a brand-new hypervisor into a future version of Windows Server, it seemed to me that a much simpler path to baking virtualization into Windows would be to join the ranks of vendors developing and shipping products around the open-source Xen hypervisor project. Microsoft must have judged that relying on an outside source—and a GPL-licensed one, at that—for a piece of technology as central as a hypervisor would be too risky or uncomfortable, leading the Redmondians to opt instead to go it alone. However, as the slipping ship dates for Microsoft's home-baked hypervisor, Viridian, demonstrate, rolling a new hypervisor is no small task. What's more, once Viridian does go live, the difficulty of convincing customers to entrust production machines to an unproven new technology threatens to stall unacceptably Microsoft's virtual ambitions. Enter Citrix, which followed in a long tradition of making technology bets on Microsoft's behalf by announcing an acquisition of XenSource, the company started by the founders of the Xen project to commercialize the technology. While I typically associate Xen with Linux—since Linux is the platform on which Xen was born and on which Xen is most often deployed—the folks at XenSource have their aim focused most keenly on Windows. On the Citrix investor call this morning, XenSource President and CEO Peter Levine, summed that focus up well, "Our product focus is to provide the best Microsoft Windows virtualization experience on the market." For Citrix, the move means entry into the server virtualization space, as well as a rather prominent seat at the open-source community table. The XenSource purchase is akin to the big leap into the Linux community that Novell undertook when it purchased Ximian and SUSE back in 2003. As with Novell's Linux pickups, the biggest impact of the Citrix deal for XenSource will be the broadened customer reach that the company's Xen-based products will enjoy, as they tap into the Citrix network of some 5,000 channel partners. Also like the Novell/Linux deal, the Citrix move will probably spur concern from some that the open-source Xen might start moving in a less open direction. So far, however, the new partners seem to be saying the right things. The press release heralding the acquisition notes:
""Under Peter's leadership, Citrix is also committed to maintaining and growing its support for the Xen open-source community, led by XenSource co-founder and Xen project leader, Ian Pratt. Between now and the close of the acquisition, XenSource will work with the key contributors to the Xen project to develop procedures for independent oversight of the project, ensuring that it continues to operate with full transparency, fairness and vendor neutrality—principles that are critical to the continued role of Xen as a freely available open-source industry standard for virtualization.""For now, I don't see a reason to doubt Citrix's intentions, as it's the ecosystem that's sprouted up around Xen, including buy-in from large open-source oriented outfits such as Red Hat, Novell, and Sun; smaller proprietary software vendors such as Virtual Iron and 3Tera; hardware makers such as AMD and Intel; and from a host of non-commercial projects, that has built Xen into the promising rival to virtualization's current king, VMware, that Xen is today.