Citrix has begun shipping its new software for delivering virtualized Windows desktops to thin clients running Linux, Windows CE, Windows XP Embedded, and other operating systems. XenDesktop dynamically assembles a “pristine, high-performing desktop,” with personalized applications and settings, every time a user logs on, says… Citrix.

Desktop virtualization, the most well-known example of which has been VMWare's Virtual Desktop Infrastructure (VDI), has been steadily gaining traction as a new way of delivering Windows desktops to thin client devices, such as those connected via Microsoft's RDP (remote desktop protocol) or Citrix's ICA (independent computing architecture). In traditional thin client architecture, available ever since the 1998 release of Windows NT 4.0 Terminal Server, users log on to a host computer whose physical resources — memory, storage, processor cycles, etc. — are being shared with others at the operating system level. Examples include Windows Server 2008 or Citrix's XenApp (formerly known as MetaFrame and Presentation Server). With desktop virtualization, on the other hand, the host's resources are divided up by hypervisor software, which creates a virtual machine (VM) for each user.

With VM technology, a separate instance of an operating system — usually Windows XP — exists for each user, whose thin client is then connected to it via RDP or ICA, just as in the past. Virtualization makes a much greater degree of personalization possible, and also allows backing up VMs and moving them from server to server if necessary.

But, says Citrix — which acquired hypervisor vendor XenSource last year — VM technology has carried some disadvantages with it. Namely, since each user can have their own operating system and applications, storage requirements can be extensive, and administrators must make the rounds virtually, if not physically, to apply software patches.

Citrix's XenDesktop delivers a “pristine, personalized” operating system image when users log on
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Now, claims the company, XenDesktop provides the best of both worlds. It employs the XenSource hypervisor technology and uses one easily-managed core operating system image, maintained separately from any end user applications or preferences. When users log on, a virtual machine is dynamically created that includes any previously applied personalizations. As for applications, these are delivered “only as needed and in the most appropriate way as isolated, de-coupled elements on top of the standard core operating system,” says Citrix.

The process sounds as though it could take as long as — if not longer than — booting a traditional PC. Not so, according to Citrix. Virtual desktops are significantly faster to start up and provide users with an “instant on” experience, it's claimed. They can also be accessed remotely via low-bandwidth or high-latency WAN connections when necessary.

Citrix XenDesktop is compatible with all major thin client products, whether based on Windows CE, Windows XP Embedded, or Linux. It also supports any VM server infrastructure, including Microsoft's forthcoming Hyper-V, and VMware's ESX, says Citrix.

Further information

Citrix XenDesktop is available now, in five versions. A downloadable “Express” edition is free, and can be used by up to 10 users to test Citrix's Desktop Delivery Controller and virtual machine infrastructure. A “Standard” edition, suitable for up to 100 users, adds secure remote access and is priced at $75 per virtual desktop per year. An “Advanced” edition, with desktop provisioning and resource pooling, supports an unlimited number of users at $195 per virtual desktop per year. An “Enterprise” edition adds integrated application delivery, at an annual cost of $295. A “Platinum” edition adds performance monitoring and WAN optimization, at an annual cost of $395.

The Express edition can be downloaded from the company's website, here.

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