The basic concept of virtualization is the ability for a server to run an environment on a platform other than the one on which it believes to be installed. The theoretical virtue of virtualization is that by unbinding software from hardware, you gain several new degrees of flexibility and control. Today, the new term for “virtual servers” is servers.
But this is not an article about the diametrical counterpart of that concept, the virtual client. That’s been done — some would say, more than the subject deserved. This article explains what is fast becoming an alternative concept of the entire network computing model, one in which the traditional hierarchical relationship of application to operating system to processor to device is being turned on its ear. Virtual Desktop Infrastructure (VDI) refers to a specific class of client-side virtualization. Essentially it is the capability for a server to compose the image of a usable computing environment, complete with installed applications, personalized user profiles, resource permissions, and policies, so that a remote user can engage and interact with that environment as though it existed physically someplace. It doesn’t really.
It’s Not a Desk, and It’s Not On Top, So What Is It?
Whether the VDI environment resembles Windows 7, Mac OS X, or Ubuntu or Mandriva or openSUSE Linux may not even be consequential. Conceivably the applications for any or all of these operating systems could run within the same environment; and in fact, there are open source developers who are aiming for that very goal. What’s important is that the user sees a desktop, and that it doesn’t look like one being served up remotely. The administrator, meanwhile, sees a single pool of resources that she does not have to manage remotely because they’re not remote.
“The virtual desktop infrastructure is going to be one of the pieces of how the new workspace will be able to be delivered,” says Allan Andersen, vice president of product management for virtualization and automation at CA. “Let’s say you’re on a full-featured desktop. Some of the applications may actually be sourced from local, like they’re installed. Some of them may be sourced from a Terminal Server or Citrix ThinApp. Some of them may actually be from the cloud, like SalesForce, which is a Web app. And some of them may actually require launching a VDI to use them, and you may not even know it because it’s only needed just for the application.”
Many Windows 7 users experience client-side virtualization daily when they run a Windows XP application, inside a window that looks more like Windows XP, on their Windows 7 desktops. But VDI is different: The desktop itself is run either primarily or entirely on the server. Certain applications, or the entire desktop itself (depending on the installation), is streamed to the user much like streaming an interactive presentation or a YouTube video.
At issue here is the very foundation of software: the notion that it rests upon a platform delivered by an operating system (OS). A VDI can be established to support consistent, persistent OS images, with applications installed within them. But this is not what virtual desktops have to be, relocated physical desktops reporting in “via satellite” from a remote location. Applications may also be virtualized, with their account profiles and licenses maintained independently. The degree of virtualization may be fractional, and perhaps should be for environments where users can plug in a USB device or connect to their smartphones via Bluetooth, or where they need graphics processing capability for plotting or video that may only be available locally, or when they need to print.
The emergence of VDI raises the possibility that businesses may no longer need to plan their future software migration plans around client operating systems. In a more evolved VDI scenario, if a virtualized application moves to Windows 7, so does its user.
“We have a concept of what we call ‘desktop transformation,’” says Kevin Strohmeyer, senior product manager for one of the two leading “all-in” players in the virtualization space, Citrix. “It does speak to this idea that, for many customers, it might be that the easy first thing to do is just to centralize.” The immediate need Strohmeyer perceives among Citrix’s XenDesktop customers — the reason they make the investment to begin with — is to reverse the course of distribution, so that clients rely on resources that are centralized rather than distributed.
“The state of our industry, certainly for enterprise infrastructure, is that you don’t want to have to be trapped into any particular image,” Strohmeyer continues. “Our vision, which gets exposed through all our products, is that if there’s only one advantage of any instance of an operating system or an application set that you want, it’s to keep it central.”
From there, Citrix believes, customers may choose to start incrementally implementing mix-and-match techniques, some on a granular level that implements different provisioning schemes for individual users. “The next step is what we call ‘optimize,’” he goes on. “You go from centralize first, and then to optimize. That’s where you look at the applications and the operating system that you have out there, and this old image or departmental model that you have, and start to break that apart.”
Making desktops dynamic, Citrix’ Strohmeyer believes, opens up possibilities for businesses to make their operations more dynamic as well, more sensitive to changing conditions, more responsive to potential or actual disasters. “Desktop virtualization is not free at all. It’s much more than optimizing a set of resources in the back end of your data center,” he says.
Multiple Points of Access
Depending on the devices end users adopt for accessing their virtual desktops, some may need some services or programs hosted on the server and streamed live like a remote desktop (RDS), some may need applications delivered to the client and run locally within a hypervisor (the virtualization envelope), and some may need applications hosted on the server and managed by individual server-side hypervisors. Each hypervisor may represent a different operating system version, so a “legacy app” made for Windows XP (and which still doesn’t play well with Windows Vista’s or Windows 7’s security rules) can run alongside a Windows 7 app, with a Web app like Salesforce.com in the middle.
And with Citrix, you can count iPad, iPhone, and Android devices in that mix, thanks to a new client-side app called Citrix Receiver. As CA’s Allan Andersen relates, citing a story told to him by a CA partners, Citrix Receiver on small devices actually led to an opportunity for adding security.
“A very large financial institution wanted to give its people a mobile device like an iPhone,” Andersen reports, “where they could do their e-mail. We all know there’s a very good e-mail client on the iPhone and iPad, but they did not want these people to have the full messages on that device.” For good reasons, the company didn’t want corporate data from e-mails residing on the phones themselves (we’ve all heard stories about iPhones getting lost in bars).
So the company installed an app called Citrix Receiver on each iPhone, and from there users could actually launch a remote, virtual edition of Microsoft Outlook. “This system would then detect that they were accessing the PC from the device, and it would reformat Outlook to fit in that screen resolution, Andersen says. “So it became a lot easier to use Outlook; you wouldn’t pan up and down and figure out how to read the messages, zoom in or zoom out. It was fitted to that screen resolution. . . It’s one of these environments where people are thinking creatively around how they can actually deliver these things.”
Citrix and Hewlett-Packard are strategic partners, which means more than that HP helps new server customers help implement Citrix virtualization. It means that webOS is becoming a factor in the discussion of thin client devices deployed in Citrix XenDesktop enterprises. WebOS is the operating environment for devices that HP acquired in the acquisition of Palm, and is now the environment on new HP-branded smartphones. New HP CEO Leo Apotheker told analysts in March 2011 it would be embedded in every HP-branded PC as soon as next year. HP already has about a quarter of the worldwide thin client device market to itself, according to analyst firm IDC.
Imagine an HP thin client equipped solely with webOS, but which can run a full-screen Windows 7 VDI as if it were local, or Windows apps as though they were locally installed. It’s not too much of a technological step forward from Citrix’ innovation announced last December: embedding a XenApp application virtualization envelope inside a Google Chrome tab, using an HTML 5-based version of Citrix Receiver.
“We have a huge interest in working with partners like HP, Cisco, Google, to basically extend and work within the user environments that they’ve created,” says Citrix’ Kevin Strohmeyer.
The Start of an Open Source Alternative
Although it’s technically not a VDI per se, Ulteo Open Virtual Desktop is perhaps the strongest attempt from the open source community to develop from the ground up a virtual desktop provider that can merge resources from two (and perhaps more) environments. It’s the creation of celebrated Mandriva Linux creator Gaël Duval, and it’s a clear indicator of just how easily modern applications can be “divorced” from the applications to which they’re bound.
Unlike XenDesktop, Ulteo OVD is server-based, which means its entire session is streamed to clients using remote desktop protocols and Microsoft Terminal Server. Demonstrating the gulf that separates its modern policies towards cross-platform innovation that only partly involves Windows, Microsoft has acted as a partner and advisor to Ulteo for OVD.
“The current OVD is not using one XP or Windows 7 instance per user,” Duval tells us. “We are to offer this option at the end of the year (and more), but there are several reasons for sticking with the traditional server-based computing (SBC) approach at the moment: The first is that SBC is “known to work” for many cases in corporate [environments]. The second is that we are focusing on reducing costs, including hardware costs. And SBC has an obvious advantage on VDI in this field.
“That said, what distinguishes the Ulteo approach is twofold,” he continues. “First of all, we offer to mix Linux and Windows applications, transparently from a user perspective. Second, Ulteo software is open source; we want to become the open source alternative in the SBC/VDI field. We are also quite aggressively innovative, but I think most actors tend to be.”
Ulteo doesn’t interfere with how Windows apps are currently licensed and provisioned; that job remains handled by Microsoft Terminal Services, explains Duval. “Both Linux and Windows applications are installed physically on servers so they can potentially be used by a number of users. On Windows of course, the number of users is limited by the number of licenses you have for the software.”
Although it isn’t as sophisticated a system as VMware View or Citrix XenDesktop, Ulteo OVD does offer one of the technical capabilities that Citrix boasts about now.
“Let's take an example: If you are using Ulteo to deliver Microsoft Office, you can offer users access to it from an URL, within a Web browser. That's an option in addition to a standard full-screen desktop. Another option we have developed is desktop integration. Imagine your users are using an XPe desktop, typically on a thin client. Once the Ulteo OVD session is run, shortcuts to published applications will appear on the user's desktop and in the Start Menu, just like if it was running locally on their thin client.”
An example of exactly the capability Duval’s talking about appears in the undoctored figure above. Here, Word 2007 runs in Windows Server 2008 R2, while the OpenOffice.org spreadsheet runs in Linux on the same desktop. The Linux app comes courtesy of application virtualization by way of the Web browser, and Terminal Services enables that Linux app to share the Windows system clipboard. So cut and paste works for the hosted app, as well as printer access.
Duval adds that Ulteo OVD adds the ability to publish applications using separate servers, which enables a scenario where users can appear to be running Internet Explorer 6 and IE9 on the same desktop — something that Windows typically disallows. Although on the surface this may sound like a neat parlor trick, it has a potential practical benefit: Older Web apps that were optimized for use with IE6 (which unfortunately remain many in number) and which therefore cannot be run in Windows 7, can do so under an Ulteo OVD envelope that makes it appear as though IE6 were also installed locally.
The fact that Ulteo can provide at least some of the benefits of a branded virtual desktop at a fraction of its cost, speaks to a growing recognition that considerable virtue is to be discovered by relocating client-side application hosting to the server.
The problem for many businesses, whether they’re experimenting with Ulteo or have already invested in Citrix, VMware, or Microsoft VDI, is that the realization of these virtues is not automatic, and not without some transition pains. Separately, we look at a burgeoning new industry segment in virtual desktop remediation: helping businesses that took the VDI plunge early and lost their way, to get back on track.