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Sure Provision provides an integrated desktop feature with their app-portal desktop integration product. That's an option as well.

Unity is like Coherence. Similar in concept but different in implementation. Unity windows are individually separated where Coherence windows are grouped. As an example Unity windows will all separate when using Expose where Coherence windows with stay grouped together. Another example is bringing an application window to the front. Unity windows will individually come the front, where all Coherence windows come forward when one is selected.

While the RemoteApps feature is available under Longhorn TS, it is not available under Vista. Both WinXP and Vista ignore a startup app if you were to specify one. Going further, if you were to take a .rdp file generated under Longhorn TS and manually edit it to point it to a Vista machine, you simply won't get anything when you launch it. I actually was curious enough to try myself and it just didn't work. Has your experience been any different?

The only company that has overcome this limitation is Provision Networks (www.provisionnetworks.com). Earlier on, they were having some stability issues with their hook due to the session switching process that takes place under the hood when logging on remotely. During our pilot phase, we had to hard-reset some VMs from time to time due to this issue. I believe they just worked out all the wrinkles in their latest in-VM agent (pntools). I also got to see their RemoteApps imlementation for Vista. Pretty impressive.

ML.

Hi Warren,

A customer sent me a link to this thread.

To answer your question, session switching takes place invariably under the hood during the logon process, and this has nothing to do with sharing a Windows XP machine among multiple users and violating the EULA. VDI is all about 1 user = 1 computer, and that's one of VDI's strengths. We're not trying to convert Windows XP or Vista into a multi-user OS.

As for why session switching occurs during logon, the matter is too involved to discuss here, but you'll just have to attach a debugger to winlogon to see what really takes place under the hood. As far as our implementation goes, a nasty race condition was taking place inside our winlogon hook due to session switching, but we finally were able to identify the issue and resolve it. Having said that, we just put the final touches on a new framework for app publishing that's compatible with XP, Vista and Longhorn - We plan to release it later on this year.

As for the value of app publishing in a VDI environment, it's the same value proposition that app publishing vs. desktop publishing brings to the table in a Terminal Server environment. And that's the premise on which the Provision Networks solution is based. Company employees may be using thin clients at the office, and therefore would receive a full desktop experience from a hosted machine. On the other hand, home-based, after-hours, and mobile users would much prefer the published app approach because, more likely than not, they're accessing their remote desktops from a Windows PC or laptop. To deliver a remote desktop that obscures the local desktop, and having to switch back and forth between the remote and local desktops, is by no means intuitive. Besides, customers who are committing to implementing VDI just don't want to maintain a parallel TS system for remote access purposes. Instead, they want to use the VDI platform as a remote access solution, not just a desktop management solution. In effect, Virtualization platform + VM-based desktops = A Terminal Server-like model.

One of the reasons why many IT organizations are favoring VDI over TS is because VDI mainly revolves around hosting a "standard" Windows desktop OS. Therefore, no special TS know-how is required. And it's not just about TS know-how, but also about the myriad apps out there that just won't work out of the box on TS without drastic steps to mitigate multi-user conflicts. There are many use-cases that I've documented over the years.

The desktop/app delivery model that we deliver today in our solution (i.e., logically grouping VMs and managing them as terminal server silos), and the myriad enhancements that we'll be delivering by end of year and Q1 2008, has been on our drawing board since late 2003. Interestingly, the first person to whom I've shown this model outside of Provision Networks was a former VMware employee who previously worked at Citrix for years, and then went on to work for Softricity prior to the Microsoft acquisition.

Peter Ghostine
CTO, Provision Networks