Citrix claims app compatibility issues in today’s world are a myth. Is this true?

Application compatibility (or “app compat”) is one of the most important issues when architecting, designing, or implementing a desktop or application virtualization solution.

Application compatibility (or “app compat”) is one of the most important issues when architecting, designing, or implementing a desktop or application virtualization solution. After all, if you have an application that’s not compatible with your delivery solution, well, then you pretty much have no choice but to not use that solution!

In the earliest days of Terminal Server and Citrix MetaFrame, everyone knew there were some apps that just wouldn’t work on MetaFrame. Some had issues where they wouldn’t work on the multi-user Terminal Server platform, and others had graphical or peripheral problems that prevented them from running in a remote host-based computing environment.

A few years later, application virtualization and streaming technologies were introduced that “fixed” a lot of the problems that apps had in Terminal Server environments. Unfortunately, not all apps were compatible with the streaming solutions either, so you ended up with a patchwork of apps that would only work with one delivery method but not another. (And of course you still had some apps that wouldn’t work with any non-traditional delivery mechanism.)

Over time, we all just grew to accept that not all apps could be brought into our alternative environments, and that our “old way” of doing things would probably have to be around forever to support some crazy legacy application.

Of course the holy grail of app virtualization is the mythical “100% compatibility.” We’re all fantasizing about a future where all apps can be virtualized and where nothing needs to be done the “old” way. But how close are we to such a world?

Citrix’s “myth” campaign

If you ask Citrix, they’ll tell you that we’re pretty close. In fact Citrix has recently launched a massive multi-pronged viral campaign debunking application compatibility “myths.” In other words, they’re saying, “it’s a myth that so many apps are not compatible with XenApp.”

One piece of this campaign is a 5-part YouTube video where each video debunks a certain “myth” about XenApp application compatibility. For example, in Part 1, Citrix’s Bill Hartwick talks about the Citrix Ready community-verified app website where people discuss and “certify” apps to run on XenApp. He also touches on AppDNA’s APPtitude, a tool that analyzes your applications to see what delivery platforms they’ll work on. (Tim Mangan reviewed APPtitude a few months ago on>)


Parts 2-5 of this video series discuss multimedia, offline, local devices, and user experience challenges.

Citrix also launched an application compatibility website at as a central starting point for those interested in figuring out whether their apps are support in XenApp.

There are also some, um, “non-standard” videos out there. This one show a couple of guys in the woods, debunking myths about app compat:


Today’s app compatibility reality: community edition

Based on what you know about XenApp and what you’ve seen from Citrix, do you think app compatibility is still an issue today? Do we still have to design XenApp farms to augment the “old” way of doing things because we don’t yet have 100.00% compatibility? (Does 100.00% compatibility even matter, or is this just something where I’m the only one making a big deal about it?) Could it be true that problems with app compatibility are truly relics of the past that don’t affect us in today’s world?

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In my experience the only apps that I can't get to run on XA are a tiny percentage of apps that are:

1) So old that the original in-house developer or vendor is gone. In all of these cases an upgrade is warranted anyway so I don't worry. I.e. I don't give a crap abut 16 bit apps anymore, I just force people to upgrade stupid apps, but get in dinosaur organizations this may still be an issue.

2) Licensed vendor apps that will not allow installation on a server OS. I hate these companies, but this is where VDI does help, and I think MS should not allow these companies to tout that they are Windows certified apps!!!!!

3) Rich Multimedia apps, although things are getting better, but still not there. I.e. Desktop Video.

4) Not all apps can be virtualized, drivers, service (although not in all cases). But I usually get around that with smarter packaging, like put the driver in the build or a separate MSI and virtualize the bits that change..

So to answer your question, I don't think 100% compatibility matters, but there are some areas that need focus to enable broader adoption of VDI and SBC to deliver apps and desktops. I certainly do not think paranoia over a few apps negates the benefits of moving to a SBC/VDI etc. I also think once Windows 7 is out with R2 on the server side, it will further improve things since the kernel versions of the MS desktops and server OS will be the same. That said I expect there will always be the one important app for every person that just is always better run local for a myriad of reasons. This is where I think the SBC/VDI combined with client side and app virtualization as one system represent choices to address many use cases.


It has been a few years since I have run into any applications that were cludgy in a multi user environment.  I do agree that it does not really matter when it comes to 100% compatibility.  However, most shops (at least that I have seen) have engineers that are still not comfortable with ALL of the different methods available in order for them to get all of their apps working successfully in a SBC/VDI/Streaming type environments.  There is a lot of uncertainty around anything new (and to many Admins, this is new technology that they have setup in labs) I think it is driven by the fact that everyone is comfortable with the old way of doing things and feel like they want the "disruptive technology boom" to shake out before they actually commit to implementing some of these features/solutions in their "production" environments....Sorry for all the quotes, just feeling quotey!


I HATE THAT TERM!!!!  "Applilcation Compatibility" is a term that ends up confusing people.  Problem applications include the problems of "Application Conflict", "Multi-user awareness", "Multi-Tennancy", and OS Compatibility.  The solutions to each of these challenges are sometimes different or non-existent.

So for example, virtualizing an application will not solve an OS Compatibility issue.

Vendors generally have been improving, but there are still a lot of application issues that need help in a multi-user scenario.


One things that everyone keeps forgetting, just because you can hack the program to install and run in a multi-user environment doesn't mean its supported by the vendor.



The situation with apps is much better then ever before, there are many tools and built in features which help with multi-user and OS compatibility issues.

However, at no fault of Citrix or Microsoft, there are still some apps that simply don't work, are very complicated to make work, or, as Joe Shonk pointed out, not supported by the ISV in Terminal Services.

This percentage is much lower now and for the vast majority of projects and customers it is a non issue. However, dealing with complex environments we still often hit one or two of these on a project and these challenges do arise.

I would say for 99% of environments, Citrix's "Myth" message is pretty accurate. For the exception cases and special requirements we have VDI....


We at Ericom have encountered situations in which customers used applications that were not compatible with Windows servers. A solution we provide in such situations is to publish such applications seamlessly from virtual desktops running Windows XP.


Good question and comments. Thanks for pointing out the Community Verified site at

I would encourage everyone to add their knowledge and experience with the apps they deploy on XenApp. This helps everyone when considering how to deliver apps. Shout out to VisionApp and Rene Vester for being the biggest contributors.


Why would you need to virtualise the OS if we had 100% app compat?

XenApp everything.... All apps, any device, any network (remeber thosemarketing slides?)!!!

Does XenDesktop only exist because 100% is the myth?