For years Citrix has a product to host applications from a centralized locations offering great flexibility and efficiency, called Citrix XenApp. In 2008 Citrix released XenDesktop, the VDI solution from Citrix. With this first release of XenDesktop it was possible to (only) publish a desktop hosted on a single user operating system (like Windows XP, Vista or 7).
Citrix has tried to choose an appropriate name for their products to help customers understand what product offers what solution (and reducing the ridiculous times they rename their products). Although this is an admirable attempt they failed to reach that goal.
A lot of customer assume that with XenApp they can (only) publish applications and with XenDesktop (only) desktops, how wrong can they be?
Customers are confused
Customers confuse functionality, terminology with product branding (and marketing). A functionality like virtual desktops can be offered by both XenApp and XenDesktop, customers assume they need XenDesktop. When an application cannot be hosted on a multi-user platform (or has strict requirements) they know there’s an alternative: hosting the application on a Windows 7 (XP is history) machine via XenDesktop. Again the assumption is made they need to publish a desktop to the user, not just the application hosted on that machine.
The result of mixing up functionality, terminology and products is that customers has requested the wrong solution to their IT department or (worse) implementation partner. In some cases the IT department or implementation partner succeeded in explaining the technologies resulting in proper requirements and a successful implementation. In other cases a “VDI” project is started, some projects actually implemented and in some (rare) cases implemented successfully. I’ve seen customers that has a successfully implemented virtual desktops with Citrix XenDesktop, but ended up hosting 20 different desktops. Each desktop hosted a different set of applications, managing the environment becomes cumbersome.
Get functionality, terminology and products right
Terminology got mixed up because both vendors and community initially did not understand the impact and possibilities of the products that were developed in the years that followed.
When a user connects to a “virtual desktop” he accesses an execution platform that is different than the where is keyboard and screen is connected to. A virtual desktop infrastructure (or VDI) is nothing more than a collection of components that enable the user to connect to this “virtual desktop” with a remoting protocol (like Microsoft RDP, Citrix ICA, etc.).
A virtual desktop can be hosted on a multi-user system (Citrix XenApp) or a single-user system (Citrix XenDesktop or RemotePC). The same applies for applications, applications can be published seamless (!) on a multi-user system (Citrix XenApp) or a single-user system (Citrix XenDesktop) . Most customers (and implementation partners) are not aware of the ability to publish applications seamless from a single-user system with Citrix XenDesktop with VM Hosted applications.
A virtual desktop on a multi-user system (XenApp) is called a hosted shared desktop and a virtual desktop on a single-user system (XenDesktop) is called a hosted virtual desktop.
Flexcast
Although I’m not a fan of marketing terminology like FlexCast I do believe the hit the nail right on the head. With FlexCast Citrix offers a platform to mix and match resources published from different sources seamlessly to the user, meaning user can connect to applications and desktops without knowing where they are hosted.
I strongly believe a user should not be aware of what technology is used, it should application to do its job. For that it needs one desktop to hold its shortcuts to applications, no more. Wetter that desktop is on its physical machine (desktop or laptop) or somewhere in the datacenter that should not matter, but don’t plague them with a bunch of desktops.
To conclude
The difference between XenApp and XenDesktop is not application vs. desktop but multi-user vs. single-user systems.
A “virtual desktop“ can be offered on a multi-user system with XenApp and a single-user system system with XenDesktop.
Do you have a “special” application that needs :
- single-user machine;
- administrative privileges,;
- 3D graphics;
- is selfish with resources (consumes all resource can take) ;
- require a 1-on-1 relation between user and machine (for instance for functional accounts);
- etc.
than publish the application on a desktop operating system (Windows 7, Windows 8) with VM Hosted Apps using XenDesktop, not the desktop 
What’s coming
The customers I speak to are not unique, Citrix has a lot of customers that face the challenges. Fortunately Citrix is aware of this currently developing a new product, currently under the name “Project Excalibur” which is part of “Project Avalon”. This product integrates XenApp, XenDesktop and more existing products in one product. Published resources (applications or desktop) on a single- or multi-user system are no longer bound to a product (XenApp or XenDesktop), it’s configurable for each published resource! Not only will “Project Excalibur” provide a lot of integration between the a lot of products, it could help customer rethink their requirements and do a proper implementation.
The name for this product has yet to be revealed, but it is expected that the name of this product will replace either XenApp of XenDesktop. Although XenApp is well known in the market it is unlikely Citrix will abandon their XenDesktop name, it could very well be that “Project Excalibur” will be the new release of Citrix XenDesktop and XenApp is history.
Hopefully Citrix has read my article about “Citrix and the curse of version 6” and skips version 6 for XenDesktop, which would make sense since XenApp currently is version 6.5.
So next year we’ll have a XenDesktop 7? Only time will tell.
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Nice one Ingmar! We see this issue not only with endcustomers, but also with partners. The marketing of Citrix (and VMware / Microsoft for that matter) is hard to pierce through for (pre)sales. Letting the air out of the marketingballoon leave you with a clear view on what’s behind it … well done!
Hi Rob,
Unfortunately you’re right!
We cannot blaim customers or end-users for not understanding the difference between functionality, terminology and products, the should focus on their core business. “We” as partners, architects, consultant and community should help and advice customers to understand, not all of us succeed.
Cheers
Great Article.
Never considered VM hosted apps before I read this.
Keep up the great work.
I fully agree with Ingmar, also trying to describe a ‘new’ model to customers: non-persistent shared desktop based on XenApp + PvS as an alternative to XenDesktop.
Non-persistent hosted shared desktops are an ideal substitute for “VDI” desktops. It gives the same user experience and reduces complexity (and cost).
I don’t agree that XenApp reduces complexity. It many ways it’s more complex than Windows 7 deployed via XenDesktop (putting the support infrastructure aside).
Many desktop engineers will understand a Windows 7 desktop better than they do an RDS-based desktop. Application installs are easier and support is simpler too.
XenApp costs less in software and hardware, but for many organisations, it might cost less to support virtual desktops than hosted shared desktops.
XenApp reduces complexity by reducing the number of machines that needs to be managed, the architecture of both XA/XD shouldn’t be a problem.
I agree that a desktop OS is easier to understand and offers better support (by the software vendor), but for how many apps is that a problem?
IMO using a “desktop” should be limited to a single instance where applications seamlessly integrate in. If that application has to be on a workstation OS than you should use XenDesktop.
But for a virtual desktop?
A lot of companies already have an existing XenApp environment running and are now considering XenDesktop to have “virtual desktops”, for the wrong reasons.
You forgot yet another FlexCast model that gives the scalability of XenApp with the advantages of XenDesktop: 1:1 Server VDI. In this scenario, you publish a Windows server instance to a single user with XenApp, much the same way you publish a Windows client OS to a user with XenDesktop.
So your conclusion only paints half the picture.
The 1:1 server VDI is a nice workaround if you want to avoid the absense of Windows 7 SPLA license or when XenDesktop is too complex in your situation. But I don’t find it a solution, you’re still on a multi-user platform where not all applications will work. Therefore I don’t consider it a FlexCast model you should consider.
Don’t see how you think 1 to 1 server VDI is scalable.
Also, it is not part of the Citrix Flexcast model.