In my previous article about Windows XP, I promised to do a piece on XenDesktop 7 (XD7), well… here it is. I already described some of its sub features during one or two of my previous articles where we had a look at VDI in general, pooled vs. dedicated (or persistent) virtual machines and more specific, VDI-in-a-Box. Throughout this article, I’d like give you a high level overview on XenDesktop 7, describing some of its main features including a word on the editions available and the accompanying license models that go with it. Be sure to check out the ‘A final word’ section as well before commenting with regards to the newly introduced XenApp and XenDesktop 7.5 editions. XenDesktop 7.x is still a long way from being dead and buried, as you will find out shortly.

Let’s start at the beginning

Most of you probably associate Citrix with their (MetaFrame) Presentation Server or XenApp products. If you are looking for an enterprise-ready application and/or desktop hosting platform then XenApp is (or was) most likely to come out on top. It’s flexible; you can publish applications, Host Shared Desktops, or a combination of both, out to your users. Applications can either be installed and managed centrally using a physical or virtual XenApp server or they can be virtualized by leveraging Microsoft’s App-V or Citrix’s own application profiling solution, which, as of XenDesktop 7 is no longer supported, it’s just App-V from now on.

XenApp gets installed on top of a Microsoft Server Operating System on which Terminal Services or RDS needs to be enabled / installed as well, adding in the multi user functionality. Simply put, it works like this, when installing an application on a XenApp server, it gets prepared and configured for multi user support, meaning that a single application can be accessed and used by dozens of users at the same time. Again, this is where the Terminal Services or RDS functionality comes in. The total number of concurrent users per application, or on the XenApp server itself for that matter, depends on the type (or different types) of applications that get published and the configuration and physical resources of the underlying XenApp host itself.

Another option is to configure a Hosted Shared Desktop and publish it out to your users. This is a very popular approach and is often combined with published and/or virtualized applications complementing a base set of applications installed on the Server OS itself, like Adobe, Office, IE plugins or whatever it is you may need. We’re talking about a single, full blown, desktop accessible by multiple users at the same time, and a hundred percent manageable by IT. If you prefer then your users will have the look and feel of a normal desktop OS and will only be able to perform those actions that you’ll allow them to. No access to the C:\ drive for example, no application or update installs, you can redirect their Documents and Desktop folder, implement and configure some sort of user profile solution, and the list goes on. It’s very cost effective since multiple users will share the same centrally managed desktop, and when configured properly, your users won’t notice a thing when it comes to individual computing power. Of course there will always be exceptions and it won’t fit all use cases, but it will get you a long way, that’s for sure.

XenApp is up to version 6.5 and that’s where it ends as well (at least that’s what we thought just a few months ago). Citrix decided not to continue their XenApp (IMA) line of products; instead, its functionality (XenApp) is now part of Citrix’s XenDesktop 7 release. Because of this, although most of its functionality hasn’t changed, its underlying infrastructure has, dramatically I might add. This, especially if you are a die hard XenApp administrator, also means you’ll need to change your approach and way of thinking when designing new architectures. Never mind that the whole management interface, and way of doing things has also changed, again, this only applies if XenApp is all you know. For existing XenDesktop administrators however, things only got better, newly added powerful technology, in the form of XenApp, on top of an already robust and enterprise-ready product, including multiple enhancements to XenDesktop itself as well.

New editions are on their way

Most of you probably know, or heard, that Citrix announced the return of XenApp together with a new version of XenDesktop, 7.5 to be exact. It will be another month or so before these two will be officially released. But just to take away your confusion, not much is going to change. Both XenApp and XenDesktop will still be built on the FMA architecture, so the statement ‘no more IMA’ still applies. Both products will also be managed using the exact same management toolset and consoles as with XenDesktop 7. To go short, with XenDesktop 7 both products were merged into the same architecture (FMA) with XenApp and XenDesktop 7.5 the architecture (FMA instead of IMA as far as XenApp is concerned) will stay the same, the only difference is that both products will be sold separately again. I’ll dedicate one of my future articles to XenApp and XenDesktop 7.5.


Now that we’ve established the functionality XenApp has to offer and that, from now on, it will be part of the XenDesktop product line (or at least it will be, and stay, part of the FMA architecture) let’s see what XenDesktop is all about. XenDesktop isn’t new; it has been around for a couple of years and hasn’t gone unnoticed. In some ways, it can offer the same functionality as XenApp, it’s just not multi user orientated. XenDesktop has originally been developed with client operating systems in mind, virtual desktop infrastructures (VDI) to be exact. Multiple VM’s based on client OS’s, all provisioned, management and monitored centrally from one or two consoles. So instead of configuring and publishing a server based desktop (the Hosted Shared Desktop model mentioned earlier) for multi user use, you create, configure and publish out single VM instances to users on a one on one basis.

The same goes for applications as well, you can publish an application from XenDesktop in sort of the same way as with XenApp, only with XenDesktop it will run on a single user, client OS based VM, and as such it will only be accessible by one user at a time. Great for offering users their own (personal) desktop on an individual basis, but, in most cases, a different use-case when compared to XenApp. As far as application publishing goes; if an application for whatever reason specifically needs a client OS to run on, then you might consider deploying it this way, for anything else you go with XenApp instead. Although chances are, you probably won’t have both (XenApp and XenDesktop) infrastructures in place.

A word from Citrix, this applies to both XenDesktop in general and XenDesktop 7 as well: The biggest difference between the two (XenApp and XenDesktop) is the ICA protocol stack used. For desktop machines, Citrix ships a single-user ICA stack (internally known as PortICA) which allows only one ICA session at a time. This version connects users to the machine’s console session, similar GoToMyPC or other Remote Access products for a Desktop OS. It also includes additional HDX features such as USB and Aero redirection, which are only available on a single-user machine. For server machines, Citrix includes a multi-user ICA stack, which extends Windows Remote Desktop Services with the HDX protocol. This is the same ICA protocol stack developed for Citrix XenApp, just with a different management interface to make it compatible with XenDesktop 7 controllers. But what happens if both products meet under the same roof?! Exactly, magic happens!

XenDesktop 7

With XenDesktop 7, we have it all, client and server operating system functionality all under the same roof. No more separate infrastructures for desktops and applications, it is one install, architecture and console (Citrix Studio) to meet all our delivery needs. Although I mentioned that both products will be separated again, the above still applies, they both will continue to use the exact same (FMA) architecture and as such can be mixed and matched just as easy.

We can publish Hosted Shared Desktops and applications for multi user use; configure complete virtual desktop infrastructures (VDI) and applications on an individual basis and all this using multiple provisioning and delivery methods. As mentioned, XenApp is now part of the FMA infrastructure and that’s probably one of the biggest changes involved. FMA includes several workflows, which simplify and speed up the process of delivering desktops and applications to our users. Delivery Agents (get installed on all machines as part of the FMA and are used for communication purposes) in XD7 are configured via policies. Any combination of Active Directory GPOs, the Studio console (HDX Policy), and Local GPO settings can be used.

Not only do we need to get used to new management consoles (as opposed to the Delivery Services Management Console used in XenApp 6.5 for example) terminology and a new way of configuring desktops and applications, XenApp is also based on the Independent Management Architecture (IMA), which is a big change from FMA. I’m not going into too much detail regarding the differences between the two, just know that if you’re used to thinking in IMA terms and concepts you’ll probably need a day or two (probably more) to get your head around FMA. If you’re already familiar with XenDesktop, then adopting the new XenApp functionality will take you 15 minutes tops, as far as configuring and deployment goes anyway, although It might take some more time to fully understand the concept behind the technology.


This one is easy, have a look at the matrix below, it pretty much speaks for itself. Do note that because of the newly introduced XenApp and XenDesktop 7.5 editions, App Edition will eventually disappear and some other features might be corrected as well. Make sure to check this one out as well, it’s a complete overview on all security, monitor and management features available per edition, it’s a big list. It also shows all features and capabilities of both the XenApp 6.5 Enterprise and Platinum edition.

XenDesktop 7 is available in VDI, App, Enterprise and Platinum edition of which only the App Edition is (or was) new. You can choose to buy per-user, per-device or concurrent licenses. User licensing gives users access to their virtual desktops and apps from an unlimited number of devices. Device licensing gives an unlimited number of users access to their virtual desktops and apps from a single device. Concurrent licenses are tied to a session, not to a specific user or device. It works like this, as per Citrix: When a user launches a session, a license is checked out to that session. When a user logs off from a session, the license server checks the license back in the pool, making it available for another user.

App Edition

App Edition has recently been added to the XenDesktop portfolio. XD7 App Edition, which is basically a replacement for XenApp, lets you publish Hosted Shared Desktops as well as Applications and it also supports App-V delivery for off-line applications. If you own XenApp 6.5 Enterprise or Platinum licenses and have a valid Subscription Advantage then it’s offered free of charge. It can be installed alongside your existing XenApp environment (production). This way you can make use of the newly added XenDesktop 7 HDX functionality and also provision Windows Server 2012 Hosted Shared Desktops next to your existing XenApp 6.5 Farm (which doesn’t support 2012). Simply configure Web Interface or StoreFront (a central portal used to present you with your applications and or desktops) accordingly and you’ll have access to both environments from one interface. From there, you can always upgrade to one of the other XD7 editions whenever you want, giving you full access to the HDX feature set and the FlexCast delivery suite (a suite of delivery methods used to deliver an application or desktop to your users, out of scope for now). However, XenApp 6.5 Advanced license owners are out of luck, they simply need to pay. Note that, as I already highlighted, the XenDesktop App Edition will eventually be replaced by one of the new XenApp 7.5 editions, probably the Enterprise edition.

Monitoring and analysis

Depending on the edition you purchase, you’ll get additional analysis and monitoring functionality. First is the Citrix Director, which is a real time web based tool used primarily by Helpdesk and/or Call center Agents, is included with every edition. It offers you real time assessment and troubleshooting capabilities, like live health monitoring of your XenDesktop 7 Site. It also includes a new troubleshooting dashboard allowing you to see on a per-minute scale if any failures have occurred. It also includes Filtered views, Trends views and a Help Desk view.

Citrix Director includes something called; EdgeSight technology. EdgeSight used to be a separate product offering advanced monitoring and load testing capabilities. As of XenDesktop 7, it’s now offered as an integrated service which can be ‘activated’ with the proper licenses in place. You will need a XenDesktop 7 Platinum license to make use of the EdgeSight functionality. It will offer advanced performance management together with network analysis capabilities. As far as performance management goes, this will give you up to a full year of monitoring data to collect and store. It needs a SQL database for this. Besides that, if you want to make use of the network analysis feature and you have a NetScaler (you must have this in place, otherwise it won’t be available) set up, you will also need a NetScaler Enterprise or Platinum license. Depending on your NetScaler license you can respectively store either 60 minutes or unlimited network data from your NetScaler appliance, to sum it up:

  • * All editions: Director – real-time monitoring and basic troubleshooting (7 days of data)
  • * XD7 Platinum: EdgeSight performance management feature – includes historical monitoring (up to a full year of data through the monitoring SQL database)
  • * XD7 Platinum + NetScaler Enterprise: EdgeSight performance management and network analysis – includes 60 minutes of network data
  • * XD7 Platinum + NetScaler Platinum: EdgeSight performance management and network analysis – includes unlimited network data

A final word

Now that we’re finally used to XenDesktop 7, sort of anyway, they already announced the return of XenApp. XenApp and XenDesktop 7.5 will both be released in March of 2014. Don’t worry, not much has changed, all of the above still applies. Both XenApp and XenDesktop are still based and built on the underlying FMA architecture and, from a technical point of view, the only thing that has been added is the Hybrid Cloud Provisioning feature, a subject I will discuss in one of my upcoming articles. They’ll also throw in a free copy of XenMobile MDM if you purchase XA or XD Platinum licenses and a 20% discount on the XenMobile Enterprise edition as well.

Next to that, Platinum license owners can also make use of the full App-DNA feature set as an additional bonus. Again, in one of my future articles, I’ll discuss both XA and XD 7.5 in more detail. For now just now, most (the biggest part anyway) of the above will also apply to both xenApp and XenDesktop 7.5, including the Director and EdgeSight functionality. It also means if XenApp 6.5, or an earlier version, is all you know, a lot has changed, IMA is very different from FMA. So even though XenApp and XenDesktop are going to be separate products, again, this doesn’t change the way both products function and the features they deliver. If you get the above, you’re fine!