Lately, I have been noticing an ongoing trend when speaking to new customers about VDI: they forget about good old Citrix XenApp. Typically, they begin the conversation by talking about their VDI initiative, when what they really want is application access for users, both internal and external. I follow up by asking if they are currently using Citrix XenApp. Often, the answer is, “What is XenApp?”. I then explain to them that XenApp has been Citrix’s legacy product since the company was founded (granted, the name has changed a handful of times).
Citrix XenApp is installed on top of Windows 2008 R2 RDS (Remote Desktop Services). XenApp provides the same robust ICA/HDX protocol and policy control that XenDesktop provides. The big difference between XenApp and XenDesktop is that multiple users connect to a single XenApp server, while a single user connects to a XenDesktop virtual desktop.
On the flipside, you receive economies of scale. If you have 25 users connecting to a XenDesktop solution, that equals 25 virtual desktops with a minimum of 2 GB per desktop, along with one vCPU. For that same user count, I could have one XenApp server configured with 12 GB of memory and four vCPUs. Of course, the application requirements could change that example.
One of the big roadblocks with a XenApp solution is application compatibility. To this day, many applications are not compatible or supported on Windows 2008 R2. That is when we start to look at a mix of XenApp and XenDesktop, or, depending on size, a strictly XenDesktop solution. As with any user application solution, you need to properly classify the users and the applications they require.
In summary, the next time you are thinking of a strictly VDI solution, ask yourself, “What about XenApp?”