XenDesktop 4.0 is the latest version of Citrix's desktop and application delivery suite which includes some major changes in delivery and licensing.
The previous version, Citrix XenDesktop 3.0 provided a major leap forward for Citrix in Virtual Desktop Infrastructure (VDI) space, as this version considered by many to be Citrix's first serious contender in the VDI market.
The licensing restrictions in place with the previous versions (excluding the standard edition) have now been lifted in version 4.0 with XenDesktop being able to deliver desktops and applications in a multitude of ways.
The previous versions licensing restricted the delivery of desktops using presentation virtualization when used in conjunction with Citrix XenApp product. If organizations wanted to deliver a XenApp inspired desktop they would have to deploy a separate XenApp solution, which required costlier XenApp licenses. These licensing restrictions only allowed applications hosted on XenApp to be delivered as part of the XenDesktop VDI desktop.
This pushed the cost of deploying XenDesktop higher because only a VDI solution was possible, which in turn required more hardware, as the user density per server was lower than just using a XenApp based solution. It just didn't make sense why Citrix would include the restrictions on XenApp licenses in the XenDesktop suite and stop it's use as a cost effective alternative delivery mechanism for desktops instead of just relying on VDI?
Citrix FlexCast
This inflexibility changed with the XenDesktop 4.0 suite, with the introduction of what Citrix calls 'FlexCast', which is being touted as 'any desktop, any app, any way'. Flexcast can now deliver desktops and applications by a variety of methods including Presentation Virtualization using the terminal server type remote access to applications and desktops along with desktops and applications from VDI hosted machines. There are other methods too, which all in all, give Flexcast a set of totally flexible delivery options.
With Citrix XenApp now being integrated into XenDesktop, the flexibility of catering for a wider variety of users is possible. Those users who don't need full on desktops such as those delivered by VDI, can now access desktops hosted on XenApp, as the XenDesktop license (Enterprise and Platinum Edition only) is free of the previous restrictions.
Citrix Per User/Device licensing
XenDesktop 4.0 also introduces 'per user' and 'per device' licensing options. This brings this Citrix product in line with other major vendors such as Microsoft, who also use the per user/device licensing approach.
Originally, the 'Per Named User' (PNU) licensing model was advocated to replace the current ConCurrent User (CCU) licensing model, however after feedback from customers that this would make this Citrix product very expensive and therefore unattractive, Citrix bowed to the pressure and utilised a flexible licensing approach with a 'per user', 'per device' and CCU licensing (only in certain editions) being available, with PNU licensing being scrapped.
With 'per user' licensing if there were let's say 10,000 users in an organization who all use Citrix delivered applications and desktops and out of these 10,000, only 2,000 access the Citrix delivered applications and/or desktops at the same time, under the existing CCU licensing, only 2,000 licenses would need to be purchased. However, with 'per user' licensing there is a shift for each user who accesses the system being licensed, so in this example, all 10,000 users would need to be licensed. If there were only 2,500 devices being used to access XenDesktop but still 10,000 users, then it would make sense to adopt a 'per device' licensing option.
Citrix is still offering the CCU licensing model but only in the VDI edition, so organisations can pilot the option of going VDI with lower licensing costs.
Education establishments will be able to get campus wide licenses which will make XenDesktop an attractive option.
Using experienced Citrix XenDesktop Consultants may prove worthwhile to ensure not only costs are controlled but the right mix of technology is used.
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