Traditionally, XenDesktop will require a XenServer back- end, the XenDesktop which acts as the desktop delivery con- troller or the desktop image provisioning engine and the XenApp delivery server to provide remote desktop connectiv- ity to the desktop images through the ICA protocol (see Figure 6). However, because XenDesktop was formed from the Ardence acquisition and Ardence supported VMware ESX Server first, it also supports a full VMware backend. In addi- tion, because of its strong partnership with Microsoft, XenDesktop has been adapted to support a Windows Server 2008 Hyper-V backend. This means that you can use the XenDesktop solution with any of the major server virtualiza- tion engines (see Figure 7).
This is a boon for most every organization because early adopters of server virtualization will often already have both Citrix Presentation Server (now named XenApp but used for Presentation Virtualization only) and technologies like VMware ESX Server or Microsoft Virtual Server (which they will no doubt upgrade to Hyper-V) already in place. Since they already have a server virtualization infrastructure and they already own Citrix products, adding XenDesktop is often a very low-cost solution for the introduction of virtual desktop infrastructures.