Citrix XenDesktop Flexcast removes the restrictions in XenDesktop version 3.0 on how applications and desktops can be delivered. Including allowing full XenApp functionality which previously only allowed hosted applications to be delivered as part of the XenDesktop 'Virtual Desktop', that is the virtual machine which the user had access to. Meaning these hosted applications could not be delivered to the user outside of this virtual machine, that is directly to their local desktop.
To be able to use XenApp functionality outside of these restrictions, that is have the hosted application available direct to the user's local desktop, required the purchase of separate XenApp licenses, which in turn added substantially to the deployment cost.
This inflexibility changed with version 4.0, with the introduction of what Citrix calls 'FlexCast', which is being touted as 'any desktop, any application, any way'.
FlexCast removes the restrictions on how applications and desktops can be delivered. So whilst previously XenApp applications could only be delivered as part of the XenDesktop Virtual Desktop, now they can be delivered directly to the user's local desktop without any need to purchase separate XenApp licenses on top of the XenDesktop licenses.
Hosted desktops can also be delivered by XenApp to the user's local desktop, this was previously restricted, giving the a multitude of ways of delivering applications and desktops.
It's important to note that there are still restrictions but these are based on the edition of the XenDesktop product used. The VDI edition doesn't allow the XenApp functionality and is only designed for small scale deployments, which will allow organisations to assess the merits of VDI.
Citrix XenApp's full inclusion into the XenDesktop suite, gives the flexibility of catering for a wider variety of users. Those users who don't need full on virtual desktops such as those delivered by VDI, can now access desktops hosted on XenApp, with the XenDesktop license (Enterprise and Platinum Edition only) being free of the previous restrictions.