While Remote Desktop Services provides a complete desktop with the Start menu,
sometimes end users don’t want a complete desktop. Instead, they want a specific
application displayed on their device, such as a line-of-business application or an
office application. This is especially true when using a smaller device such as a phone
or tablet. Imagine trying to interact with the complete Windows desktop on a 4-inch
iPhone screen compared to just launching a specific Windows application. Or say that
a user is already running a Windows desktop but has to run a specific application
remotely. In these cases, the users just want the application’s window to be displayed
on their existing desktop or device, without a completely separate desktop, in order to
launch applications from a website or some kind of local application catalog. Windows
Server 2008 introduced the ability to publish applications in addition to a full desktop,
which allowed just the application window to be sent to the user’s local device.
For a long time, this type of session virtualization was the most popular way to
provide a virtualized desktop. Recently, Virtual Desktop Infrastructure (VDI) has been
getting a lot of attention and is being touted as the best solution by many vendors. A
VDI solution differs from session virtualization in that each end user connects to a
separate client operating system running in a virtual machine, as shown in Figure 11.2.
This gives a greater level of isolation for each user, since the users are now running in
their own isolated operating system; therefore, it is a good fit for power users and
developers who need to customize the operating system or reboot it. The downside is
that a VDI solution uses up far more resources, because each VDI desktop is a
complete desktop environment including memory, processor, and desk utilization.