A XenApp is a virtual application that you can manage
using a XenApp server. To secure the virtual applications, you must
install Traps on the XenApp server that handles the sessions. Instead
of using the VDI license on the XenApp server, you must install
a single Traps server (most common) or a workstation license based
on the operating system of the XenApp server. In this instance,
the single Traps installation protects all concurrent sessions.