# Pastebin fR4uLeVc
Biny: How ICA virtual channels work
Wfshell.exe loads the user mode virtual channel support on the server side and PicaShell.exe for the workstation VDA. For example, EUEM, Twain, Time Zone, Clipboard, Multimedia, and Seamless Session Sharing.

Others are loaded as kernel mode, for example:

CtxDvcs.sys – Dynamic virtual channel
Icausbb.sys – Generic USB redirection
Icardd.dll (vdtw30.dll legacy) – Graphics redirection driver for Terminal Server based session
Picadm.sys – Client drive mapping
Vd3dk.sys – Direct 3D virtual channel and WDD display driver for workstation based session
Picaser.sys – COM port redirection
Picapar.sys – LPT port redirection
Graphics virtual channel on the server side
Starting with XenApp 7.0 and XenDesktop7.0, ctxgfx.exe hosts the graphics virtual channel for both workstation and terminal server based sessions. Ctxgfx hosts platform specific modules that interact with the corresponding driver (Icardd.dll for RDSH and vd3dk.sys for workstation).

For XenDesktop 3D Pro deployments an OEM graphics driver is installed for the corresponding GPU on the VDA. Ctxgfx loads specialized adaptor modules to interact with the OEM graphics driver.