VMware OEMs a sub-set of the .Print Server Engine full-blown product. Many people think ThinPrint is a VMware owned product and/or feature, but it is not. ThinPrint is a German company that stands on its own and was founded in 1999. Their .print generic drivers can be found in a range of strategic partnerships with VMware, Citrix, Fuji Xerox, HP, Lexmark, Microsoft, Wyse, and others. ThinPrint has managed to embed their ThinPrint agent into a range of devices, from Thin Clients to Printers and the company reign almost alone in its market segment.

The ThinPrint OEM version in VMware View allow soft-clients (View Client) to present printers to the virtual desktop. Printing is possible from a virtual desktop to printers that are defined on the client device. The printer drivers and devices MUST be configured and connected to client device. The printers can be local or network connected (direct IP or print server).

The ThinPrint port monitor is the heart of the .print Engine. It acts as transport layer for the Windows print spooler. Main features are:

• Multi protocol (virtual channels like PCoIP,RDP, TCP, LPD)
• Integrated to Windows print system – port pooling, cluster ability
• Control of bandwidth for print data
• Print data are transferred compressed

When a user connects to the virtual desktop the TPAutoConnect service starts a process to communicate with the .print Client and the end-point.The client-device must support .print technology. This end-point can be the VMware View Windows or a ThinClient with the .print client. If the end-device in use does not support .print technology only network printers are enumerated.

The printer creation process is done in 3 steps:

1. get the printer list
2. get the printers properties
3. create the session printers with transferred properties

Steps (1) and (2) are performed by the tpautoconnect.exe (user) process and (3) by the TPAutoConnect service.

The tpautoconnect.exe process on the virtual desktop queries the .print client for state changes every 30s. Only the status change flag is transferred, not the whole printer list. If there were changes to the local printer setup (newly created printer, a printer was removed from the list etc.) the AutoConnect complete communication process is executed once again.

If you want to learn more about printing in VDI read my previous articles: Printing Architectures for VDI (Part 1) and (Part 2).

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Use the troubleshooting process below if virtual desktop desktops running ThinPrint are printing correctly to the virtual printer device, but there is no print out.

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This article was first published by Andre Leibovici (@andreleibovici) atmyvirtualcloud.net.