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Configuring Secure Global Desktop print job conversion

With Secure Global Desktop printing, print jobs are sent from an application server to a Secure Global Desktop server. The Secure Global Desktop server then sends the print job to the client, which sends it to the user's printer. When print jobs arrive at the Secure Global Desktop server, they may need to be converted to a format suitable for the client printer.

To decide whether a print job needs to be converted, the Secure Global Desktop server checks a printer type configuration file to see whether the format used by the client printer matches the format used by the application server. If the format matches, the print job is forwarded to the client device printer without any conversion. If the formats do not match, the Secure Global Desktop server converts the print job to the right format using the tta_print_converter script.

Note A print job from a Windows 2000/2003 application that uses the the Microsoft RDP Windows Protocol is never converted because it is assumed to be correctly formatted.

To ensure that print jobs are formatted correctly, you may have to edit a printer type configuration file and the tta_print_converter script.

Editing a printer type configuration file

Secure Global Desktop uses the following configuration files to determine the printer type:

You should edit these files if you want to support particular printers or add new types of printer.

Note If you add a new printer type, you may also have to edit the tta_print_converter script.

If there is insufficient detail or inaccurate mappings in these files, Secure Global Desktop may convert print jobs unnecessarily or not at all.

Editing the printer configuration file for UNIX Linux and Mac OS X clients

See configuring printing for UNIX, Linux and Mac OS X clients for details of how to configure printers, including setting the printer type.

Editing the printer configuration file for Windows clients

For Windows client devices, the printertypes.txt file maps printer drivers, for example, pscript.dll, to printer types, for example PostScript.

The printertypes.txt file includes comments to help you customize it. By default, the file includes mappings for PostScript, PCL and text-only printers.

Note The printertypes.txt file used for Windows clients also contains entries for UNIX and Apple Macintosh. This is used only as a fallback. For UNIX, it maps UNIX types to printer types. For Apple Macintosh, it maps printer names to printer types.

Note You must be logged on as root to edit this file.

On Microsoft Windows systems, to find out the name of the printer driver used by a client device, print a test page and check the Driver Name field.

To add support for a new printer type, add lines following the same pattern. For example:

Skip past command syntax or program codeMyNewType=mydriver.drv

Example

Rusty Spanner's client device, cairo, runs Windows 2000 and its default printer is PCL. The printer driver in use is unidrv.dll.

The Windows 2000 section in printertypes.txt has the following:

Skip past command syntax or program code[Windows2000]
PostScript=pscript5.dll;pscript.dll
PCL=rasdd.dll
PostScript=*

As there is no specific match for unidrv.dll, the final entry applies: PostScript. This means that when Rusty prints, print jobs are incorrectly converted to PostScript before being sent to cairo.

To fix this, edit printertypes.txt as root to add a specific match for unidrv.dll:

Skip past command syntax or program codePCL=rasdd.dll;unidrv.dll

Now Secure Global Desktop correctly identifies the printer configured on cairo, and print jobs are converted to PCL for that client device.

Editing the tta_print_converter script

The tta_print_converter script converts print jobs from the format used by the application server to the format required by the client device and is determined by the printer type. By default, the script recognizes PostScript and non-PostScript formats. The script uses Ghostscript, available separately, to convert print jobs from PostScript to PCL.

You can edit the tta_print_converter script to recognize and convert between different print job formats or to add support for a new printer type.

The shell function GetDataType determines the print job format from the first 128 bytes of the print job. The data is URL-encoded: for example, the % character is encoded as %25.

The client printer type is passed to this script in upper case, for example POSTSCRIPT or MYNEWTYPE.

The tta_print_converter script can be found in the /opt/tarantella/bin/scripts directory and it includes comments to help you customize it.

If you experience problems printing to a PCL printer, the tta_print_converter script contains some code which has been commented out. You can use this code to see if this solves the problem.

Note You must be logged on as root to edit this script.

Ghostscript

The tta_print_converter script uses Ghostscript to convert print jobs from PostScript to PCL. For best results we recommend you download and install the additional fonts.

When you install Secure Global Desktop, Secure Global Desktop Setup automatically detects Ghostscript if it is installed in one of the following locations:

If Ghostscript is installed elsewhere, you must run the prtinstall.en.sh script with the --gsbindir option to tell Secure Global Desktop where to find Ghostscript.

If Ghostscript is not installed, you must install it and then run the prtinstall.en.sh script.

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