Network Printing in Windows for Workgroups (90275)

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Printing from an MS-DOS-Based Application

When an MS-DOS-based application writes data to a printer port connected to a network printer, the network redirector intercepts the data and sends it across the network to the appropriate server. For most server types, including Windows for Workgroups and Microsoft LAN Manager, the server writes the data into a spool file on disk as the data is received.

Because MS-DOS-based applications do not generally close the port they print to, the redirector on the client machine decides when the job is finished based on the amount of time the application has allowed to elapse without printing. In Windows for Workgroups 3.1, if the application does not print any data for the number of seconds specified by the PRINTBUFTIME= entry in the [Network] section of SYSTEM.INI (45 seconds by default), then the redirector assumes the print job is done. (Note that in Windows for Workgroups 3.11, the PRINTBUFTIME= entry is in both the [network] section and the [ifsmgr] section of SYSTEM.INI file on the client machine). Care is taken so that the time in which the printing application is in a suspended state within Windows for Workgroups is not counted against the timeout value.



When the print job is done, the network redirector tells the server to begin closing it. At this point, the server can close the spool file and begin sending its contents directly to the printer hardware.

Printing from a Windows-Based Application

When a Windows for Workgroups client prints from a Windows-based application, Windows (GDI.EXE) passes the application data to the appropriate printer driver, which converts it into a data stream that is fully formatted and ready to send to the printer hardware. If Windows determines that the target printer is a network printer, then it passes this data to the network driver. The network driver calls the redirector to send the data to the server, and close the print job when completed.

Note that in both of these cases, the data sent across the network has been fully formatted for the target printer, and the client computer must have a printer driver correctly configured for the printing device attached to the server computer. Once the print job has arrived at the server, it is sent to the physical printer without modification.

Separator Pages Handled Differently

There is an exception to the above information. If a print server is configured to print a separator page and a job is received from the network, the server's printer driver is used for the formatting of the separator page's data. All other formatting is done in advance at the client machine.