Figure 9 illustrates the steps involved in Manual Printer Queue creation.
Figure 9 Manual printer queues
Most of the steps in this process are identical to the process for configuration changes. However, there are a few subtleties to note.
As part of its initialization, WLNOTIFY.DLL registers to the Spooler service to get notification for any new printer queues that might be manually added within the session.
1. When an administrator manually adds a printer and associates the printer with a valid client-side port (client-side PRN ports are invalid), the above registered notification gets triggered. The notification includes the printer name.
2. WLNOTIFY.DLL looks at the notification and checks its internal list of printer queues to see whether the printer queue really belongs to it. If WLNOTIFY.DLL cannot find the printer name, it checks whether this is a new manual printer attached to one of its internal device list of ports.
3–4. If it finds the port in its internal list, it creates a temporary file and passes this file name to a call into PRINTUI.DLL to get the printer queue configuration details.
5–6. PRINTUI.DLL calls into Spooler to fetch the configuration information and then saves it in the temporary file that WLNOTIFY.DLL supplied.
7. WLNOTIFY.DLL reads the configuration information to obtain the driver name and other relevant information from the temporary file.
8-9. An Add Printer message is created. This message contains the printer name, driver name, and any other relevant information. This message is then sent to the client by using an IOCTL to the KERNEL-mode RDPDR.SYS.
10. The Terminal Server Client RDPDR.SYS component receives the Add Printer message and looks up the printer name to which the message applies. The client does not try to interpret it, but simply stores it in the registry under the following registry key:
HKEY_CURRENT_USER\Software\Microsoft\Terminal Server Client\Default\AddIns\RDPDR.SYS\<printer queue name> \PrinterCacheData
During the next server connection, when announcing the printers, the client reads this information from the registry and includes this printer queue to be redirected.
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