Problem

By default, InterPlot requires that offline raster files be written on the plot server's local hard drive. This can be inconvenient for some custom workflows or for centralized management of a group of plot servers. With the steps listed below, you can modify the system to support UNC filenames (filenames of the form \\servername\sharename...).

 

Solution

The primary obstacle to using UNC directory names and filenames with InterPlot is Windows security. When a plot job arrives on the plot server and enters the printer queue, the InterPlot print processor uses Windows impersonation to acquire the user rights of the submitting user. In theory, this means that a given plot job should be able to write to any UNC share that the submitting user is able to write to. However, for reasons Microsoft was unable to provide, the impersonation is incomplete, and the job runs in a credential-less mode--with no user name or password assigned to networking operations. When no user name and password are present in a file share connection request, this is termed a "null session."

By default, the Windows file sharing software prohibits null session users from accessing file shares. However, on Windows
it is possible to modify a registry key to allow null session access on a per-share basis.


Enabling Null Session Support

Suppose you have a plot server named PLOTSRV and a file server named BIGSRV. On BIGSRV, there is a share called "plotfiles" in which you want to store offline files generated by InterPlot on PLOTSRV. You have enabled "full control" for all users and all users can write files to \\BIGSRV\plotfiles. Now you must enable "Null Session Support" for the share as described in Microsoft knowledge base article Q121853. Perform these steps on BIGSRV.

1. On BIGSRV, start Registry Editor and locate the following Registry subkey in the HKEY_LOCAL_MACHINE subtree:

\SYSTEM\CurrentControlSet\Services\LanmanServer\Parameters

2. Select the NullSessionShares value.

3. From the Edit menu, choose Multi String.

NOTE: values will already exist and should not be replaced.  If the values are accidentally deleted, just choose Cancel
and try again.

4. Select the first blank line after the values that currently  exist. (The lines above should not be highlighted.) Add the name
of the share you want to accept null sessions. (For example, if  the UNC path is \\bigserv\plotfiles, then you you put the share
name "plotfiles" (without the quotes) in the NullSessionShares  value.)

5. Choose OK and exit Registry Editor.

6. This step is mandatory. You must either shut down and restart Windows NT or from a command prompt type: NET STOP SERVER.  Then type: NET START SERVER.



Offline Driver with UNC Names

The InterPlot Offline Raster Driver includes the InterPlot Batch Port monitor. The Batch Port monitor automatically writes offline raster files according to a user-specified configuration. You can select the output directory and the file naming convention based on series number, job names, user name, etc.

Unfortunately, the port configuration dialog box uses a directory browser to select the output directory. This means that you cannot manually key-in a UNC directory. To set the UNC directory, you must use the registry editor. Use these steps on the plot server:

1. These steps assume that you already have the Offline Raster driver  configured and are using it to create offline raster files in a directory local to the plot server. If this is not true, create a queue and configure an Intergraph Batch Port as desired.

2. On the plot server, start Registry Editor and locate the following Registry subkey in the HKEY_LOCAL_MACHINE subtree:

/SYSTEM/CurrentControlSet/Control/Print/Monitors/ Intergraph Batch Port/Ports

3. Select the name of the port you wish to change.

4. In the right half of the registry editor, double click on the "Directory" field.

5. You should now be presented with the "String Editor" dialog box. Enter the UNC name of the directory you want offline files
written to. To use the previous example, you could enter \\BIGSRV\plotfiles

6. Select OK.

7. The next plot sent to this offline queue will be written to the UNC directory you entered.