Subject: TN5250E printing and WCO object name

From: [email-masked]
Date: Tue, 21 Apr 1998 17:29:42 -0700

Ref: 10. Telnet Printer Startup Response Record

     Can RFC 1572 and the server be changed to detect and report an invalid
     WCO library name?

     One of the printer options is for a Workstation Customizing Object
     name (IBMWSCSTNAME and IBMWSCSTLIB).  But if a PC sends invalid data
     in the library field, the connection fails with no error message
     reported.

     For example, if IBWSCSTLIB is *NONE (which is illegal but only after
     you think about it) then the client fails to connect (which seems
     reasonable) but there is no error response record sent to the PC to
     tell anyone why it failed.  The WCO is a free-format text field, so
     there's no reasonable way the PC client program can report all
     possible errors at the time of configuration.

     I might suggest possible values returned could be 8916 "no matching
     device found", or 8928 "change of device failed". Or better yet a new
     value could be added for WCO problems.

     By the way, if IBMWSCSTLIB is *YIPPEE or a non-existent library name
     then the printer connects, but if it's set to *NONE then it fails.  I
     believe it would be better to reject all invalid values than to
     silently create a LUD different than what was configured.

     Thanks for your help,
     Barry Hansen
     [email-masked]

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From: Jeffrey Stevens <[email-masked]>
Date: Wed, 13 May 1998 16:17:32 -0400

Barry,

Telnet has error flags in the passthrough header, but whether you get an error
for this condition is not clear (value checking for WSC objects is in the
printer passthru code, and we are not familiar with the details on error
handling).   I think if an error is being reported, you need to refer to
draft-ietf-tn5250e-02.txt section 11 on how to read them.  Startup errors like
yours are inside the printer datastream, and are not known to the Telnet server
itself (Telnet does no inspection or analysis of the printer datastreams that
it carries); it is the job of the Telnet client (printer emulator) to read
errors.

If a picture will help, think of Telnet data as the IP packet, and the printer
datastream as the TCP packet.  TCP packets are encapsulated inside IP packets.
Telnet (IP packet) just serves up the printer data (TCP packet) to the next
layer, which is printer passthru.  What you are requesting would need to occur
over in the printer passthru layer, so Telnet server can do nothing here.

Jeffrey Stevens/Endicott/IBM - AS/400 TCP/IP (Telnet/WSG/LPD)
Work:  [email-masked]   Personal: [email-masked]
"Diplomacy - the art of letting someone have your way."

[email-masked] on 04/21/98 08:44:39 PM
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Subject: TN5250E printing and WCO object name

     Thanks for your help,
     Barry Hansen
     [email-masked]