Question:
I experience the following scenarious. What causes this behavior to occur and what changes need to be made to prevent it from happening?

Scenario 1a – On the host an individual file is released for printing, but nothing is printed. The CREO IAPS IPDS server appears to have potentially become hung. If the connection to the CREO IAPS IPDS server is then terminated by the host sending the file, the file begins to print immediately.

Scenario 1b – A series of spool files are placed into a queue on the host and all of the files are printed successfully except the last one, which is not printed. The CREO IAPS IPDS server appears to have potentially become hung when printing this last spool file. If the connection to the CREO IAPS server is then terminated by the host sending the file, this last file begins to print immediately.

Answer:
Typically many high performance spool and RIP printer controllers, sold with many of the modern digital MFP’s and presses, are expected by their designers to receive the majority of the files to be printed from either Microsoft Windows or Apple OS X enabled environments. The current Microsoft printing infrastructure implementation, for supporting TCP/IP attached network printers, is to open and close the TCP socket connection to the target printer for every spool file processed.

In some cases, a high performance spool and RIP printer controller will be designed to not begin the printing portion of spool file processing until the TCP socket connection is closed by the host sending the file because it is assumed by the printer controller that this action signals the job has been successfully delivered from the perspective of the sender.

To date, the IPDS architecture has never implemented a job boundary command. It does include within its command syntax a mechanism to group certain elements together (such as a series of pages needing to be stapled).

These commands are called DGB – Define Group Boundary commands. They can be used to initiate and terminate a group during IPDS spool file processing. In some environments (ex. IBM Midrange servers – Power i/System i/iSeries/AS/400), the IPDS printer driver utilized within the environment has been enhanced to place every spool file processed within DGB commands. This implementation decision develops an “artificial” job boundary, which a device like the CREO IAPS IPDS server can use as a trigger when the need to locate an IPDS job boundary is required.

The CREO IAPS IPDS server has a configuration parameter, which will cause it to close the TCP socket connection to a target printer at the conclusion of every spool file processed when enabled. With this configuration parameter enabled, the specific items that will cause the CREO IAPS IPDS server to close the active TCP connection to a printer are the following:

1. The IPDS connection from the host, which is sending data through the CREO IAPS IPDS Server to the target printer in question, is closed by the host.
2. The CREO IAPS IPDS server encounters an IPDS DGB – Terminate command.
3. The CREO IAPS IPDS Server sees that no information is being received from the host and it is unable to obtain a response to a query packet that it generates. In this scenario, the CREO IAPS IPDS server will terminate the active connection from the host and to the printer after 30 seconds of inactivity.

Point #1 from the above list is controlled by a host configuration parameter with a name like “Release Timer”, “Inactivity Timer”, or “Disconnect Interval”. It is possible to disable this timer or set it to a large value (a number of minutes) so that the TCP connection remains active when printing in high volume operations like print/mail facilities.

The scenario 1a and 1b issues listed at the beginning of this document will occur when the IPDS spool files being processed by the CREO IAPS IPDS server are destined for a printing device, which requires the TCP socket from the IAPS server to close as a signal to begin printing, the incoming IPDS spool files do not include DGB commands creating an “artificial” job boundary, and the host chooses not to close the TCP socket connection.

To resolve the issue, the customer should reduce the timer controlling the opening and closing of the TCP socket to a value between 10 and 15 seconds (varies depending upon the platform and driver being used to generate the IPDS data steam).

The following PSF START PROC example was taken from the IBM Manual “Print Services Facility V4R2 for z/OS (PSF V4R2 for /OS) Customization” and is copyright IBM.

//PRT3 PRINTDEV FONTDD=*.FONT01, /* FONT LIBRARY DD */
// FONT240=*.FONT01, /* 240 PEL FONT LIBRARY DD */
// FONT300=*.FONT02, /* 300 PEL FONT LIBRARY DD */
// OVLYDD=*.OLAY01, /* OVERLAY LIBRARY DD */
// OVLY240=*.OLAY01, /* 240 PEL OVERLAY LIBRARY DD */
// OVLY300=*.OLAY02, /* 300 PEL OVERLAY LIBRARY DD */
// PSEGDD=*.PSEG01, /* SEGMENT LIBRARY DD */
// PSEG240=*.PSEG01, /* 240 PEL SEGMENT LIBRARY DD */
// PSEG300=*.PSEG02, /* 300 PEL SEGMENT LIBRARY DD */
// PDEFDD=*.PDEF01, /* PAGEDEF LIBRARY DD */
// FDEFDD=*.FDEF01, /* FORMDEF LIBRARY DD */
// FONTPATH=*.DOF2, /* DATA OBJECT FONT LIBRARY DD */
// JOBHDR=*.JOBHDR, /* JOB HEADER SEPARATOR OUTPUT */
// JOBTRLR=*.JOBTLR, /* JOB TRAILER SEPARATOR OUTPUT */
// MESSAGE=*.MSGDS, /* MESSAGE DATA SET OUTPUT */
// PAGEDEF=A08682, /* DEVICE PAGEDEF DEFAULT */
// FORMDEF=A10110, /* DEVICE FORMDEF DEFAULT */
// CHARS=60D8, /* DEVICE DEFAULT FONT */
// PIMSG=(YES,16), /* ACCUMULATE DATA SET MESSAGES */
// DATACK=BLOCK, /* BLOCK DATA CHECKS */
// TRACE=YES, /* BUILD INTERNAL TRACE */
// FAILURE=WCONNECT, /* ATTEMPT RECONNECT */
// DISCINTV=0, /* NO TIME OUT */
// MGMTMODE=IMMED, /* MAINTAIN SESSION */
// IPADDR='9.99.12.33' /* IP ADDRESS OF PRINTER */

The value of zero for the time out (DISCINTV=0) means the TCP socket is never closed until the printer connection is terminated. To resolve the scenario 1a and scenario 1b issues, the DISCINTV parameter needs to be changed to a non-zero value. CREO typically suggests trying a value of 10.