IBM Tivoli NetView for z/OS Programming: Pipes - IBM notice

Emptying the Pipeline: HOLE
NCCF NETVIEW CNM01 OPER6 03/26/10 09:02:44
* CNM01 DROP2
’ CNM01
IST350I DISPLAY TYPE = MAJOR NODES
IST089I VTAMSEG TYPE = APPL SEGMENT , ACTIV
IST089I A01MPU TYPE = PU T4/5 MAJ NODE , ACTIV
IST089I ISTPDILU TYPE = CDRSC SEGMENT , ACTIV
IST089I ISTCDRDY TYPE = CDRSC SEGMENT , ACTIV
IST089I A01APPLS TYPE = APPL SEGMENT , ACTIV
IST089I A01MVS TYPE = APPL SEGMENT , ACTIV
IST089I A01USER TYPE = APPL SEGMENT , ACTIV
IST089I A01CDRM TYPE = CDRM SEGMENT , ACTIV
IST089I A01CDRSC TYPE = CDRSC SEGMENT , ACTIV
IST089I A01LOCAL TYPE = LCL 3270 MAJ NODE, ACTIV
IST314I END
C CNM01 RETURN CODE IS 0
Processing steps:
1. The NETVIEW stage runs the MAJNODES command list. Usually, this displays
active major nodes in a domain on your console. When the command list is
issued within a pipe, the output messages are placed in the pipeline.
2. The CORRWAIT stage allows a 10-second wait for messages to be returned
from VTAM.
3. Before the 10 seconds expire, the message DISPLAY NET MAJNODES returns to the
pipeline and is passed to the next stage. The DROP stage reads its input stream
and discards the message.
4. Again, before the 10 seconds expire, the second message DISPLAY ACCEPTED
returns to the pipeline, is read, and discarded by the DROP stage.
5. Again, before the 10 seconds expire, the MLWTO is passed to DROP, and
because DROP has reached its maximum discard count, the MLWTO is
preserved in the pipeline.
6. The CONSOLE stage reads the messages and displays them.
This section describes how to discard all messages from the pipeline, thus
emptying it of all contents.
Determining Correlation: HOLE
Discarded messages from the pipeline Using the HOLE stage, you can, for
instance, empty the pipeline of messages after writing them to a variable or to test
a command for correlated output.
Example: Determining Command Response Correlation to a Command
This example shows how to use the HOLE stage to determine whether a command
and its messages are correlated. If the messages are correlated, they enter the
pipeline and are discarded; otherwise, they are displayed.
PIPE NETVIEW MVS $D I | CORRWAIT 25 | HOLE
Output (first page only) from the command looks similar to:
NetView Pipeline Filters
Note: These messages represent uncorrelated messages, indicating that the
command is NOT supported for pipeline processing. They displayed
immediately after the PIPE command was entered.
Chapter 4. NetView Pipeline Filters 313