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

Introduction and Concepts
6 Programming: Pipes
For information on the number of supported streams and the termination
conditions of each stage, see the description of each stage in Chapter 2, “Pipeline
Stages and Syntax.”
First and Subsequent Stages
Another important pipeline concept is that of first and subsequent stages.
A stage that generates an output data stream without requiring an input data
stream is called a first stage. First stages are used to start the process.
Attention: First stages can occur at the beginning of a pipeline specification or
anywhere in a complex pipeline where an input stream is not defined. Examples of
first stages are:
v < (From Disk)
v ENVDATA
v HELDMSG
v QSAM
A stage that accepts input from a stage located before it within a pipeline
specification is called a subsequent stage. Examples of stages that can only be
subsequent stages are:
v CHANGE
v CONSOLE
v LOCATE
v STRIP
Some stages can be used as a first stage or a subsequent stage. Examples of these
are:
v LITERAL
v VAR
Some stages can be used as a first stage or a subsequent stage. However, they have
a different syntax for first stage and subsequent stage forms. Examples of these are:
v NETVIEW
v VET
Figure 8 shows an example of a pipe stage that can be used as a first stage and as
a subsequent stage. In the first stage example, the string HI THERE! is written to the
console. In the subsequent stage example, the NETVIEW stage runs the HELP
command for PIPE LITERAL. The NetView online help information for the PIPE
LITERAL command is displayed on the console after writing the string THE
FOLLOWING IS HOW TO USE THE LITERAL PIPE STAGE.
LITERAL as a First Stage
PIPE LITERAL /HI THERE!/
|CONSOLE
LITERAL as a Subsequent Stage
PIPE NETVIEW (NOPANEL) HELP PIPE LITERAL
|LITERAL /THE FOLLOWING IS HOW TO USE THE LITERAL PIPE STAGE/
|CONSOLE
Figure 8. Examples of First and Subsequent Stages