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

Introduction and Concepts
Stage Input and Output
4 Programming: Pipes
Note: In portrait form you must include the appropriate continuation character for
the programming language after each line except the last.
For readability, most examples in this book are shown in portrait form.
PIPE STAGE1
| STAGE2
| STAGE3
| STAGE4
| STAGE5
| STAGE6
Figure 4. A PIPE Command Coded in Portrait Format
PIPE STAGE1 | STAGE2 | STAGE3 | STAGE4 | STAGE5 | STAGE6
Figure 5. A PIPE Command Coded in Landscape Format
For more information, see Chapter 2, “Pipeline Stages and Syntax,” on page 19.
An important concept in the processing of pipelines is the passing of data, or
messages, from one stage to another by data streams or streams. A data stream is
a logical link between one stage and another that provides for the transfer of
messages.
The messages entering a stage are passed on its input stream. The messages
leaving a stage are passed on its output stream. In the example in Figure 3 on page
3, LOCATE reads all messages from its input stream, but writes only the messages
containing the string BOB to its output stream.
Figure 6 shows how messages flow through several stages. The output of the
LOCATE stage becomes the input to the TAKE stage.
Bob Smith
Fred Ford
Mary Bobbit
Locate /Bob/
Stage
Fred
Ford
Bit
Bucket
Bob Smith
Mary Bobbit
Figure 6. Messages Flowing through Multiple Stages
Take 1
Stage
Bit
Bucket
Bob Smith
The LOCATE stage reads three messages from its input stream: BOB SMITH, FRED
FORD, and MARY BOBBIT. It writes the messages containing BOB to its output stream.
The TAKE stage reads messages from its input stream. There are only two
messages: BOB SMITH and MARY BOBBIT. TAKE selects the first message and writes a
single message to its output stream.
A stage can have up to ten input and output streams, numbered from 1 to 10. The
first two streams are called the primary stream and the secondary stream. Some
Mary
Bobbit