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

Full-Screen Automation
VET First Stage
The VET command used as a first stage VET command creates the input stream for
subsequent pipe stages by reading data from the virtual screen and passing the
data in the form of messages to the output stream.
If the application running on the VOST presents a full-screen, VET produces a
special message, BNH150I, in the pipe containing information about the VOST
virtual screen. If the application does not present a full-screen, messages generated
by the application are returned.
See “Handling Returned Messages” on page 324 for information about BNH150I
and other messages that can be returned by PIPE VET.
VET, as a first stage, returns the data on the virtual screen in one of two ways:
ROWS
Requests that the screen data be presented to the output stream as 24 lines
of 80 characters each following the BNH150I message header. ROWS
returns the data exactly as it is displayed on the virtual screen.
FIELDS
Requests that each data field on the virtual screen be presented as one line
following the BNH150I message header.
See “Handling Returned Messages” on page 324 for information about the format
of the data returned by VET ROWS and VET FIELDS.
The VET first stage also enables you to specify when you want to read the virtual
screen. The following options are available:
CURRENT
Specifies that the content of the virtual screen at the time VET executes is
to be presented to the output stream. A VET CURRENT after an ATTACH
and before a VET NEXT returns a blank screen of data.
NEXT Specifies that the next change made to the virtual screen is to be presented
to the output stream. In general, the data passed to the output stream is
not a complete screen image. Instead, only the portions of the screen that
have been changed since the last time a first stage VET was executed are
passed to the output stream. If used with ROWS, all unchanged fields are
filled with X'FF'.
VET NEXT must be used to retrieve the first screen of data after an
ATTACH.
VET NEXT is usually followed by CORRWAIT. For more information about
CORRWAIT, see Chapter 2, “Pipeline Stages and Syntax,” on page 19.
A VET Command or Subsequent Stage
After reading data from the virtual screen using the VET first stage, the subsequent
stage form of VET is used to interact with the application running on the VOST by
writing data to the virtual screen and simulating the pressing of the PF, PA, or
Enter keys. To the application running on the VOST, it appears as though a human
operator is entering data on the application full-screen.
Chapter 5. Full-Screen Automation 321