HELP
An object that creates and uses named pipes
for I/O.  To/From Named Pipe is available
only in HP VEE-Test.

USE
Named pipes are tools for advanced
programmers who wish to implement
interprocess communication.

You must add one or more transactions to
To/From Named Pipe to read or write data.  To
do this, click on Add Trans in the object
menu.

LOCATION
I/O ==> To/From Named Pipe

OPEN VIEW PARAMETERS
The open view shows the list of transactions
to be executed.

OBJECT MENU
* Config - Allows you to view and edit the
configuration that determines the end-of-line
character and formatting for arrays.

* Add Trans - Adds a transaction to the end
of the list.

* Insert Trans - Inserts a transaction before
the currently highlighted transaction.

* Delete Trans - Deletes the currently
highlighted transaction.

NOTES
All To/From Named Pipe objects contain the
same default names for read and write pipes.
Be certain that you know which pipe you
really want to read or write.

If the pipes do not exist before To/From
Named Pipe operates, then they are created.
However, there are some overhead costs; if
the pipes exist beforehand, the model runs
quicker.  These pipes are created for you
automatically if they do not already exist:
* /tmp/read_pipe
* /tmp/write_pipe

To create additional pipes, use the HP-UX
command mknod.

Named pipes are opened when the first Read
or Write transaction to that pipe operates
after PreRun.  All named pipes are closed at
PostRun.

Because of the behavior of named pipes, it
is easiest to structure your ToFrom Named
Pipe transactions to transmit known or easily
parsed data blocks.  For example, if you are
transmitting strings, determine the maximum
length block you wish to transmit and pad
shorter strings with blanks.  This avoids the
problems of trying to read more data from a
pipe than is available and of leaving
unwanted data in a pipe.

If you are running discless, be certain
you Read and Write to uniquely named pipes.

SEE ALSO
From, From File, FromStdIn, To File, ToStdIn,
and To.

"Using Transaction I/O" in Using HP VEE,
chapter 9.
