On 19 Oct 2005 09:34:23 -0700, in bit.listserv.ibm-main
(Message-ID:<[EMAIL PROTECTED]>)
[EMAIL PROTECTED] (Walt Farrell) wrote:
Suppose the modal application were ATTACHEd (or spawn()ed) and
control were returned to the TMP without doint a WAIT (or
waitpid),
but leaving a communication channel open between the
application
and the TMP; perhaps ECB semaphores, POSIX pipes, or sockets.
(I suspect the implementation of the modal EDIT is
somewhat like
this.) Further line input from the TMP, CLIST, or EXEC would
be passed to the modal application, which would return messages
and status. This interaction would continue until the
TMP passed
the application an END command and the application returned a
status indicating it exited.
The modal app does not return to the TMP. The app simply
issues a PUTGET to prompt and obtain a subcommand. If the
app is running in a CLIST the "get" part of the PUTGET is
satisfied when the CLIST eventually reaches something that
is not a CLIST statement, but a command, and the app gets
that returned to it.
Is the CLIST "TERMIN" command considered modal? The
CLIST continues to run (sort-of) but no code in it is
executed until the user enters one of the operand
commands. Any other TSO commands can be issued, including
modal ones.
Since the command prompt looks the same (READY), this
has possible security implications (as a trojan, for instance).
(Note: Don't try this under ISPF; it must be done in
native TSO.)
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