SSH Reference Manual

RESILIENT YES | NO
RESILIENT is an option for TYPE DYNAMIC services that allows the application to remain active after the terminal
session is disconnected. The STN implementation of RESILIENT is similar in general functionality to that of HP
Telserv, but with some key differences.
RESILIENT NO, the default setting, defines a traditional dynamic service. Upon session disconnect, file system errors
are returned to the application, and most applications, like TACL, will detect this and stop. If KILL_DYNAMIC is set,
STN will stop the application on session disconnect.
When RESILIENT is set to YES, LOGON is automatically set to REQ.
A typical use for RESILIENT is to define several TACL windows which run at high priority. By logging on to these
TACLs once and disconnecting, they are primed and ready for quick reconnects. This avoids the overhead of process
creation and logging on, which can be critical when a system administrator needs immediate access.
When a session requests a RESILIENT service, STN first checks for any existing windows left over from previous
sessions for the service. If any such window is found, the session is connected to that window. The application that was
running on that window during the previous session will, in general, repeat its prompt, but otherwise the session resumes
exactly where it left off. For example, a TACL will still be logged on and have its environment intact. Specific operation
during such a reconnection is described below:
1. STN first notifies the workstation user that the session is being reconnected to a resilient window with the
message:
STN70 Reconnecting to resilient window #ZWNnnnn
Last access: <time>
2. Then STN displays information about any application programs running on the window, example:
STN70 application $Y1G7 $SYSTEM.SYS00.TACL
STN70 application 1,175 $SYSTEM.SYS00.FUP
The application line is repeated for each opener of the window, including process name, cpu/pin, or posix
pid, and the object file name. This helps clarify exactly what is running in the resumed session.
3. Finally the session is then resumed with handling dependent on the application I/O that was active when the
previous session was disconnected.
• ITI (conversational), read or writeread pending
The application I/O is completed with febreak 111. For TACL and most other applications this repeats the
prompt.
For OSS (posix) reads, fesigint 4523 is returned. For /bin/sh and most other applications, this repeats the
prompt.
• ITI (conversational), no read or writeread pending
This happens when TACL is PAUSE-d, etc.
Guardian break or OSS SIGINT is generated, again generally resulting in a new prompt.
• Block Mode 6530
Terminal is placed into block mode. Error 191 is returned to the application. This forces most block mode
applications to refresh the display.
EDIT XVS will allow for session recovery. TEDIT refreshes the screen. Most Pathway applications refresh
the screen.
If there are no existing windows, STN will create a new window and start a new application process, like any TYPE
DYNAMIC service. The following message is displayed to clarify that a new session was created as opposed to a
reconnect to a previous session:
STN70 No existing window available for resilient service,
256 • STN Reference HP NonStop SSH Reference Manual