Front-end termination
The OPTIONS CLOSE APPLICATION
instruction defines the
callback function in case of front-end termination.
Syntax
OPTIONS ON CLOSE APPLICATION CALL function
- function is the name of a function with no parameters or return value.
Usage
The
OPTIONS ON CLOSE APPLICATION CALL function
can be used to
execute specific code when the front-end sends an application close event. This event can occur in
the following cases:- With the Genero Desktop Client (GDC) in direct mode:
- When the specific application connection in the GDC control panel is closed.
- When the GDC front-end program is closed. This occurs also when the OS user sessions is ended, or when workstation OS is shutdown.
- With the Genero Application Server (GAS) and a web browser, after the timeout defined by the
USER_AGENT
.xcf configuration parameter:- When the browser tab containing application forms is closed.
- When the browser is closed. This occurs also when the OS user sessions is ended, or when workstation OS is shutdown.
- When the Genero Application Server is shutdown.
- With Genero Mobile for Android (GMA), in development direct mode, runOnServer and embedded apps:
- When the front-end or embedded app is closed. This occurs also when mobile device OS is shutdown.
- The event is not send when the front-end or embedded app goes in background mode.
- With Genero Mobile for iOS (GMI), this callback feature is not supported.
Before stopping, the front-end sends an internal event that is trapped by the runtime system. When a callback function is specified with this program option command, the application code that was executing is canceled, and the callback function is executed before the program stops.
Use the OPTIONS ON CLOSE APPLICATION CALL function
instruction with care, and do not execute complex code in the callback function. The code is expected to contain only simple and short cleanup operations; any interactive
instruction is avoided.
Important: A front-end program crash or network failure is not detected and cannot be
handled by the
ON CLOSE APPLICATION
option.Example
MAIN
OPTIONS ON CLOSE APPLICATION CALL end_app
MENU "test"
COMMAND "quit" EXIT MENU
END MENU
END MAIN
FUNCTION end_app()
DISPLAY "Program terminated by front-end..."
END FUNCTION