On 27/06/2022 7:09 am, Andrew Rowley wrote:
On 24/06/2022 3:17 pm, David Crayford wrote:
There's a more complete example here
https://github.com/zsystems/java-samples/blob/master/MvsConsoleInteraction.java.
Using Object.wait()/notify() is a bit hairy. A more modern
implementation would use Condition.await()/signal() but it's fine for
this use case.
I cut as much as possible out of my example so there was less code to
wade through to see the logic of the stop/modify etc.
There are some significant differences between the IBM example and mine:
- The IBM example does nothing until it receives the MODIFY command.
My example does something (sleep), and responds to STOP and MODIFY
commands.
In a real implementation the sleep would be replaced with the actual
function of the STC. I think this is more realistic, most STCs have a
function they perform until they are stopped - they don't just respond
to modify commands.
That's ok for a simple single threaded server but won't fly if you use a
framework. We use the Spring Boot application framework which implements
multiple concurrent services. We spin up a ConsoleController thread that
shuts down the Spring application context on a STOP command for a clean
termination.
Our stuff can run on distributed systems so using a console listener is
optional. Unless you REALLY need to run on z/OS (native code) you should
strive to write Java applications that can run multi-platform.
- The IBM example returns true from handleStop which results in an
immediate System.exit(0). I think this will result in an ugly abend if
there is a dataset being processed at the time because it is not
properly closed. My example is designed for a clean shutdown.
It's a simple sample. But it shows a useful model which is how we used
it in more sophisticated environment.
Object.wait/notify is probably a reasonable approximation of an ECB. I
would be more inclined to use higher level constructs.
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