This is a coding example working on Caché 2018.1.3 and IRIS 2020.2 It will not be kept in sync with new versions It is also NOT serviced by InterSystems Support !
Since the very beginning of Caché and most of its predecessors
there exists a way of in-memory communication of processes.
It's called InterJob Communication - IJC.
I have the feeling it's forgotten by most developers now.
here is the documentation: Communication Between Caché Processes
Earlier I've written about command pipes.
This is the internal variant of a PIPE.
To make this more tangible and visible for you I prepared a small example
The scenario is to run a monitoring process that receives
input from an unknown number of sensors.
(Could be Lab equipment or similar.)
The monitor should not poll his sensors nor run
in a hang loop to scan a common ^global
and work independently of any disk access.
To try it log into a terminal
DO ##class(IJC.Demo).%Start()
The Highlander principle applies for this example: There can only be one
Next open a new terminal and run
DO ##class(IJC.Demo).Sensor("mytext")
and see what happens.
It's clear that for real applications:
- the monitor might run in a background tasks
- the sensors will do something useful.
But this reduces visibility.