A nice extension to this: run iris and with an ipm package on-board. Here is one command to start IRIS and install  web-terminal:

docker run --rm --name iris-ce -d -p 9091:1972 -p 9092:52773 -e IRIS_PASSWORD=demo -e IRIS_USERNAME=demo intersystemsdc/iris-community -a "echo 'zpm \"install webterminal\"' | iriscli"

Hi Hugh!

In my case even the messages are csv lines they are being resulted in one csv file.

It is the matter of what file is pointed out in the outbound adapter, as @Jeffrey Drumm 
mentioned. Take a look the code or try to run this production - it is in docker, so it is really easy to reproduce it on your laptop and see how it works.