UDP is a network protocol at OSI level 4, similar to TCP
It is not as popular as TCP but especially focused on Speed
https://en.wikipedia.org/wiki/User_Datagram_Protocol
This example runs 2 containers talking to each other over UDP.

Clone/git pull the repo into any local directory

git clone https://github.com/r-cemper/UDP.git

To build and start the container run:

docker compose up -d && docker compose logs -f

To open IRIS Terminal session do:
for the first IRIS container

docker-compose exec iris iris session iris
USER>

for the second IRIS container

docker-compose exec iris2 iris session iris
USER>

To access the first IRIS System Management Portal
http://localhost:52773/csp/sys/UtilHome.csp

To access the second IRIS System Management Portal
http://localhost:42773/csp/sys/UtilHome.csp

The functionality is the same in both containers and has to be done
individually for both.They just differ in their Names iris and iris2
and in the related IP addresses. Both use port 5200 for communications.

USER>do ##class(UDP.demo).ini()

Now both instances refer to each other

USER>write ##class(UDP.demo).get()

now the4 first container is listening and the second sends a hello to it

do ##class(UDP.demo).send()

For some more text than just Hi, I have prepared a
LOREM IPSUM sequence with $c(3) aka ETX as terminator.
One container starts listening

USER>do ##class(UDP.demo).log()

while the other container is sending its LOREM IPSUM

USER>do ##class(UDP.demo).lorem()