Eureka...eureka... Mosquitto works....
Thanks to your contributions I have achieved what I wanted step by step.... for which I thank you.
Indeed Mosquitto has worked in the beginning but I am expecting an opening window.
Meanwhile, I have successfully send a message from the terminal window 1 to 2.
Thanks to all who have taken the trouble to look at my question and send me a possible solution.
See you later.
JackDG
