B4J Question how to implement 100 clients send and recieve info from server ?

Do you have control over the clients' code? If you can have them use HTTP, Erel has shown that the jServer library scales quite well even on modest hardware: https://www.b4x.com/android/forum/threads/server-performance-measures.37502/#content . On that same page, in the Similar Threads section, you'll find a bunch of tutorials on how to use jServer.

thanks, i will look at it.

Hi
I use Xampp/RDC , right now there are about 25+ PC / 15+ tablets (not 100) writing and reading to a mysql database every minute, this setup works now for 2years
in production.

https://www.b4x.com/android/forum/threads/cad-cam-app-in-b4j.36148/
1sec for all read and write depends what you do it might create a lot of traffic on the network , we have a program like that and it needs a lot of network traffic