Server to app communication

can p5.js be used for programming an interactive website with a server communicating to a processing app: Around 100 clients should be able to enter the page and set data. Then the server computes an output and a message with some numeric data is sent to a local processing app. I could not find a tutorial adressing the server side programming and sending data from the server.

I have no particular expreience with p5.js but I have to figure this out for writing a concept until end of this week. So a feedback of people having done this kind of stuff already would be appreciated.

ok I see my question seems to be answered by this tutorial: