stack-blitz working user experience is it socket programming ? . Is that relay advisable for huge application.

stack-blitz working user experience is it socket programming ? . Is that relay advisable for huge application. is it really advisable when we have a azure on premise application where user will be around 70k users at same time. To solve the concurrent user experience

my goal is, if two user working in a dependent item to notify the user immediately any change happened to the data. which the best mechanism i can't have the validation in page load or save.any thing to dig on will be a great help.