#applications

There is a Drupal 7 Web Application which provides personal chats, group chats, real-time polls, theater, and other activities for authorized users.

Hence, the Application contains a lot of callbacks from Front End to Back End.
I think it does not matter: They are callbacks to Drupal (https://www.drupal.org/project/js) and callbacks to node.js (https://www.drupal.org/project/nodejs).

How to test it under loading, simulating the presence of a plurality of users?

Saforian, a web design agency located in Northern Virginia, developed an event app for the upcoming DrupalCon Portland. Our fun, interactive app simplifies the event experience by showing you what’s going on at the conference and the hot spots to check out in Portland, along with making it easy to connect with other Drupal lovers. Not only is the app loaded with useful easy-to-access information but the way it's presented and its user interface are incredibly fun and interactive.