I want to monitor in real time the data that users enter in comments
table.
I have an Apache server running, and suppose that has a node server on port 1337.
You have basically the choice between Websockets and long polling.
Decide which technology you want to use and start implementing your use case. Consider that Websockets are more or less new. Depending on your requirements you might not be able to use Websockets because you might have to support crappy browsers. See this page.