How should I manage the number of sockets in a node.js application?

Question

I am building my first web-based node.js application - an online game - as a hobby/project to try and teach myself how it all works.

I'm using socket.io to send real-time updates (who's in the lobby, points scored etc) to users, but I'm not sure whether the way I'm managing the sockets, and the information being sent through them, in the best way.

Whenever the game is updated, I'm sending an object to each user which updates everything at once, and a lot of the time, the information being updated is actually staying the same. For example, if a user scores a point, an update is sent to everyone's browser to update the leaderboard, but that same socket.on function is re-sending information such as usernames, which stay the same throughout the game:

exampleObject = {
  "usernames" : [username1, username2], // only gets updated in the browser once, but is sent every time
  "points": { 
    "username1": 1, // Different value with every update
    "username2": 3
  }
}

(The real object is quite a bit bigger than this)

Would it be more sensible to have a different socket.on function for every individual piece of information which needs updating, so I can then call them individually as and when required, or is there any sense in updating everything through one function? Any thoughts/advice would be greatly appreciated.

Answer 1

If you are regularly sending a piece of information over and over, then it makes sense to design a specific message that only contains that specific information so you aren't regularly sending information that does not need to be sent. You can have as many different messages as you want and you should use that to design efficient messages, particularly for the most common messages.

Would it be more sensible to have a different socket.on function for every individual piece of information which needs updating, so I can then call them individually as and when required

Yes. Design efficient messages specifically for things you regularly send.

or is there any sense in updating everything through one function?

Only if you need to change lots of stuff at once. It's wasteful to include data in a frequent message that never changes and doesn't need to be sent.

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It's perfectly fine to have different messages you send for different purposes and then the client has different listeners for those specific messages. At the same time, if you regularly send three pieces of data together, you probably wouldn't make a separate message for each piece of data - you'd put those three together such that your message structure aligns with your usage.

And, you can also have different messages for different purposes even if some data is in both messages.

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One more note here. The title of your question "How should I manage the number of sockets in a node.js application?" seems to ask about managing the number of sockets. But, the rest of your question isn't about that at all. The rest of your question is about having different messages on the same socket. You don't need a new socket in order to define and use a different message. You can have thousands of different messages that you use all on the same socket connection. That's the whole architecture of socket.io. You send a message name and some data that goes with it. You can use a limitless number of separate message names all on the same connection.