How to Implement a Multiplayer Matchmaking Server Without Persistent Sockets?

Question

I am building a multiplayer matchmaking game server using Express.js where:

• Clients join a queue and wait for enough players.
• The server periodically checks the queue and tries to create a match.
• Once a match is made, the server notifies the clients with a match ID.
• The server should not maintain a persistent WebSocket connection with clients.

Possible Approaches I Considered:

1. WebSockets: Clients connect to the server, and the server keeps them connected until matchmaking completes. (Not scalable for large numbers of clients.)
2. Client Polling: Clients repeatedly ask the server if they have been matched. (May cause unnecessary server load.)
3. Background Matchmaking Process:
   • Clients send a request to join the queue.
   • A background worker runs periodically and matches players.
   • Once a match is found, the server notifies clients (either via polling or webhooks).
   • Clients then connect to a game server instance to start the game.

I want to implement approach #3 where:

• The matchmaking logic runs in the background.
• The server only sends a match ID to the client when a match is found.
• No persistent connection is required between server and client during matchmaking.

My Questions:

1. What tools or libraries should I use to handle matchmaking efficiently?
2. How can I notify clients when a match is found without using WebSockets?
3. Is Redis + BullMQ a good choice for queue management?

Any guidance or better approaches would be appreciated. Thanks!