Use Case:

For example, an app like Uber Driver requires the backend to maintain awareness of user-specific connections. Let's assume Uber's search algorithm shortlists 3 nearby drivers; the system needs to send ride requests to these 3 specific drivers. If the backend uses Server-Sent Events (SSE), it must determine which res object corresponds to each user. Similarly, in the case of gRPC, the backend needs to identify which call object is associated with each user.

We can use local map short of thing to store connections but that way is not that scalable So i want something more effective where i can store these connections with a userId reference and can be updated on user connection termination or new connection updates.