How to organize interaction between frontend and backend for real-time notifications?

To organize interaction between frontend and backend when sending real-time notifications, technologies that support persistent connections or fast event transmission are usually used.

Main approaches:

1. WebSocket — a bidirectional communication channel between the client and server. The backend (for example, in Go) opens a WebSocket server, the client connects and receives notifications instantly.

2. Server-Sent Events (SSE) — a one-way channel from the server to the client, suitable for streaming updates.

3. Long Polling — the client makes a request, the server keeps it open until an event occurs, then responds; less efficient.

4. Using message brokers (e.g., Redis Pub/Sub, NATS) on the backend for scaling and transmitting events between services.

Example with WebSocket in Go (using the gorilla/websocket library):

package main

import (
    "net/http"
    "github.com/gorilla/websocket"
)

var upgrader = websocket.Upgrader{}

func wsHandler(w http.ResponseWriter, r *http.Request) {
    conn, err := upgrader.Upgrade(w, r, nil)
    if err != nil {
        return
    }
    defer conn.Close()

    // Example of sending a notification to the client
    for {
        messageType, message, err := conn.ReadMessage()
        if err != nil {
            break
        }
        // Process message and send notification
        err = conn.WriteMessage(messageType, []byte("Notification: " + string(message)))
        if err != nil {
            break
        }
    }
}

func main() {
    http.HandleFunc("/ws", wsHandler)
    http.ListenAndServe(":8080", nil)
}

On the frontend, connect to ws://server/ws and receive notifications.

Thus, for real-time communication, WebSocket is the best choice, and for scalability, integrating message brokers and distributed systems is recommended.