How to organize internal notifications (bell on the website)? What transport to use?

To organize internal notifications with a bell on the website, WebSocket is often used — it is a bidirectional communication channel between the client and the server, allowing the server to send notifications in real-time without the need for constant polling.

Main steps:

1. On the server (for example, in Go), implement a WebSocket server that maintains open connections with clients.
2. On the client (in the browser), open a WebSocket connection and listen for events.
3. When a new notification appears, the server sends a message via WebSocket to the specific user.

If WebSocket is not suitable (for example, due to infrastructural limitations), Server-Sent Events (SSE) can be used for one-way notifications or periodic polling with AJAX.

Example in Go using Gorilla WebSocket:

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()

    for {
        // Wait for a message from the client or send notifications
        _, _, err := conn.ReadMessage()
        if err != nil {
            break
        }
        // Here you can send notifications
        err = conn.WriteMessage(websocket.TextMessage, []byte("New notification!"))
        if err != nil {
            break
        }
    }
}

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

Thus, WebSocket is an optimal transport for internal notifications with a bell on the website.