[WebSocket] How can I send message from server side without receiving message from client

[Gumichocopengin8]

I'm new to Hono!
This example looks like an echo server, but what I wanna do is to send messages from server side as soon as websocket is connected to the client. Is it possible to do so with import { upgradeWebSocket } from 'hono/cloudflare-workers';?
Do I need to do like this instead of using upgradeWebSocket?

I considered using SSE too, but I wanna send binary data instead of text (SSE doesn't support binary data).