Hono
Are Server Sent Events possible with Hono? #1355
Replies: 4 comments 1 reply
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You can't do it directly. But, you can utilize Streams API, which might allow you to achieve something similar. Refer to the following documentation: https://developer.mozilla.org/en-US/docs/Web/API/Streams_API |
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example of sse import { Hono } from 'hono';
import { html } from 'hono/html';
/// sse sample application
export const sse = new Hono();
// sse sample
sse.get('/api/events', async (c) => {
let eventCount = 0;
// create a stream that emits events every 500ms to
// simulate some real-time data source
const stream = new ReadableStream({
start(controller) {
controller.enqueue('data: stream started\n\n');
},
async pull(controller) {
controller.enqueue(`id: ${eventCount}\n`);
controller.enqueue(`data: event #${eventCount}\n\n`);
eventCount++;
return new Promise((r) => setTimeout(r, 500));
},
cancel() {
console.log('stream cancelled');
},
});
return c.body(stream, {
headers: {
'Content-Type': 'text/event-stream',
'Cache-Control': 'no-cache',
Connection: 'keep-alive',
},
});
});
sse.get('/sse', async (c) => {
const pageHtml = html`
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8" />
<title>server-sent events - hono</title>
</head>
<body>
<h1>Server-sent events</h1>
<button onclick="source.close()">Stop event stream</button>
<ul id="events"></ul>
<script>
const events = document.getElementById('events');
const source = new EventSource('/api/events');
source.onmessage = (event) => {
events.innerHTML += '<li>' + event.data + '</li>';
};
</script>
</body>
</html>
`;
return c.html(pageHtml);
}); |
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How could I apply this using the queryStream from the oraclenode lib? const readableStream = new ReadableStream({
start(controller) {
controller.enqueue('data: stream started\n\n');
},
async pull(controller) {
streamOracle.on("data", async (row) => {
controller.enqueue(`${JSON.stringify(row)}\n`);
})
eventCount++;
},
cancel() {
console.log('stream cancelled');
},
})This code does this in the console MaxListenersExceededWarning: Possible EventEmitter memory leak detected. 11 data listeners added to [QueryStream]. Use emitter.setMaxListeners() to increase limit
(Use `node --trace-warnings ...` to show where the warning was created) |
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Here's how we're using SSE with Hono for dev server live refresh in Hwy. Works great! https://github.com/hwy-js/hwy/blob/main/packages/dev/src/refresh-middleware.ts |
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It will be introduced in this PR: #1504 Will merged and new version including this will be released later. |
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I can't get SSE to work with Hono. Usually in Express of Fastify you'd be able to do
res.write()which doesn't kill the connection. Is that possible?Beta Was this translation helpful? Give feedback.
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