H
HonoKillian Di Vincenzo

StreamSSE on http2

Hi ! It seems that the streamSSE feature is not correctly adapted to work on http2. It adds the following header ‘transfer-encoding’->‘chuncked’, which is not authorised on http2. 
var streamSSE = (c, cb, onError) => {
  const { readable, writable } = new TransformStream();
  const stream = new SSEStreamingApi(writable, readable);
  c.header("Transfer-Encoding", "chunked");
  c.header("Content-Type", "text/event-stream");
  c.header("Cache-Control", "no-cache");
  c.header("Connection", "keep-alive");
  run(stream, cb, onError);
  return c.newResponse(stream.responseReadable);
};
var streamSSE = (c, cb, onError) => {
  const { readable, writable } = new TransformStream();
  const stream = new SSEStreamingApi(writable, readable);
  c.header("Transfer-Encoding", "chunked");
  c.header("Content-Type", "text/event-stream");
  c.header("Cache-Control", "no-cache");
  c.header("Connection", "keep-alive");
  run(stream, cb, onError);
  return c.newResponse(stream.responseReadable);
};
so it gives me an error : 
(node:4570) UnsupportedWarning: The provided connection header is not valid, the value will be dropped from the header and will never be in use.
node:internal/http2/util:531
      throw new ERR_HTTP2_INVALID_CONNECTION_HEADERS(key);
            ^

TypeError [ERR_HTTP2_INVALID_CONNECTION_HEADERS]: HTTP/1 Connection specific headers are forbidden: "transfer-encoding"
    at mapToHeaders (node:internal/http2/util:531:13)
    at ServerHttp2Stream.respond (node:internal/http2/core:2786:25)
    at [begin-send] (node:internal/http2/compat:836:19)
    at Http2ServerResponse.writeHead (node:internal/http2/compat:711:21)
    at responseViaResponseObject (file:///home/**/node_modules/@hono/node-server/dist/index.mjs:341:14)
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5) {
  code: 'ERR_HTTP2_INVALID_CONNECTION_HEADERS'
}
(node:4570) UnsupportedWarning: The provided connection header is not valid, the value will be dropped from the header and will never be in use.
node:internal/http2/util:531
      throw new ERR_HTTP2_INVALID_CONNECTION_HEADERS(key);
            ^

TypeError [ERR_HTTP2_INVALID_CONNECTION_HEADERS]: HTTP/1 Connection specific headers are forbidden: "transfer-encoding"
    at mapToHeaders (node:internal/http2/util:531:13)
    at ServerHttp2Stream.respond (node:internal/http2/core:2786:25)
    at [begin-send] (node:internal/http2/compat:836:19)
    at Http2ServerResponse.writeHead (node:internal/http2/compat:711:21)
    at responseViaResponseObject (file:///home/**/node_modules/@hono/node-server/dist/index.mjs:341:14)
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5) {
  code: 'ERR_HTTP2_INVALID_CONNECTION_HEADERS'
}
I can't use the SSE and I desperately need it to continue developing my application. It's such a trifle ... I'm an opensource neophyte, should I create an issue on github? And until it's adapted to http2, is there an interesting workaround, without having to go back to h1?
Nico
Nico•19d ago
What runtime are you using? In Bun http2 is not supported yet. I would have to do research to see if that would effect how this works in node as well or another runtime if you are using those
Killian Di Vincenzo
Killian Di Vincenzo•17d ago
Hi @Nico ! Sorry for responding late. I was using bun before using http2, but now I'm using nodeJS. I found a workaround for a little time by doing : 
const streams = await streamSSE(c, ...)
c.res.headers.delete("Transfer-Encoding");
streams.headers.delete("Transfer-Encoding");
return streams
const streams = await streamSSE(c, ...)
c.res.headers.delete("Transfer-Encoding");
streams.headers.delete("Transfer-Encoding");
return streams
And then, the server stop crash and clients managed to connect to the server ; but the stream disconnected immediately with the same error (but no more crash) : UnsupportedWarning: The provided connection header is not valid, the value will be dropped from the header and will never be in use.
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