callback in on(eventType: "data", callback) of ClientReadableStream won't be not called

[Gumichocopengin8]

Hello,

I use Tonic and Tonic-web without Envoy proxy (Tonic-web takes over Envoy) for server and use gRPC-web in client with React19 + Vite.
When I call server steaming like the following code, I see the streaming running without errors in the browser network tab, but don't see console logs at all. When I test a unary RPC, it works. Is it a gRPC-web issue or something wrong in the server code?

useEffect(() => {
   const  client = new TestServiceClient('http://localhost:8888');
 
   client.unary(new Arg(), null).then((res) => { // unary
      console.log(res, res.getName()); // it works.
    });

  
   const stream = client.sendStream(new Arg()); // server streaming

    stream.on('data', (data) => {
      // although it's running, this won't be executed in browser console. no idea why
      console.log('data', data);
    });

   stream.on('metadata', (metadata) => {
      console.log('metadata', metadata); // this is executed once though. I see it in browser console
    });

  return () => stream.close();
}, []);

Versions

• "google-protobuf": "^3.21.4"
• "grpc-web": "^1.5.0"

[sampajano]

@Gumichocopengin8 Hi thanks for reaching out!

It's hard to tell without seeing the request/response from Envoy v.s. Tonic-web side by side. (It would be great if you could try that tho).

I'm wondering if you could try using the following plugin to see if it can help you determine if the wire formats are looking correct?
https://chromewebstore.google.com/detail/grpc-web-developer-tools/kanmilmfkjnoladbbamlclhccicldjaj

[Gumichocopengin8]

Thanks for the response. I'll try to create a minimal code to see if it works with/without Envoy vs Tonic-web.

[sampajano]

Cool! Thanks! :)

[Gumichocopengin8]

I made a minimal code here with and without Envoy. In both way, stream callback does not work in server streaming with gRPC-Web and Tonic at all with or without Envoy.
But the stream server endpoint works in Postman. it might be a gRPC-web, but I also wanna confirm if server side works with other gRPC for web library like Buf to get rid of the possible issue of Tonic.
I made sure to use mode=grpcwebtext for server streaming.