03 The streaming server

Add the sayHellos handler to server.js and register it alongside sayHello.

// server.js
const { grpc, proto } = require("./load");

function sayHello(call, callback) {
  callback(null, { message: `Hello, ${call.request.name}` });
}

function sayHellos(call) {
  const name = call.request.name;
  for (const g of ["Hello", "Hi", "Hey"]) {
    call.write({ message: `${g}, ${name}` });
  }
  call.end();
}

const server = new grpc.Server();
server.addService(proto.Greeter.service, {
  SayHello: sayHello,
  SayHellos: sayHellos,
});
server.bindAsync(
  "0.0.0.0:50051",
  grpc.ServerCredentials.createInsecure(),
  () => console.log("Greeter listening on :50051"),
);

How sayHellos works

Line	What it does
function sayHellos(call)	Streaming handlers take only call — no callback.
call.request.name	The client's HelloRequest.name, same as in unary.
call.write({ message })	Pushes one HelloReply to the client. May be called many times.
call.end()	Signals the stream is complete. The client receives an end event.

The addService call now maps both methods. gRPC routes each incoming RPC to the correct handler by method name.

Checkpoint

Start the server:

node server.js
# Greeter listening on :50051

The server should start without errors. Leave it running for the next page.

Next: 04 The streaming client