05 The client

Create client.js:

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

const client = new proto.Greeter(
  "localhost:50051",
  grpc.credentials.createInsecure(),
);

client.SayHello({ name: "Ada" }, (err, response) => {
  if (err) throw err;
  console.log(response.message);
});

How it works:

Line	What it does
`require("./load")`	Same `grpc` + `proto` bindings used by the server.
`new proto.Greeter(...)`	Creates a stub connected to `localhost:50051`. `proto.Greeter` is a client constructor generated from the service definition.
`createInsecure()`	No TLS — matches the server's `createInsecure()` credentials.
`client.SayHello(...)`	Sends a `HelloRequest` with `name: "Ada"`. The callback receives `(err, response)` where `response` is the deserialized `HelloReply`.
`console.log(response.message)`	Prints the `message` field — you'll see `Hello, Ada`.

The client connects lazily: the channel is created immediately but the underlying TCP connection to port 50051 is established on the first call.

Next: 06 Run and inspect

05 The client ​

05 The client