02 The streaming proto

Open greeter.proto from the beginner tier and add the SayHellos method. The keyword stream before the return type marks it as server-streaming.

syntax = "proto3";

package greeter;

service Greeter {
  rpc SayHello (HelloRequest) returns (HelloReply) {}
  rpc SayHellos (HelloRequest) returns (stream HelloReply) {}
}

message HelloRequest {
  string name = 1;
}

message HelloReply {
  string message = 1;
}

What changed

Before	After
One SayHello RPC	SayHello + SayHellos
returns (HelloReply)	returns (stream HelloReply)

The stream keyword is the only proto change. The message types are identical — SayHellos reuses HelloRequest and HelloReply. No other file needs to change for the proto definition.

Because @grpc/proto-loader loads the .proto at runtime, no code-generation step is needed. The server and client pick up the new method as soon as they require('./load').

Next: 03 The streaming server