Quick start

This walks through calling a Greeter service with a unary SayHello RPC, using the tier-2 runtime API (no codegen). Assume this proto:

syntax = "proto3";
package greeter;

service Greeter {
  rpc SayHello (HelloRequest) returns (HelloReply);
}
message HelloRequest { string name = 1; }
message HelloReply   { string message = 1; }

1. Export a descriptor set

godot-grpc reads your schema at runtime from a serialized FileDescriptorSet:

protoc --descriptor_set_out=greeter.descriptor.bin -I proto proto/greeter.proto

Place greeter.descriptor.bin in your project, e.g. res://greeter.descriptor.bin.

2. Call it from GDScript

extends Node

func _ready() -> void:
    var pool := GrpcDescriptorPool.new()
    pool.load_file("res://greeter.descriptor.bin")

    var channel := GrpcChannel.tcp("http://127.0.0.1:50051")
    var stub := pool.service("greeter.Greeter").client(channel)

    var call := stub.unary("SayHello", { "name": "world" })
    call.completed.connect(func(reply): print(reply.get_field("message")))
    call.failed.connect(func(status): push_error(status.message()))

That’s the whole flow: load schema → open channel → bind a service stub → call with a Dictionary, handle the completed/failed signals.

Unix Domain Sockets

Swap the transport — everything else is identical:

var channel := GrpcChannel.uds("/tmp/greeter.sock")

Connections are lazy

GrpcChannel.tcp(...) / .uds(...) return immediately; the connection is established on the first RPC. A bad address or unreachable server surfaces as a failed(status) signal on the call, not at channel-construction time.

Next steps

• Prefer typed req.name = "world" over dicts? See Typed codegen.
• Streaming RPCs: see Streaming.