syntax = "proto3";

//
// This is a protobuf file. This is used by gRPC (and nRPC) to define the interface
//  between the front-end and the back-end. Because the front-end is compiled to
//  WebAssembly and has Javascript bindings, there are a few gotchas:
//
//    - A message cannot contain non-Copy fields unless it only has one field;
//       messages are turned into Rust structs if they have more than one field
//       and all types bound to Javascript must be Copy
//    - A single-field message will not be turned into a single-field struct;
//       the field will be passed around directly instead.
//    - A zero-field message will be turned into an empty tuple ()
//    - JS bindings are similar, except with JS Objects
//    - Values can be streamed back- to front-end with a Rust generator stream and a JS callback function
//    - Values can be streamed front- to back-end with a JS generator function and a Rust stream consumer
//
// The generated Rust module and Typescript bindings should provide a good clue as to how to pass parameters
//

package usdpl_template;

// The most amazing nRPC service
service Template {
  // Send back the exact same message as received
  rpc echo (EchoMessage) returns (EchoMessage);

  // Hello world
  rpc hello (NameMessage) returns (HelloResponse);

  // Service version info
  rpc version (Empty) returns (VersionMessage);

  // Service name
  rpc name (Empty) returns (NameMessage);
}

// The request and response message for Echo
message EchoMessage {
  string msg = 1;
}

message NameMessage {
  string name = 1;
}

message HelloResponse {
  string phrase = 1;
}

message Empty {}

message VersionMessage {
  string version = 1;
}