Add helper library for using typed-rpc with ocaml-protoc-plugin

dune-project

@@ -96,6 +96,17 @@
    (>= 0.9.0))
   stringext))
 
+(package
+ (name grpc-protoc-plugin)
+ (synopsis "An implementation of gRPC using ocaml-protoc-plugin")
+ (description
+  "Functionality for building gRPC services and rpcs with `ocaml-protoc-plugin`")
+ (depends
+  (grpc
+   (= :version))
+  (ocaml-protoc-plugin
+   (>= 4.5))))
+
 (package
  (name grpc-examples)
  (synopsis "Various gRPC examples")

grpc-protoc-plugin.opam

@@ -0,0 +1,40 @@
+# This file is generated by dune, edit dune-project instead
+opam-version: "2.0"
+synopsis: "An implementation of gRPC using ocaml-protoc-plugin"
+description:
+  "Functionality for building gRPC services and rpcs with `ocaml-protoc-plugin`"
+maintainer: ["Daniel Quernheim <[email protected]>"]
+authors: [
+  "Andrew Jeffery <[email protected]>"
+  "Daniel Quernheim <[email protected]>"
+  "Michael Bacarella <[email protected]>"
+  "Sven Anderson <[email protected]>"
+  "Tim McGilchrist <[email protected]>"
+  "Wojtek Czekalski <[email protected]>"
+  "dimitris.mostrous <[email protected]>"
+]
+license: "BSD-3-Clause"
+homepage: "https://github.com/dialohq/ocaml-grpc"
+doc: "https://dialohq.github.io/ocaml-grpc"
+bug-reports: "https://github.com/dialohq/ocaml-grpc/issues"
+depends: [
+  "dune" {>= "3.7"}
+  "grpc" {= version}
+  "ocaml-protoc-plugin" {>= "4.5"}
+  "odoc" {with-doc}
+]
+build: [
+  ["dune" "subst"] {dev}
+  [
+    "dune"
+    "build"
+    "-p"
+    name
+    "-j"
+    jobs
+    "@install"
+    "@runtest" {with-test}
+    "@doc" {with-doc}
+  ]
+]
+dev-repo: "git+https://github.com/dialohq/ocaml-grpc.git"

lib/grpc-protoc-plugin/dune

@@ -0,0 +1,4 @@
+(library
+ (name grpc_protoc_plugin)
+ (public_name grpc-protoc-plugin)
+ (libraries grpc ocaml-protoc-plugin))

lib/grpc-protoc-plugin/grpc_protoc_plugin.ml

@@ -0,0 +1,69 @@
+module type S = Ocaml_protoc_plugin.Service.Rpc
+
+let encode (type a)
+    (module M : Ocaml_protoc_plugin.Runtime.Runtime'.Service.Message
+      with type t = a) (a : a) =
+  a |> M.to_proto |> Ocaml_protoc_plugin.Runtime.Runtime'.Writer.contents
+
+let decode (type a)
+    (module M : Ocaml_protoc_plugin.Runtime.Runtime'.Service.Message
+      with type t = a) buffer =
+  buffer |> Ocaml_protoc_plugin.Runtime.Runtime'.Reader.create |> M.from_proto
+  |> function
+  | Ok r -> r
+  | Error e ->
+      failwith
+        (Printf.sprintf "Could not decode request: %s"
+           (Ocaml_protoc_plugin.Result.show_error e))
+
+let service_spec (type request response)
+    (module R : S with type Request.t = request and type Response.t = response)
+    =
+  {
+    Grpc.Rpc.Service_spec.package = R.package_name |> Option.to_list;
+    service_name = R.service_name;
+  }
+
+module Client_rpc = struct
+  let make (type request response)
+      (module R : S with type Request.t = request and type Response.t = response)
+      ~request_mode ~response_mode =
+    {
+      Grpc.Rpc.Client_rpc.service_spec = service_spec (module R);
+      rpc_name = R.method_name;
+      encode_request = encode (module R.Request);
+      decode_response = decode (module R.Response);
+      request_mode;
+      response_mode;
+    }
+
+  let unary rpc = make rpc ~request_mode:Unary ~response_mode:Unary
+  let client_streaming rpc = make rpc ~request_mode:Stream ~response_mode:Unary
+  let server_streaming rpc = make rpc ~request_mode:Unary ~response_mode:Stream
+
+  let bidirectional_streaming rpc =
+    make rpc ~request_mode:Stream ~response_mode:Stream
+end
+
+module Server_rpc = struct
+  let make (type request response)
+      (module R : S with type Request.t = request and type Response.t = response)
+      ~request_mode ~response_mode =
+    {
+      Grpc.Rpc.Server_rpc.service_spec = Some (service_spec (module R));
+      rpc_name = R.method_name;
+      decode_request = decode (module R.Request);
+      encode_response = encode (module R.Response);
+      request_mode;
+      response_mode;
+    }
+
+  let unary rpc = make rpc ~request_mode:Unary ~response_mode:Unary
+  let client_streaming rpc = make rpc ~request_mode:Stream ~response_mode:Unary
+  let server_streaming rpc = make rpc ~request_mode:Unary ~response_mode:Stream
+
+  let bidirectional_streaming rpc =
+    make rpc ~request_mode:Stream ~response_mode:Stream
+end
+
+let handlers handlers = Grpc.Rpc.Handlers.Handlers { handlers }

lib/grpc-protoc-plugin/grpc_protoc_plugin.mli

@@ -0,0 +1,92 @@
+(** A utility library for constructing gRPC specifications using
+    [Ocaml_protoc_plugin].
+
+    This module is designed to work alongside [Ocaml_protoc_plugin] to generate
+    gRPC stubs, as outlined in {!module:Grpc.Rpc}. It offers a collection of
+    helper functions that construct gRPC specifications from the code produced
+    by [Ocaml_protoc_plugin] based on the services defined in *.proto files. *)
+
+module type S = Ocaml_protoc_plugin.Service.Rpc
+(** For each service delineated in *.proto files, [Ocaml_protoc_plugin]
+    generates a module that conforms to the type interface [S]. This module
+    serves as the entry point for this library to create the corresponding
+    gRPC specifications on the client and server sides. It is to be supplied
+    to the corresponding helper as a first class module parameter. *)
+
+(** {1 Client side} *)
+
+module Client_rpc : sig
+  val unary :
+    (module S with type Request.t = 'request and type Response.t = 'response) ->
+    ( 'request,
+      Grpc.Rpc.Value_mode.unary,
+      'response,
+      Grpc.Rpc.Value_mode.unary )
+    Grpc.Rpc.Client_rpc.t
+
+  val client_streaming :
+    (module S with type Request.t = 'request and type Response.t = 'response) ->
+    ( 'request,
+      Grpc.Rpc.Value_mode.stream,
+      'response,
+      Grpc.Rpc.Value_mode.unary )
+    Grpc.Rpc.Client_rpc.t
+
+  val server_streaming :
+    (module S with type Request.t = 'request and type Response.t = 'response) ->
+    ( 'request,
+      Grpc.Rpc.Value_mode.unary,
+      'response,
+      Grpc.Rpc.Value_mode.stream )
+    Grpc.Rpc.Client_rpc.t
+
+  val bidirectional_streaming :
+    (module S with type Request.t = 'request and type Response.t = 'response) ->
+    ( 'request,
+      Grpc.Rpc.Value_mode.stream,
+      'response,
+      Grpc.Rpc.Value_mode.stream )
+    Grpc.Rpc.Client_rpc.t
+end
+
+(** {1 Server side} *)
+
+module Server_rpc : sig
+  val unary :
+    (module S with type Request.t = 'request and type Response.t = 'response) ->
+    ( 'request,
+      Grpc.Rpc.Value_mode.unary,
+      'response,
+      Grpc.Rpc.Value_mode.unary,
+      Grpc.Rpc.Service_spec.t )
+    Grpc.Rpc.Server_rpc.t
+
+  val client_streaming :
+    (module S with type Request.t = 'request and type Response.t = 'response) ->
+    ( 'request,
+      Grpc.Rpc.Value_mode.stream,
+      'response,
+      Grpc.Rpc.Value_mode.unary,
+      Grpc.Rpc.Service_spec.t )
+    Grpc.Rpc.Server_rpc.t
+
+  val server_streaming :
+    (module S with type Request.t = 'request and type Response.t = 'response) ->
+    ( 'request,
+      Grpc.Rpc.Value_mode.unary,
+      'response,
+      Grpc.Rpc.Value_mode.stream,
+      Grpc.Rpc.Service_spec.t )
+    Grpc.Rpc.Server_rpc.t
+
+  val bidirectional_streaming :
+    (module S with type Request.t = 'request and type Response.t = 'response) ->
+    ( 'request,
+      Grpc.Rpc.Value_mode.stream,
+      'response,
+      Grpc.Rpc.Value_mode.stream,
+      Grpc.Rpc.Service_spec.t )
+    Grpc.Rpc.Server_rpc.t
+end
+
+val handlers : 'a list -> ('a, _) Grpc.Rpc.Handlers.t