enforce consistency of request and response modes

- This adds type safety to ensure the RPCs are called with the
  expected protocol (e.g. you cannot call a unary rpc with a
  server_streaming entry point, etc.).

On the ocaml-protoc-plugin side, currently there are no markers for
the rpc modes - this interface will permit adding them in the future
without user facing changes.

On the ocaml-protoc plugin, the value mode flows from the proto file
definition and is checked in the user code as expected.

Implementation note: There's perhaps a way to shorten the mapping of
value-modes but I couldn't find one given that `Grpc` cannot depend on
`Ocaml_protoc`, and thus the `Value_mode` types are not equal.

examples/greeter-client-eio/greeter_client_eio.ml

@@ -30,7 +30,7 @@ let main env =
 
     let result =
       Grpc_eio.Client.Typed_rpc.call
-        (Grpc_protoc_plugin.client_rpc (module Greeter.SayHello))
+        (Grpc_protoc_plugin.Client_rpc.unary (module Greeter.SayHello))
         ~do_request:(H2_eio.Client.request connection ~error_handler:ignore)
         ~handler:(Grpc_eio.Client.Typed_rpc.unary request ~f)
         ()

examples/greeter-protoc-client-eio/greeter_client_eio.ml

@@ -29,7 +29,8 @@ let main env =
 
     let result =
       Grpc_eio.Client.Typed_rpc.call
-        (Grpc_protoc.client_rpc Greeter_protoc.Greeter.Greeter.Client.sayHello)
+        (Grpc_protoc.Client_rpc.unary
+           Greeter_protoc.Greeter.Greeter.Client.sayHello)
         ~do_request:(H2_eio.Client.request connection ~error_handler:ignore)
         ~handler:(Grpc_eio.Client.Typed_rpc.unary request ~f)
         ()

examples/greeter-protoc-server-eio/greeter_server_eio.ml

@@ -1,7 +1,7 @@
 open Grpc_eio
 
 let sayHello rpc =
-  Grpc_eio.Server.Typed_rpc.unary (Grpc_protoc.server_rpc rpc)
+  Grpc_eio.Server.Typed_rpc.unary (Grpc_protoc.Server_rpc.unary rpc)
     ~f:(fun (request : Greeter_protoc.Greeter.hello_request) ->
       let message =
         if request.name = "" then "You forgot your name!"
@@ -52,11 +52,8 @@ let serve server env =
 
 let () =
   let server =
-    let { Pbrt_services.Server.package; service_name; handlers } =
-      Greeter_protoc.Greeter.Greeter.Server.make ~sayHello ()
-    in
-    Server.Typed_rpc.server
-      (With_service_spec { package; service_name; handlers })
+    Greeter_protoc.Greeter.Greeter.Server.make ~sayHello ()
+    |> Grpc_protoc.handlers |> Server.Typed_rpc.server
   in
 
   Eio_main.run (serve server)

examples/greeter-server-eio/greeter_server_eio.ml

@@ -3,7 +3,7 @@ open Grpc_eio
 let say_hello =
   let module SayHello = Greeter.Mypackage.Greeter.SayHello in
   Grpc_eio.Server.Typed_rpc.unary
-    (Grpc_protoc_plugin.server_rpc (module SayHello))
+    (Grpc_protoc_plugin.Server_rpc.unary (module SayHello))
     ~f:(fun request ->
       let message =
         if request = "" then "You forgot your name!"
@@ -53,6 +53,8 @@ let serve server env =
   listen ()
 
 let () =
-  let server = Server.Typed_rpc.server (Handlers [ say_hello ]) in
+  let server =
+    Server.Typed_rpc.server (Grpc_protoc_plugin.handlers [ say_hello ])
+  in
 
   Eio_main.run (serve server)

examples/routeguide-protoc/src/client.ml

@@ -21,7 +21,7 @@ let client ~sw host port network =
 let call_get_feature connection point =
   let response =
     Client.Typed_rpc.call
-      (Grpc_protoc.client_rpc Route_guide.RouteGuide.Client.getFeature)
+      (Grpc_protoc.Client_rpc.unary Route_guide.RouteGuide.Client.getFeature)
       ~do_request:(H2_eio.Client.request connection ~error_handler:ignore)
       ~handler:
         (Client.Typed_rpc.unary point ~f:(function
@@ -52,7 +52,8 @@ let print_features connection =
 
   let stream =
     Client.Typed_rpc.call
-      (Grpc_protoc.client_rpc Route_guide.RouteGuide.Client.listFeatures)
+      (Grpc_protoc.Client_rpc.server_streaming
+         Route_guide.RouteGuide.Client.listFeatures)
       ~do_request:(H2_eio.Client.request connection ~error_handler:ignore)
       ~handler:(Client.Typed_rpc.server_streaming rectangle ~f:Fun.id)
       ()
@@ -82,7 +83,8 @@ let run_record_route connection =
 
   let response =
     Client.Typed_rpc.call
-      (Grpc_protoc.client_rpc Route_guide.RouteGuide.Client.recordRoute)
+      (Grpc_protoc.Client_rpc.client_streaming
+         Route_guide.RouteGuide.Client.recordRoute)
       ~do_request:(H2_eio.Client.request connection ~error_handler:ignore)
       ~handler:
         (Client.Typed_rpc.client_streaming ~f:(fun f response ->
@@ -144,7 +146,8 @@ let run_route_chat clock connection =
   in
   let result =
     Client.Typed_rpc.call
-      (Grpc_protoc.client_rpc Route_guide.RouteGuide.Client.routeChat)
+      (Grpc_protoc.Client_rpc.bidirectional_streaming
+         Route_guide.RouteGuide.Client.routeChat)
       ~do_request:(H2_eio.Client.request connection ~error_handler:ignore)
       ~handler:
         (Client.Typed_rpc.bidirectional_streaming ~f:(fun writer reader ->

examples/routeguide-protoc/src/server.ml

@@ -77,7 +77,8 @@ let calc_distance (p1 : Route_guide.point) (p2 : Route_guide.point) : int =
 
 (* $MDX part-begin=server-get-feature *)
 let get_feature (t : t) rpc =
-  Grpc_eio.Server.Typed_rpc.unary (Grpc_protoc.server_rpc rpc) ~f:(fun point ->
+  Grpc_eio.Server.Typed_rpc.unary (Grpc_protoc.Server_rpc.unary rpc)
+    ~f:(fun point ->
       Eio.traceln "GetFeature = {:%a}" Route_guide.pp_point point;
 
       (* Lookup the feature and if found return it. *)
@@ -103,8 +104,8 @@ let get_feature (t : t) rpc =
 (* $MDX part-end *)
 (* $MDX part-begin=server-list-features *)
 let list_features (t : t) rpc =
-  Grpc_eio.Server.Typed_rpc.server_streaming (Grpc_protoc.server_rpc rpc)
-    ~f:(fun rectangle f ->
+  Grpc_eio.Server.Typed_rpc.server_streaming
+    (Grpc_protoc.Server_rpc.server_streaming rpc) ~f:(fun rectangle f ->
       (* Lookup and reply with features found. *)
       let () =
         List.iter
@@ -118,7 +119,8 @@ let list_features (t : t) rpc =
 (* $MDX part-end *)
 (* $MDX part-begin=server-record-route *)
 let record_route (t : t) (clock : _ Eio.Time.clock) rpc =
-  Grpc_eio.Server.Typed_rpc.client_streaming (Grpc_protoc.server_rpc rpc)
+  Grpc_eio.Server.Typed_rpc.client_streaming
+    (Grpc_protoc.Server_rpc.client_streaming rpc)
     ~f:(fun (stream : Route_guide.point Seq.t) ->
       Eio.traceln "RecordRoute";
 
@@ -168,7 +170,8 @@ let record_route (t : t) (clock : _ Eio.Time.clock) rpc =
 (* $MDX part-end *)
 (* $MDX part-begin=server-route-chat *)
 let route_chat (_ : t) rpc =
-  Grpc_eio.Server.Typed_rpc.bidirectional_streaming (Grpc_protoc.server_rpc rpc)
+  Grpc_eio.Server.Typed_rpc.bidirectional_streaming
+    (Grpc_protoc.Server_rpc.bidirectional_streaming rpc)
     ~f:(fun
          (stream : Route_guide.route_note Seq.t)
          (f : Route_guide.route_note -> unit)
@@ -187,13 +190,10 @@ let route_chat (_ : t) rpc =
 (* $MDX part-end *)
 (* $MDX part-begin=server-grpc *)
 let server t clock =
-  let { Pbrt_services.Server.package; service_name; handlers } =
-    Route_guide.RouteGuide.Server.make ~getFeature:(get_feature t)
-      ~listFeatures:(list_features t) ~recordRoute:(record_route t clock)
-      ~routeChat:(route_chat t) ()
-  in
-  Server.Typed_rpc.server
-    (With_service_spec { package; service_name; handlers })
+  Route_guide.RouteGuide.Server.make ~getFeature:(get_feature t)
+    ~listFeatures:(list_features t) ~recordRoute:(record_route t clock)
+    ~routeChat:(route_chat t) ()
+  |> Grpc_protoc.handlers |> Server.Typed_rpc.server
 
 (* $MDX part-end *)
 let connection_handler server ~sw =

examples/routeguide-tutorial.md

@@ -194,7 +194,7 @@ The individual service functions from our proto definition are implemented using
 ```ocaml
 let server t clock =
   Server.Typed_rpc.server
-    (Handlers
+    (Grpc_protoc_plugin.handlers
        [ get_feature t; list_features t; record_route t clock; route_chat t ])
 ```
 
@@ -206,7 +206,7 @@ Let's look at the simplest type first, `GetFeature` which just gets a `Point` fr
 ```ocaml
 let get_feature (t : t) =
   Grpc_eio.Server.Typed_rpc.unary
-    (Grpc_protoc_plugin.server_rpc (module RouteGuide.GetFeature))
+    (Grpc_protoc_plugin.Server_rpc.unary (module RouteGuide.GetFeature))
     ~f:(fun point ->
       Eio.traceln "GetFeature = {:%s}" (Point.show point);
 
@@ -238,7 +238,8 @@ Now let's look at one of our streaming RPCs. `list_features` is a server-side st
 ```ocaml
 let list_features (t : t) =
   Grpc_eio.Server.Typed_rpc.server_streaming
-    (Grpc_protoc_plugin.server_rpc (module RouteGuide.ListFeatures))
+    (Grpc_protoc_plugin.Server_rpc.server_streaming
+       (module RouteGuide.ListFeatures))
     ~f:(fun rectangle f ->
       (* Lookup and reply with features found. *)
       let () =
@@ -261,7 +262,8 @@ Now let's look at something a little more complicated: the client-side streaming
 ```ocaml
 let record_route (t : t) (clock : _ Eio.Time.clock) =
   Grpc_eio.Server.Typed_rpc.client_streaming
-    (Grpc_protoc_plugin.server_rpc (module RouteGuide.RecordRoute))
+    (Grpc_protoc_plugin.Server_rpc.client_streaming
+       (module RouteGuide.RecordRoute))
     ~f:(fun (stream : Point.t Seq.t) ->
       Eio.traceln "RecordRoute";
 
@@ -312,7 +314,8 @@ Finally, let's look at our bidirectional streaming RPC `route_chat`, which recei
 ```ocaml
 let route_chat (_ : t) =
   Grpc_eio.Server.Typed_rpc.bidirectional_streaming
-    (Grpc_protoc_plugin.server_rpc (module RouteGuide.RouteChat))
+    (Grpc_protoc_plugin.Server_rpc.bidirectional_streaming
+       (module RouteGuide.RouteChat))
     ~f:(fun (stream : RouteNote.t Seq.t) (f : RouteNote.t -> unit) ->
       Printf.printf "RouteChat\n";
 
@@ -401,7 +404,7 @@ Calling the simple RPC `get_feature` requires building up a `Client.call` repres
 let call_get_feature connection point =
   let response =
     Client.Typed_rpc.call
-      (Grpc_protoc_plugin.client_rpc (module RouteGuide.GetFeature))
+      (Grpc_protoc_plugin.Client_rpc.unary (module RouteGuide.GetFeature))
       ~do_request:(H2_eio.Client.request connection ~error_handler:ignore)
       ~handler:
         (Client.Typed_rpc.unary point ~f:(function
@@ -429,7 +432,8 @@ let print_features connection =
 
   let stream =
     Client.Typed_rpc.call
-      (Grpc_protoc_plugin.client_rpc (module RouteGuide.ListFeatures))
+      (Grpc_protoc_plugin.Client_rpc.server_streaming
+         (module RouteGuide.ListFeatures))
       ~do_request:(H2_eio.Client.request connection ~error_handler:ignore)
       ~handler:(Client.Typed_rpc.server_streaming rectangle ~f:Fun.id)
       ()
@@ -466,7 +470,8 @@ let run_record_route connection =
 
   let response =
     Client.Typed_rpc.call
-      (Grpc_protoc_plugin.client_rpc (module RouteGuide.RecordRoute))
+      (Grpc_protoc_plugin.Client_rpc.client_streaming
+         (module RouteGuide.RecordRoute))
       ~do_request:(H2_eio.Client.request connection ~error_handler:ignore)
       ~handler:
         (Client.Typed_rpc.client_streaming ~f:(fun f response ->
@@ -535,7 +540,8 @@ We start by generating a short sequence of locations, similar to how we did for
   in
   let result =
     Client.Typed_rpc.call
-      (Grpc_protoc_plugin.client_rpc (module RouteGuide.RouteChat))
+      (Grpc_protoc_plugin.Client_rpc.bidirectional_streaming
+         (module RouteGuide.RouteChat))
       ~do_request:(H2_eio.Client.request connection ~error_handler:ignore)
       ~handler:
         (Client.Typed_rpc.bidirectional_streaming ~f:(fun writer reader ->

examples/routeguide/src/client.ml

@@ -21,7 +21,7 @@ let client ~sw host port network =
 let call_get_feature connection point =
   let response =
     Client.Typed_rpc.call
-      (Grpc_protoc_plugin.client_rpc (module RouteGuide.GetFeature))
+      (Grpc_protoc_plugin.Client_rpc.unary (module RouteGuide.GetFeature))
       ~do_request:(H2_eio.Client.request connection ~error_handler:ignore)
       ~handler:
         (Client.Typed_rpc.unary point ~f:(function
@@ -45,7 +45,8 @@ let print_features connection =
 
   let stream =
     Client.Typed_rpc.call
-      (Grpc_protoc_plugin.client_rpc (module RouteGuide.ListFeatures))
+      (Grpc_protoc_plugin.Client_rpc.server_streaming
+         (module RouteGuide.ListFeatures))
       ~do_request:(H2_eio.Client.request connection ~error_handler:ignore)
       ~handler:(Client.Typed_rpc.server_streaming rectangle ~f:Fun.id)
       ()
@@ -75,7 +76,8 @@ let run_record_route connection =
 
   let response =
     Client.Typed_rpc.call
-      (Grpc_protoc_plugin.client_rpc (module RouteGuide.RecordRoute))
+      (Grpc_protoc_plugin.Client_rpc.client_streaming
+         (module RouteGuide.RecordRoute))
       ~do_request:(H2_eio.Client.request connection ~error_handler:ignore)
       ~handler:
         (Client.Typed_rpc.client_streaming ~f:(fun f response ->
@@ -135,7 +137,8 @@ let run_route_chat clock connection =
   in
   let result =
     Client.Typed_rpc.call
-      (Grpc_protoc_plugin.client_rpc (module RouteGuide.RouteChat))
+      (Grpc_protoc_plugin.Client_rpc.bidirectional_streaming
+         (module RouteGuide.RouteChat))
       ~do_request:(H2_eio.Client.request connection ~error_handler:ignore)
       ~handler:
         (Client.Typed_rpc.bidirectional_streaming ~f:(fun writer reader ->

examples/routeguide/src/server.ml

@@ -75,7 +75,7 @@ let calc_distance (p1 : Point.t) (p2 : Point.t) : int =
 (* $MDX part-begin=server-get-feature *)
 let get_feature (t : t) =
   Grpc_eio.Server.Typed_rpc.unary
-    (Grpc_protoc_plugin.server_rpc (module RouteGuide.GetFeature))
+    (Grpc_protoc_plugin.Server_rpc.unary (module RouteGuide.GetFeature))
     ~f:(fun point ->
       Eio.traceln "GetFeature = {:%s}" (Point.show point);
 
@@ -100,7 +100,8 @@ let get_feature (t : t) =
 (* $MDX part-begin=server-list-features *)
 let list_features (t : t) =
   Grpc_eio.Server.Typed_rpc.server_streaming
-    (Grpc_protoc_plugin.server_rpc (module RouteGuide.ListFeatures))
+    (Grpc_protoc_plugin.Server_rpc.server_streaming
+       (module RouteGuide.ListFeatures))
     ~f:(fun rectangle f ->
       (* Lookup and reply with features found. *)
       let () =
@@ -116,7 +117,8 @@ let list_features (t : t) =
 (* $MDX part-begin=server-record-route *)
 let record_route (t : t) (clock : _ Eio.Time.clock) =
   Grpc_eio.Server.Typed_rpc.client_streaming
-    (Grpc_protoc_plugin.server_rpc (module RouteGuide.RecordRoute))
+    (Grpc_protoc_plugin.Server_rpc.client_streaming
+       (module RouteGuide.RecordRoute))
     ~f:(fun (stream : Point.t Seq.t) ->
       Eio.traceln "RecordRoute";
 
@@ -162,7 +164,8 @@ let record_route (t : t) (clock : _ Eio.Time.clock) =
 (* $MDX part-begin=server-route-chat *)
 let route_chat (_ : t) =
   Grpc_eio.Server.Typed_rpc.bidirectional_streaming
-    (Grpc_protoc_plugin.server_rpc (module RouteGuide.RouteChat))
+    (Grpc_protoc_plugin.Server_rpc.bidirectional_streaming
+       (module RouteGuide.RouteChat))
     ~f:(fun (stream : RouteNote.t Seq.t) (f : RouteNote.t -> unit) ->
       Printf.printf "RouteChat\n";
 
@@ -179,7 +182,7 @@ let route_chat (_ : t) =
 (* $MDX part-begin=server-grpc *)
 let server t clock =
   Server.Typed_rpc.server
-    (Handlers
+    (Grpc_protoc_plugin.handlers
        [ get_feature t; list_features t; record_route t clock; route_chat t ])
 
 (* $MDX part-end *)