feat: http transcoding grpc

codegen/src/main/twirl/templates/ScalaServer/Handler.scala.txt

@@ -11,6 +11,7 @@ import scala.concurrent.ExecutionContext
 
 import akka.grpc.scaladsl.{ GrpcExceptionHandler, GrpcMarshalling }
 import akka.grpc.Trailers
+import akka.grpc.HttpApi
 
 import akka.actor.ActorSystem
 import akka.actor.ClassicActorSystemProvider
@@ -128,12 +129,24 @@ object @{serviceName}Handler {
           .recoverWith(GrpcExceptionHandler.from(eHandler(system.classicSystem))(system, writer))
       ).getOrElse(unsupportedMediaType)
 
-      Function.unlift((req: model.HttpRequest) => req.uri.path match {
+     @for(method <- service.methods if !method.inputStreaming) {
+      lazy val @{method.name}Handler = @if(method.outputStreaming) {
+             HttpApi.getSourceHandler@{if(powerApis) "PowerApi" else ""}("@{method.name}", @{service.name}.descriptor, implementation.@{method.nameSafe})
+               } else {
+             HttpApi.getHttpFutureHandler@{if(powerApis) "PowerApi" else ""}("@{method.name}", @{service.name}.descriptor, implementation.@{method.nameSafe})
+               }
+     }
+
+      val httpApiHandlers = (List.empty[PartialFunction[model.HttpRequest, scala.concurrent.Future[model.HttpResponse]]]  @for(method <- service.methods if !method.inputStreaming){ ++ @{method.name}Handler})
+        .foldLeft(PartialFunction.empty[model.HttpRequest, scala.concurrent.Future[model.HttpResponse]])((acc, p) => acc.orElse(p))
+
+      val grpcHandlers = Function.unlift((req: model.HttpRequest) => req.uri.path match {
         case model.Uri.Path.Slash(model.Uri.Path.Segment(`prefix`, model.Uri.Path.Slash(model.Uri.Path.Segment(method, model.Uri.Path.Empty)))) =>
           Some(handle(spi.onRequest(prefix, method, req), method))
         case _ =>
           None
       })
+      httpApiHandlers orElse grpcHandlers
     }
   }
 }

project/Dependencies.scala

@@ -79,6 +79,7 @@ object Dependencies {
 
   object Protobuf {
     val protobufJava = "com.google.protobuf" % "protobuf-java" % Versions.googleProtobuf
+    val protobufJavaUtil = "com.google.protobuf" % "protobuf-java-util" % Versions.googleProtobuf
     val googleCommonProtos = "com.google.protobuf" % "protobuf-java" % Versions.googleProtobuf % "protobuf"
   }
 
@@ -100,6 +101,7 @@ object Dependencies {
   val runtime = l ++= Seq(
     Compile.scalapbRuntime,
     Protobuf.protobufJava, // or else scalapb pulls older version in transitively
+    Protobuf.protobufJavaUtil,
     Compile.grpcCore,
     Compile.grpcStub % "provided", // comes from the generators
     Compile.grpcNettyShaded,

runtime/src/main/protobuf/google/api/annotations.proto

@@ -0,0 +1,31 @@
+// Copyright 2015 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+syntax = "proto3";
+
+package google.api;
+
+import "google/api/http.proto";
+import "google/protobuf/descriptor.proto";
+
+option go_package = "google.golang.org/genproto/googleapis/api/annotations;annotations";
+option java_multiple_files = true;
+option java_outer_classname = "AnnotationsProto";
+option java_package = "com.google.api";
+option objc_class_prefix = "GAPI";
+
+extend google.protobuf.MethodOptions {
+  // See `HttpRule`.
+  HttpRule http = 72295728;
+}