Reflection based implementation (#32)

* GrpcJsonBridge for multiple services * Reflection based implementation (macros removed) * ExecutionContext used in public API * Monix dependency removed
avast · May 22, 2019 · 1c61764 · 1c61764
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diff --git a/README.md b/README.md
@@ -3,131 +3,105 @@
 [![Build Status](https://travis-ci.org/avast/grpc-json-bridge.svg?branch=master)](https://travis-ci.org/avast/grpc-json-bridge)
 [![Download](https://api.bintray.com/packages/avast/maven/grpc-json-bridge/images/download.svg) ](https://bintray.com/avast/maven/grpc-json-bridge/_latestVersion)
 
-This library makes possible to receive a JSON encoded request to a gRPC service. It provides an implementation-agnostic module for mapping to
-your favorite HTTP server as well as few implementations for direct usage in some well-known HTTP servers.  
-For requests/responses mapping a [standard GPB <-> JSON mapping](https://developers.google.com/protocol-buffers/docs/proto3#json) is used.
+This library allows to make a JSON encoded request to a gRPC service. It provides an implementation-agnostic module for mapping to your favorite HTTP server (`core`) as well as few implementations for direct usage in some well-known HTTP servers.  
 
-It uses Scala macros for creating mapping between runtime-provided service and method names to pregenerated Java gRPC classes. In case you
-don't want to use _plain Java API_ you can easily use it together with [Cactus](https://github.com/avast/cactus).
+[Standard GPB <-> JSON mapping](https://developers.google.com/protocol-buffers/docs/proto3#json) is used.
 
-The API is _finally tagless_ (read more e.g. [here](https://www.beyondthelines.net/programming/introduction-to-tagless-final/))
-meaning it can use whatever [`F[_]: cats.effect.Effect`](https://typelevel.org/cats-effect/typeclasses/effect.html)
-(e.g. `cats.effect.IO`, `monix.eval.Task`).
+The API is _finally tagless_ (read more e.g. [here](https://www.beyondthelines.net/programming/introduction-to-tagless-final/)) meaning it can use whatever [`F[_]: cats.effect.Effect`](https://typelevel.org/cats-effect/typeclasses/effect.html) (e.g. `cats.effect.IO`, `monix.eval.Task`).
 
-There are several modules:
-1. core - for basic implementation-agnostic usage
-1. [http4s](http4s) - integration with [http4s](https://http4s.org/) webserver
-1. [akka-http](akka-http) - integration with [Akka Http](https://doc.akka.io/docs/akka-http/current/server-side/index.html) webserver
+## Usage
 
-The created [`GrpcJsonBridge`](core/src/main/scala/com/avast/grpc/jsonbridge/GrpcJsonBridge.scala) exposes not only the methods itself but
-also provides their list to make possible to implement an _info_ endpoint (which is already implemented in server-agnostic implementations).
-
-Recommended URL pattern for exposing the service (and the one used in provided implementations) is `/$SERVICENAME/$METHOD` name and the http
-method is obviously `POST`. The _info_ endpoint is supposed to be exposed on the `/$SERVICENAME` URL and available with `GET` request.
-
-The bridge passes all received headers from JSON request to the gRPC service so it's not any problem to use it e.g. authentication.
-
-## Core module
-
-### Dependency
-
-#### Gradle
 ```groovy
 compile 'com.avast.grpc:grpc-json-bridge-core_2.12:x.x.x'
 ```
-
-#### SBT
 ```scala
 libraryDependencies += "com.avast.grpc" %% "grpc-json-bridge-core" % "x.x.x"
 ```
 
-### Usage
-
-Having a proto like
 ```proto
-option java_package = "com.avast.grpc.jsonbridge.test";
-
-message TestApi {
-    message GetRequest {
-        repeated string names = 1;           // REQUIRED
-    }
-    
-    message GetResponse {
-        map<string, int32> results = 1;      // REQUIRED
-    }
-}
+syntax = "proto3";
+package com.avast.grpc.jsonbridge.test;
 
-service TestApiService {
-    rpc Get (TestApi.GetRequest) returns (TestApi.GetResponse) {}
+service TestService {
+    rpc Add (AddParams) returns (AddResponse) {}
 }
-```
-you can create [`GrpcJsonBridge`](core/src/main/scala/com/avast/grpc/jsonbridge/GrpcJsonBridge.scala) instance by
-```scala
-import com.avast.grpc.jsonbridge._ // this does the magic!
 
-import scala.concurrent.ExecutionContextExecutorService
-import com.avast.grpc.jsonbridge.test.TestApi
-import com.avast.grpc.jsonbridge.test.TestApi.{GetRequest, GetResponse}
-import com.avast.grpc.jsonbridge.test.TestApiServiceGrpc.{TestApiServiceFutureStub, TestApiServiceImplBase}
-import io.grpc.stub.StreamObserver
-
-implicit val executor: ExecutionContextExecutorService = ???
+message AddParams {
+    int32 a = 1;
+    int32 b = 2;
+}
 
-val service = new TestApiServiceImplBase {
-                override def get(request: GetRequest, responseObserver: StreamObserver[TestApi.GetResponse]): Unit = {
-                  responseObserver.onNext(GetResponse.newBuilder().putResults("name", 42).build())
-                  responseObserver.onCompleted()
-                }
-              }
-val bridge = service.createGrpcJsonBridge[Task, TestApiServiceFutureStub]() // this does the magic!
+message AddResponse {
+    int32 sum = 1;
+}
 ```
-or you can even go with the [Cactus](https://github.com/avast/cactus) and let it map the GPB messages to your case classes:
 ```scala
-import com.avast.grpc.jsonbridge._ // import for the grpc-json-bridge mapping
-import com.avast.cactus.grpc._
-import com.avast.cactus.grpc.server._ // import for the cactus mapping
+import com.avast.grpc.jsonbridge.ReflectionGrpcJsonBridge
 
-import com.avast.grpc.jsonbridge.test.TestApiServiceGrpc.{TestApiServiceFutureStub, TestApiServiceImplBase}
-import io.grpc.Status
+// for whole server
+val grpcServer: io.grpc.Server = ???
+val bridge = new ReflectionGrpcJsonBridge[Task](grpcServer)
 
-import scala.concurrent.{ExecutionContextExecutorService, Future}
+// or for selected services
+val s1: ServerServiceDefinition = ???
+val s2: ServerServiceDefinition = ???
+val anotherBridge = new ReflectionGrpcJsonBridge[Task](s1, s2)
 
-implicit val executor: ExecutionContextExecutorService = ???
+// call a method manually, with a header specified
+val jsonResponse = bridge.invoke("com.avast.grpc.jsonbridge.test.TestService/Add", """ { "a": 1, "b": 2} """, Map("My-Header" -> "value"))
+```
 
-case class MyRequest(names: Seq[String])
+### http4s
+```groovy
+compile 'com.avast.grpc:grpc-json-bridge-http4s_2.12:x.x.x'
+```
+```scala
+libraryDependencies += "com.avast.grpc" %% "grpc-json-bridge-http4s" % "x.x.x"
+```
+```scala
+import com.avast.grpc.jsonbridge.GrpcJsonBridge
+import com.avast.grpc.jsonbrige.http4s.{Configuration, Http4s}
+import org.http4s.HttpService
 
-case class MyResponse(results: Map[String, Int])
+val bridge: GrpcJsonBridge[Task] = ???
+val service: HttpService[Task] = Http4s(Configuration.Default)(bridge)
+```
 
-trait MyApi extends GrpcService[Task] {
-  def get(request: MyRequest): Task[Either[Status, MyResponse]]
-}
+### akka-http
+```groovy
+compile 'com.avast.grpc:grpc-json-bridge-akkahttp_2.12:x.x.x'
+```
+```scala
+libraryDependencies += "com.avast.grpc" %% "grpc-json-bridge-akkahttp" % "x.x.x"
+```
 
-val service = new MyApi {
-  override def get(request: MyRequest): Task[Either[Status, MyResponse]] = Task {
-    Right {
-      MyResponse {
-        Map(
-          "name" -> 42
-        )
-      }
-    }
-  }
-}.mappedToService[TestApiServiceImplBase]() // cactus mapping
+```scala
+import com.avast.grpc.jsonbridge.GrpcJsonBridge
+import com.avast.grpc.jsonbridge.akkahttp.{AkkaHttp, Configuration}
+import akka.http.scaladsl.server.Route
 
-val bridge = service.createGrpcJsonBridge[Task, TestApiServiceFutureStub]()
+val bridge: GrpcJsonBridge[Task] = ???
+val route: Route = AkkaHttp(Configuration.Default)(bridge)
 ```
 
-### Calling the bridged service
 
-You can use e.g. cURL command to call the `Get` method
+### Calling the bridged service
+List all available methods:
 ```
-curl -X POST -H "Content-Type: application/json" --data " { \"names\": [\"abc\",\"def\"] } " http://localhost:9999/com.avast.grpc.jsonbridge.test.TestApiServiceGrpc/Get
+> curl -X GET http://localhost:9999/
+
+com.avast.grpc.jsonbridge.test.TestService/Add
 ```
-or get info about exposed service:
+List all methods from particular service:
 ```
-curl -X GET http://localhost:9999/com.avast.grpc.jsonbridge.test.TestApiServiceGrpc
+> curl -X GET http://localhost:9999/com.avast.grpc.jsonbridge.test.TestService
+
+com.avast.grpc.jsonbridge.test.TestService/Add
 ```
-or list available services:
+
+Call a method (please note that `POST` and `application/json` must be always specified):
 ```
-curl -X GET http://localhost:9999/
+> curl -X POST -H "Content-Type: application/json" --data ""{\"a\":1, \"b\": 2 }"" http://localhost:9999/com.avast.grpc.jsonbridge.test.TestService/Add
+
+{"sum":3}
 ```
diff --git a/akka-http/README.md b/akka-http/README.md
diff --git a/akka-http/src/main/scala/com/avast/grpc/jsonbridge/akkahttp/AkkaHttp.scala b/akka-http/src/main/scala/com/avast/grpc/jsonbridge/akkahttp/AkkaHttp.scala
@@ -1,17 +1,15 @@
 package com.avast.grpc.jsonbridge.akkahttp
 
+import cats.effect.implicits._
 import akka.http.scaladsl.model._
 import akka.http.scaladsl.model.headers.`Content-Type`
 import akka.http.scaladsl.server.Directives._
 import akka.http.scaladsl.server.{PathMatcher, Route}
 import cats.data.NonEmptyList
 import cats.effect.Effect
 import com.avast.grpc.jsonbridge.GrpcJsonBridge
-import com.avast.grpc.jsonbridge.GrpcJsonBridge.GrpcHeader
-import io.grpc.BindableService
+import com.avast.grpc.jsonbridge.GrpcJsonBridge.GrpcMethodName
 import io.grpc.Status.Code
-import monix.eval.Task
-import monix.execution.Scheduler
 
 import scala.concurrent.ExecutionContext
 import scala.language.higherKinds
@@ -24,11 +22,7 @@ object AkkaHttp {
     ContentType.WithMissingCharset(MediaType.applicationWithOpenCharset("json"))
   }
 
-  def apply[F[_]: Effect](configuration: Configuration)(bridges: GrpcJsonBridge[F, _ <: BindableService]*)(
-      implicit ec: ExecutionContext): Route = {
-    implicit val sch: Scheduler = Scheduler(ec)
-
-    val bridgesMap = bridges.map(s => (s.serviceName, s): (String, GrpcJsonBridge[F, _])).toMap
+  def apply[F[_]: Effect](configuration: Configuration)(bridge: GrpcJsonBridge[F])(implicit ec: ExecutionContext): Route = {
 
     val pathPattern = configuration.pathPrefix
       .map {
@@ -47,25 +41,19 @@ object AkkaHttp {
         extractRequest { req =>
           req.header[`Content-Type`] match {
             case Some(`JsonContentType`) =>
-              bridgesMap.get(serviceName) match {
-                case Some(service) =>
-                  entity(as[String]) { json =>
-                    val methodCall =
-                      Task.fromEffect {
-                        service.invokeGrpcMethod(methodName, json, mapHeaders(req.headers))
-                      }.runToFuture
-
-                    onComplete(methodCall) {
-                      case Success(Right(r)) =>
-                        respondWithHeader(JsonContentType) {
-                          complete(r)
-                        }
-                      case Success(Left(status)) => complete(mapStatus(status))
-                      case Failure(NonFatal(_)) => complete(StatusCodes.InternalServerError)
+              entity(as[String]) { json =>
+                val methodCall = bridge
+                  .invoke(GrpcMethodName(serviceName, methodName), json, mapHeaders(req.headers))
+                  .toIO
+                  .unsafeToFuture()
+                onComplete(methodCall) {
+                  case Success(Right(r)) =>
+                    respondWithHeader(JsonContentType) {
+                      complete(r)
                     }
-                  }
-
-                case None => complete(StatusCodes.NotFound, s"Service '$serviceName' not found")
+                  case Success(Left(status)) => complete(mapStatus(status))
+                  case Failure(NonFatal(_)) => complete(StatusCodes.InternalServerError)
+                }
               }
 
             case _ =>
@@ -75,25 +63,21 @@ object AkkaHttp {
       }
     } ~ get {
       path(Segment) { serviceName =>
-        bridgesMap.get(serviceName) match {
-          case Some(service) =>
-            complete(service.methodsNames.mkString("\n"))
-
-          case None => complete(StatusCodes.NotFound, s"Service '$serviceName' not found")
+        NonEmptyList.fromList(bridge.methodsNames.filter(_.service == serviceName).toList) match {
+          case None =>
+            complete(StatusCodes.NotFound, s"Service '$serviceName' not found")
+          case Some(methods) =>
+            complete(methods.map(_.fullName).toList.mkString("\n"))
         }
       }
     } ~ get {
       path(PathEnd) {
-        complete(bridgesMap.values.flatMap(s => s.methodsNames).mkString("\n"))
+        complete(bridge.methodsNames.map(_.fullName).mkString("\n"))
       }
     }
   }
 
-  private def mapHeaders(headers: Seq[HttpHeader]): Seq[GrpcHeader] = {
-    headers.map { h =>
-      GrpcHeader(h.name(), h.value())
-    }
-  }
+  private def mapHeaders(headers: Seq[HttpHeader]): Map[String, String] = headers.toList.map(h => (h.name(), h.value())).toMap
 
   private def mapStatus(s: io.grpc.Status): StatusCode = s.getCode match {
     case Code.NOT_FOUND => StatusCodes.NotFound

diff --git a/akka-http/src/test/protobuf/TestServices.proto b/akka-http/src/test/protobuf/TestServices.proto
@@ -0,0 +1,16 @@
+syntax = "proto3";
+
+package com.avast.grpc.jsonbridge.test;
+
+service TestService {
+    rpc Add (AddParams) returns (AddResponse) {}
+}
+
+message AddParams {
+    int32 a = 1;
+    int32 b = 2;
+}
+
+message AddResponse {
+    int32 sum = 1;
+}
diff --git a/akka-http/src/test/protobuf/test_api.proto b/akka-http/src/test/protobuf/test_api.proto