Add support for gRPC transcoding

pom.xml

@@ -198,6 +198,7 @@
 
   <modules>
     <module>vertx-grpc-common</module>
+    <module>vertx-grpc-transcoding</module>
     <module>vertx-grpc-server</module>
     <module>vertx-grpc-client</module>
     <module>vertx-grpcio-common</module>
@@ -271,4 +272,4 @@
     </plugins>
   </build>
 
-</project>
+</project>

vertx-grpc-client/src/main/java/io/vertx/grpc/client/impl/GrpcClientResponseImpl.java

@@ -41,7 +41,7 @@ public GrpcClientResponseImpl(ContextInternal context,
                                 long maxMessageSize,
                                 GrpcStatus status,
                                 HttpClientResponse httpResponse, GrpcMessageDecoder<Resp> messageDecoder) {
-    super(context, httpResponse, httpResponse.headers().get("grpc-encoding"), format, maxMessageSize, messageDecoder);
+    super(context, httpResponse, httpResponse.headers().get("grpc-encoding"), format, false, maxMessageSize, messageDecoder);
     this.request = request;
     this.httpResponse = httpResponse;
     this.status = status;

vertx-grpc-common/src/main/java/io/vertx/grpc/common/impl/GrpcReadStreamBase.java

@@ -62,11 +62,13 @@ public Buffer payload() {
   private final GrpcMessageDecoder<T> messageDecoder;
   private final Promise<Void> end;
   private GrpcWriteStreamBase<?, ?> ws;
+  private boolean transcodable;
 
   protected GrpcReadStreamBase(Context context,
                                ReadStream<Buffer> stream,
                                String encoding,
                                WireFormat format,
+                               boolean transcodable,
                                long maxMessageSize,
                                GrpcMessageDecoder<T> messageDecoder) {
     ContextInternal ctx = (ContextInternal) context;
@@ -95,12 +97,18 @@ protected void handleMessage(GrpcMessage msg) {
     };
     this.messageDecoder = messageDecoder;
     this.end = ctx.promise();
+    this.transcodable = transcodable;
   }
 
   public void init(GrpcWriteStreamBase<?, ?> ws) {
     this.ws = ws;
     stream.handler(this);
-    stream.endHandler(v -> queue.write(END_SENTINEL));
+    stream.endHandler(v -> {
+      if (transcodable && last == null) {
+        handle(Buffer.buffer());
+      }
+      queue.write(END_SENTINEL);
+    });
     stream.exceptionHandler(err -> {
       if (err instanceof StreamResetException) {
         StreamResetException reset = (StreamResetException) err;
@@ -267,6 +275,10 @@ public final void tryFail(Throwable err) {
     }
   }
 
+  protected final void cancelTranscodable() {
+    transcodable = false;
+  }
+
   protected final void handleException(Throwable err) {
     tryFail(err);
   }

vertx-grpc-docs/src/main/asciidoc/plugin.adoc

@@ -184,3 +184,59 @@ Vert.x gRPC needs to know to interact with gRPC.
 - the message encoder
 
 They can be used to bind services or interact with a remote server.
+
+=== Generate transcoding definitions
+
+The plugin can also generate transcoding definitions for the gRPC services. For more information see the
+ xref:server.adoc#_grpc_transcoding[Transcoding] section.
+
+==== Generate transcoding definitions
+
+Currently, the plugin supports generating transcoding definitions for the gRPC services via https://github.com/googleapis/api-common-protos/blob/main/google/api/http.proto[http.proto]. This feature is enabled by default.
+
+Example of the gRPC transcoding definition:
+
+[source,proto]
+----
+syntax = "proto3";
+
+import "google/api/http.proto";
+
+service Greeter {
+  rpc SayHello (HelloRequest) returns (HelloReply) {
+    option (google.api.http) = {
+      post: "/v1/hello"
+    };
+  }
+
+  rpc SayHelloAgain (HelloRequest) returns (HelloReply) {
+    option (google.api.http) = {
+      post: "/v1/hello/{name}"
+    };
+  }
+}
+
+message HelloRequest {
+  string name = 1;
+}
+
+message HelloReply {
+  string message = 1;
+}
+
+----
+
+To test if the transcoding is working correctly, you can use the `curl` command:
+
+[source]
+----
+curl -X POST -H "Content-Type: application/json" -d '{"name":"vert.x"}' http://localhost:8080/v1/hello
+----
+
+And for the `SayHelloAgain` method:
+
+[source]
+----
+curl -X POST -H "Content-Type: application/json" http://localhost:8080/v1/hello/vert.x
+----
+

vertx-grpc-docs/src/main/asciidoc/server.adoc

@@ -68,6 +68,90 @@ router.route("/com.mycompany.MyService/*").handler(corsHandler);
 ----
 ====
 
+=== gRPC Transcoding
+
+gRPC transcoding is a feature that enables mapping between HTTP/JSON requests and gRPC services.
+
+==== What is gRPC Transcoding?
+
+gRPC transcoding allows your services to accept both gRPC and HTTP/JSON requests, providing greater flexibility. This feature is particularly useful when:
+
+* You want to expose your gRPC services to clients that don't support gRPC
+* You need to support both traditional REST APIs and gRPC endpoints
+* You want to leverage gRPC's efficiency while maintaining HTTP/JSON compatibility
+
+==== Configuration
+
+==== Enabling Transcoding
+
+By default, gRPC transcoding is disabled in Vert.x. To enable it:
+
+[source,java]
+----
+GrpcServerOptions options = new GrpcServerOptions().setGrpcTranscodingEnabled(true);
+
+GrpcServer server = GrpcServer.server(vertx, options);
+----
+
+==== Creating Bindings
+
+To create HTTP/gRPC bindings:
+
+1. Create a `MethodTranscodingOptions` instance
+2. Configure the binding options
+3. Pass the options when registering the handler
+
+[source,java]
+----
+import io.vertx.grpc.server.GrpcServer;
+import io.vertx.grpc.server.GrpcServerOptions;
+import io.vertx.grpc.transcoding.MethodTranscodingOptions;
+import io.vertx.grpc.common.ServiceMethod;
+import io.vertx.grpc.common.GrpcMessageDecoder;
+import io.vertx.grpc.common.GrpcMessageEncoder;
+import io.vertx.core.http.HttpMethod;
+
+public class GrpcServerExamples {
+
+  // The encoder and decoder for the service method. Must be provided by the user and must be able to decode/encode the from wire format.
+  public static GrpcMessageDecoder<GetUserRequest> DECODER = GrpcMessageDecoder.json(GetUserRequest::newBuilder);
+  public static GrpcMessageEncoder<GetUserResponse> ENCODER = GrpcMessageEncoder.json();
+
+  public GrpcServer createTranscodingServer() {
+    // Create a new gRPC server with transcoding enabled
+    GrpcServer server = GrpcServer.server(vertx, new GrpcServerOptions().setGrpcTranscodingEnabled(true));
+
+    // Define the service method
+    ServiceMethod<GetUserRequest, GetUserResponse> getUser = ServiceMethod.server("UserService", "GetUser", ENCODER, DECODER);
+
+    // Define the transcoding options
+    MethodTranscodingOptions transcodingOptions = new MethodTranscodingOptions(null, HttpMethod.GET, "/v1/users/{id}", "*", null, null);
+
+    // Register the handler with transcoding options
+    server.callHandlerWithTranscoding(
+        getUser,
+        request -> {
+            // Handle the request
+        },
+        transcodingOptions
+    );
+
+    return server;
+  }
+}
+----
+
+==== Testing Transcoding
+
+To test gRPC transcoding, you can use a tool like `curl` to send HTTP requests to your gRPC service.
+
+For example, to send a `GET` request to the `/v1/users/123` endpoint:
+
+[source]
+----
+curl -X GET http://localhost:8080/v1/users/123
+----
+
 === Server request/response API
 
 The gRPC request/response server API provides an alternative way to interact with a client without the need of extending

vertx-grpc-docs/src/main/java/examples/VertxGreeterGrpcServer.java

@@ -3,6 +3,7 @@
 import io.vertx.core.Future;
 import io.vertx.core.Promise;
 import io.vertx.core.Handler;
+import io.vertx.core.http.HttpMethod;
 import io.vertx.core.http.HttpServerRequest;
 import io.vertx.core.streams.ReadStream;
 import io.vertx.core.streams.WriteStream;
@@ -13,6 +14,7 @@
 import io.vertx.grpc.common.GrpcWriteStream;
 import io.vertx.grpc.common.GrpcMessageDecoder;
 import io.vertx.grpc.common.GrpcMessageEncoder;
+import io.vertx.grpc.transcoding.MethodTranscodingOptions;
 import io.vertx.grpc.server.GrpcServerResponse;
 import io.vertx.grpc.server.GrpcServer;
 
@@ -32,6 +34,7 @@ public class VertxGreeterGrpcServer  {
     GrpcMessageEncoder.json(),
     GrpcMessageDecoder.json(() -> examples.HelloRequest.newBuilder()));
 
+
   public static class GreeterApi {
 
     public Future<examples.HelloReply> sayHello(examples.HelloRequest request) {
@@ -75,6 +78,7 @@ public GreeterApi bind_sayHello(GrpcServer server, io.vertx.grpc.common.WireForm
       return this;
     }
 
+
     public final GreeterApi bindAll(GrpcServer server) {
       bind_sayHello(server);
       return this;
@@ -84,5 +88,13 @@ public final GreeterApi bindAll(GrpcServer server, io.vertx.grpc.common.WireForm
       bind_sayHello(server, format);
       return this;
     }
+
+    public final GreeterApi bindAllWithTranscoding(GrpcServer server) {
+      return this;
+    }
+
+    public final GreeterApi bindAllWithTranscoding(GrpcServer server, io.vertx.grpc.common.WireFormat format) {
+      return this;
+    }
   }
 }

vertx-grpc-docs/src/main/java/examples/VertxStreamingGrpcServer.java

@@ -3,6 +3,7 @@
 import io.vertx.core.Future;
 import io.vertx.core.Promise;
 import io.vertx.core.Handler;
+import io.vertx.core.http.HttpMethod;
 import io.vertx.core.http.HttpServerRequest;
 import io.vertx.core.streams.ReadStream;
 import io.vertx.core.streams.WriteStream;
@@ -13,6 +14,7 @@
 import io.vertx.grpc.common.GrpcWriteStream;
 import io.vertx.grpc.common.GrpcMessageDecoder;
 import io.vertx.grpc.common.GrpcMessageEncoder;
+import io.vertx.grpc.transcoding.MethodTranscodingOptions;
 import io.vertx.grpc.server.GrpcServerResponse;
 import io.vertx.grpc.server.GrpcServer;
 
@@ -52,6 +54,7 @@ public class VertxStreamingGrpcServer  {
     GrpcMessageEncoder.json(),
     GrpcMessageDecoder.json(() -> examples.Item.newBuilder()));
 
+
   public static class StreamingApi {
 
     public ReadStream<examples.Item> source(examples.Empty request) {
@@ -163,6 +166,7 @@ public final StreamingApi bind_pipe(GrpcServer server, io.vertx.grpc.common.Wire
       return this;
     }
 
+
     public final StreamingApi bindAll(GrpcServer server) {
       bind_source(server);
       bind_sink(server);
@@ -176,5 +180,13 @@ public final StreamingApi bindAll(GrpcServer server, io.vertx.grpc.common.WireFo
       bind_pipe(server, format);
       return this;
     }
+
+    public final StreamingApi bindAllWithTranscoding(GrpcServer server) {
+      return this;
+    }
+
+    public final StreamingApi bindAllWithTranscoding(GrpcServer server, io.vertx.grpc.common.WireFormat format) {
+      return this;
+    }
   }
 }