Add gRPC reflection service + documentation on how to use it

Author: vietj

jpms-examples/README.adoc

@@ -119,6 +119,23 @@ Or use the launcher:
 ./target/maven-jlink/default/bin/grpc-server
 ----
 
+You can use https://github.com/fullstorydev/grpcurl[gRPCurl] to interact with the server and its hosted services:
+
+[source,shell]
+----
+> grpcurl -plaintext localhost:8080 list
+grpc.reflection.v1.ServerReflection
+helloworld.Greeter
+
+> grpcurl -plaintext localhost:8080 list helloworld.Greeter
+helloworld.Greeter.SayHello
+
+> grpcurl -plaintext -d '{"name":"Julien"}' localhost:8080 helloworld.Greeter.SayHello
+{
+  "message": "Hello Julien"
+}
+----
+
 == Native transports
 
 A simple link:src/main/java/io/vertx/example/jpms/http2/Server.java[HTTP server] running with Netty native transports kqueue/epoll/io_uring.

jpms-examples/pom.xml

@@ -80,6 +80,10 @@
         </exclusion>
       </exclusions>
     </dependency>
+    <dependency>
+      <groupId>io.vertx</groupId>
+      <artifactId>vertx-grpc-reflection</artifactId>
+    </dependency>
     <dependency>
       <groupId>com.google.protobuf</groupId>
       <artifactId>protobuf-java</artifactId>

jpms-examples/src/main/java/io/vertx/example/jpms/grpc/Server.java

@@ -7,6 +7,7 @@
 import io.vertx.example.jpms.grpc.helloworld.GreeterGrpcService;
 import io.vertx.example.jpms.grpc.helloworld.HelloReply;
 import io.vertx.example.jpms.grpc.helloworld.HelloRequest;
+import io.vertx.grpc.reflection.ReflectionService;
 import io.vertx.grpc.server.GrpcServer;
 
 public class Server extends VerticleBase {
@@ -33,6 +34,9 @@ public Future<HelloReply> sayHello(HelloRequest request) {
     };
     grpcServer.addService(service);
 
+    // Add reflection service
+    grpcServer.addService(ReflectionService.v1());
+
     HttpServer server = vertx
       .createHttpServer(
         new HttpServerOptions()

jpms-examples/src/main/java/module-info.java

@@ -30,6 +30,7 @@
 
   // SQL client template
   requires io.vertx.sql.client.templates;
+  requires io.vertx.grpc.reflection;
 
   exports io.vertx.example.jpms.sqlclient;
   exports io.vertx.example.jpms.sqltemplate;