Ability to customize model name in response metadata (#14)

Add `--model-name` flag in example server to allow customizing response
metadata.

example/go/simple/server/main.go

@@ -6,11 +6,15 @@ import (
 )
 
 var (
-	port = flag.Int("port", 50051, "The server port")
+	port      = flag.Int("port", 50051, "The server port")
+	modelName = flag.String("model-name", "model-a", "Model name to be returned in response metadata")
 )
 
 func main() {
 	flag.Parse()
-	upiServer := UpiServer{}
+	upiServer := UpiServer{
+		modelName: *modelName,
+	}
+
 	upiServer.Run(fmt.Sprintf(":%d", *port))
 }

example/go/simple/server/server.go

@@ -12,17 +12,18 @@ import (
 
 type UpiServer struct {
 	upiv1.UnimplementedUniversalPredictionServiceServer
+	modelName string
 }
 
-func (_ *UpiServer) PredictValues(
+func (s *UpiServer) PredictValues(
 	_ context.Context,
 	req *upiv1.PredictValuesRequest,
 ) (*upiv1.PredictValuesResponse, error) {
 	return &upiv1.PredictValuesResponse{
 		Metadata: &upiv1.ResponseMetadata{
 			Models: []*upiv1.ModelMetadata{
 				{
-					Name:    "Echo Request Table",
+					Name:    s.modelName,
 					Version: "1",
 				},
 			},
@@ -39,7 +40,7 @@ func (us *UpiServer) Run(address string) {
 	s := grpc.NewServer()
 	upiv1.RegisterUniversalPredictionServiceServer(s, us)
 	reflection.Register(s)
-	log.Printf("listening on port %s", address)
+	log.Printf("running model %s on port %s", us.modelName, address)
 	if err := s.Serve(lis); err != nil {
 		log.Fatalf("failed to serve: %v", err)
 	}