examples/features/csm_observability: use helloworld client and server…

… instead of echo client and server (grpc#7945)

examples/features/csm_observability/client/main.go

@@ -30,7 +30,7 @@ import (
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials/insecure"
 	xdscreds "google.golang.org/grpc/credentials/xds"
-	"google.golang.org/grpc/examples/features/proto/echo"
+	pb "google.golang.org/grpc/examples/helloworld/helloworld"
 	"google.golang.org/grpc/stats/opentelemetry"
 	"google.golang.org/grpc/stats/opentelemetry/csm"
 	_ "google.golang.org/grpc/xds" // To install the xds resolvers and balancers.
@@ -40,9 +40,12 @@ import (
 	"go.opentelemetry.io/otel/sdk/metric"
 )
 
+const defaultName = "world"
+
 var (
 	target             = flag.String("target", "xds:///helloworld:50051", "the server address to connect to")
 	prometheusEndpoint = flag.String("prometheus_endpoint", ":9464", "the Prometheus exporter endpoint")
+	name               = flag.String("name", defaultName, "Name to greet")
 )
 
 func main() {
@@ -68,15 +71,15 @@ func main() {
 		log.Fatalf("Failed to start NewClient: %v", err)
 	}
 	defer cc.Close()
-	c := echo.NewEchoClient(cc)
+	c := pb.NewGreeterClient(cc)
 
 	// Make an RPC every second. This should trigger telemetry to be emitted from
 	// the client and the server.
 	for {
 		ctx, cancel := context.WithTimeout(context.Background(), time.Second*5)
-		r, err := c.UnaryEcho(ctx, &echo.EchoRequest{Message: "this is examples/opentelemetry"})
+		r, err := c.SayHello(ctx, &pb.HelloRequest{Name: *name})
 		if err != nil {
-			log.Printf("UnaryEcho failed: %v", err)
+			log.Fatalf("Could not greet: %v", err)
 		}
 		fmt.Println(r)
 		time.Sleep(time.Second)

examples/features/csm_observability/server/main.go

@@ -22,15 +22,14 @@ package main
 import (
 	"context"
 	"flag"
-	"fmt"
 	"log"
 	"net"
 	"net/http"
 
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/credentials/insecure"
 	xdscreds "google.golang.org/grpc/credentials/xds"
-	pb "google.golang.org/grpc/examples/features/proto/echo"
+	pb "google.golang.org/grpc/examples/helloworld/helloworld"
 	"google.golang.org/grpc/stats/opentelemetry"
 	"google.golang.org/grpc/stats/opentelemetry/csm"
 	"google.golang.org/grpc/xds"
@@ -45,13 +44,15 @@ var (
 	prometheusEndpoint = flag.String("prometheus_endpoint", ":9464", "the Prometheus exporter endpoint")
 )
 
-type echoServer struct {
-	pb.UnimplementedEchoServer
+// server is used to implement helloworld.GreeterServer.
+type server struct {
+	pb.UnimplementedGreeterServer
 	addr string
 }
 
-func (s *echoServer) UnaryEcho(_ context.Context, req *pb.EchoRequest) (*pb.EchoResponse, error) {
-	return &pb.EchoResponse{Message: fmt.Sprintf("%s (from %s)", req.Message, s.addr)}, nil
+// SayHello implements helloworld.GreeterServer
+func (s *server) SayHello(_ context.Context, in *pb.HelloRequest) (*pb.HelloReply, error) {
+	return &pb.HelloReply{Message: "Hello " + in.GetName()}, nil
 }
 
 func main() {
@@ -80,7 +81,7 @@ func main() {
 	if err != nil {
 		log.Fatalf("Failed to start xDS Server: %v", err)
 	}
-	pb.RegisterEchoServer(s, &echoServer{addr: ":" + *port})
+	pb.RegisterGreeterServer(s, &server{addr: ":" + *port})
 
 	log.Printf("Serving on %s\n", *port)