add server streaming example

cmd/client/main.go

@@ -27,6 +27,7 @@ const defaultAddress = "localhost:50001"
 
 const (
 	exampleUnary         = "unary"
+	exampleServer        = "server"
 	exampleClient        = "client"
 	exampleBidirectional = "bidirectional"
 )
@@ -63,6 +64,8 @@ func main() {
 	switch example {
 	case exampleUnary:
 		sayHello(ctx, client, logger)
+	case exampleServer:
+		sayHelloServerStream(ctx, client, logger)
 	case exampleClient:
 		sayHelloClientStream(ctx, client, logger)
 	case exampleBidirectional:
@@ -78,7 +81,7 @@ func parseExample() string {
 		&example,
 		"example",
 		exampleUnary,
-		fmt.Sprintf("%s, %s or %s (default: %s)", exampleUnary, exampleClient, exampleBidirectional, exampleUnary),
+		fmt.Sprintf("%s, %s, %s or %s (default: %s)", exampleUnary, exampleServer, exampleClient, exampleBidirectional, exampleUnary),
 	)
 	flag.Parse()
 	return example
@@ -121,13 +124,47 @@ func newTransportCredentials() (credentials.TransportCredentials, error) {
 }
 
 func sayHello(ctx context.Context, client proto.GreeterClient, logger *zap.Logger) {
-	reply, err := client.SayHello(ctx, &proto.HelloRequest{Name: uuid.NewString()})
+	name := uuid.NewString()
+	logger.Info("sending request", zap.String("name", name))
+	reply, err := client.SayHello(ctx, &proto.HelloRequest{Name: name})
 	if err != nil {
 		logger.Fatal("something went wrong while calling SayHello", zap.Error(err))
 	}
 	logger.Info("reply received", zap.String("message", reply.GetMessage()))
 }
 
+const (
+	namesLen = 20
+)
+
+func sayHelloServerStream(ctx context.Context, client proto.GreeterClient, logger *zap.Logger) {
+	names := make([]string, namesLen)
+	for i := range names {
+		names[i] = uuid.NewString()
+	}
+
+	logger.Info("sending request", zap.Strings("names", names))
+	streamClient, err := client.SayHelloServerStream(ctx, &proto.MultiHelloRequest{Names: names})
+	if err != nil {
+		logger.Fatal("something went wrong while calling SayHelloServerStream", zap.Error(err))
+	}
+	defer func() {
+		_ = streamClient.CloseSend()
+	}()
+
+	for {
+		reply, err := streamClient.Recv()
+		if errors.Is(err, io.EOF) {
+			return
+		}
+		if err != nil {
+			logger.Fatal("couldn't receive reply", zap.Error(err))
+		}
+
+		logger.Info("reply received", zap.String("message", reply.GetMessage()))
+	}
+}
+
 func sayHelloClientStream(ctx context.Context, client proto.GreeterClient, logger *zap.Logger) {
 	// ctx is used later to close the stream client
 	//nolint:contextcheck
@@ -140,7 +177,7 @@ func sayHelloClientStream(ctx context.Context, client proto.GreeterClient, logge
 		if err != nil {
 			logger.Fatal("couldn't receive reply", zap.Error(err))
 		}
-		logger.Info("reply received", zap.String("message", reply.GetMessage()))
+		logger.Info("reply received", zap.Strings("messages", reply.GetMessages()))
 	}()
 
 	ticker := time.NewTicker(time.Second)

cmd/server/main.go

@@ -11,7 +11,6 @@ import (
 	"net"
 	"os"
 	"os/signal"
-	"strings"
 	"syscall"
 
 	"gitea.dwysokinski.me/Kichiyaki/grpc-g2a/cmd/internal"
@@ -157,23 +156,31 @@ func (g *greeterServer) SayHello(_ context.Context, r *proto.HelloRequest) (*pro
 	}, nil
 }
 
+func (g *greeterServer) SayHelloServerStream(r *proto.MultiHelloRequest, stream proto.Greeter_SayHelloServerStreamServer) error {
+	for _, n := range r.GetNames() {
+		if err := stream.Send(&proto.HelloReply{
+			Message: buildHelloMsg(n),
+		}); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
 func (g *greeterServer) SayHelloClientStream(stream proto.Greeter_SayHelloClientStreamServer) error {
-	var b strings.Builder
+	var messages []string
 	for {
 		r, err := stream.Recv()
 		if errors.Is(err, io.EOF) {
-			return stream.SendAndClose(&proto.HelloReply{
-				Message: b.String(),
+			return stream.SendAndClose(&proto.MultiHelloReply{
+				Messages: messages,
 			})
 		}
 		if err != nil {
 			return fmt.Errorf("stream returned error: %w", err)
 		}
 
-		if b.Len() > 0 {
-			b.WriteString(" ")
-		}
-		b.WriteString(buildHelloMsg(r.GetName()))
+		messages = append(messages, buildHelloMsg(r.GetName()))
 	}
 }
 

proto/hello_world.proto

@@ -4,7 +4,8 @@ option go_package = "gitea.dwysokinski.me/Kichiyaki/grpc-g2a/proto";
 
 service Greeter {
   rpc SayHello (HelloRequest) returns (HelloReply) {}
-  rpc SayHelloClientStream (stream HelloRequest) returns (HelloReply) {}
+  rpc SayHelloClientStream (stream HelloRequest) returns (MultiHelloReply) {}
+  rpc SayHelloServerStream (MultiHelloRequest) returns (stream HelloReply) {}
   rpc SayHelloBidirectionalStream (stream HelloRequest) returns (stream HelloReply) {}
 }
 
@@ -12,6 +13,14 @@ message HelloRequest {
   string name = 1;
 }
 
+message MultiHelloRequest {
+  repeated string names = 1;
+}
+
 message HelloReply {
   string message = 1;
 }
+
+message MultiHelloReply {
+  repeated string messages = 1;
+}