This document discusses building microservices with gRPC in Golang. It provides an overview of gRPC, including that it is an open-source, high performance RPC framework created by Google. It supports features like bi-directional streaming over HTTP/2 and works across multiple languages and platforms. The document also provides an example of defining a simple gRPC service in Protobuf IDL and generating and implementing the client and server code in Go.

1. Build microserviceBuild microservice
with gRPC in Golangwith gRPC in Golang
David Chou

2. We are UmboWe are Umbo
Computer VisionComputer Vision
We buildWe build
autonomous videoautonomous video
security systemsecurity system

3. CyberlinkCyberlink
TrendMicroTrendMicro
Umbo CVUmbo CV
Google I/O ExtendGoogle I/O Extend
Golang TaipeiGolang Taipei

4. A high performance, open source, general purpose
standards-based, feature-rich RPC framework.

5. O(10^10) RPCs per second at Google

6. gRPC: MotivationgRPC: Motivation
Google has its internal RPC called Stubby
All applications and systems built using RPCs
Over 10^10 RPCs per second
Tightly couple with internal infrastructure
Not suitable for open source community

7. gRPC: StatusgRPC: Status
A high performance, universal RPC framework
Google open sourced it in Feb 2015
Being 1.0 in Aug 2016
Latest version: v1.3.2
Already been adpoted in
CoreOS, Netflix, Square, Cisco, Juniper

8. gRPC: FeaturesgRPC: Features
Bi-directional streaming over HTTP/2
Support multi-language, multi-platform
Simple service definition framework

9. Bi-directional streaming over HTTP/2Bi-directional streaming over HTTP/2
Single TCP connection for each client-server pair
Support bi-directional streaming

10. Support multi-language,Support multi-language,
multi-platformmulti-platform
Use protoc as the code generator
Native implementations in C/C++, Java, and Go
C stack wrapped by C#, Node, ObjC, Python, Ruby, PHP
Platforms supported: Linux, MacOS, Windows, Android, iOS
Currently, no browser side support. #8682
gRPC gateway
gRPC-web

11. Simple service definition frameworkSimple service definition framework
Use Protocol Buffer IDL
Service definition
Generate server and client stub code
Message definition
Binary format
Much better performace than json

12. syntax = "proto3";
package pb;
message EchoMessage {
string msg = 1;
}
service EchoService {
rpc Echo(EchoMessage) returns (EchoMessage);
}
Protobuf IDL: EchoServiceProtobuf IDL: EchoService

13. BenchmarkToJSON_1000_Director-2 500 2512808 ns/op 560427 B/op 9682 allocs/op
BenchmarkToPB_1000_Director-2 2000 1338410 ns/op 196743 B/op 3052 allocs/op
BenchmarkToJSONUnmarshal_1000_Director-4 1000 1279297 ns/op 403746 B/op 5144 allocs/op
BenchmarkToPBUnmarshal_1000_Director-4 3000 489585 ns/op 202256 B/op 5522 allocs/op
Json vs Protobuf performanceJson vs Protobuf performance
Ref: Dgraph: JSON vs. Binary clients
Marshalling: 2x faster, 65% less memory
Unmarshalling: 2.6x faster, 50% less memory

15. Example: DemoServiceExample: DemoService

16. gRPC Service DefinitiongRPC Service Definition
message Demo {
string value = 1;
}
service DemoService {
rpc SimpleRPC(Demo) returns (Demo);
rpc ServerStream(Demo) returns (stream Demo);
rpc ClientStream(stream Demo) returns (Demo);
rpc Bidirectional(stream Demo) returns (stream Demo);
}

17. gRPC Service DefinitiongRPC Service Definition
gRPC supprots 4 kinds of service methods
Unary RPC
Server streaming RPC
Client streaming RPC
Bidirectional RPC

18. Generate client and server codeGenerate client and server code
Run protoc to generate client/server interfaces
$ protoc --go_out=plugins=grpc:. demo.proto
protoc will generate demo.pb.go
Install relevant tools

19. demo.pb.godemo.pb.go
type Demo struct {
Value string `protobuf:"bytes,1,opt,name=value" json:"value,omitempty"`
}
// Client API for DemoService service
type DemoServiceClient interface {
SimpleRPC(ctx context.Context, in *Demo, opts ...grpc.CallOption) (*Demo, error)
ServerStream(ctx context.Context, in *Demo, opts ...grpc.CallOption) (DemoService_ServerStreamClient,
ClientStream(ctx context.Context, opts ...grpc.CallOption) (DemoService_ClientStreamClient, error)
Bidirectional(ctx context.Context, opts ...grpc.CallOption) (DemoService_BidirectionalClient, error)
}
// Implementation of DemoService client
type demoServiceClient struct {
cc *grpc.ClientConn
}
func NewDemoServiceClient(cc *grpc.ClientConn) DemoServiceClient {
...
}
// Server API for DemoService service
type DemoServiceServer interface {
SimpleRPC(context.Context, *Demo) (*Demo, error)
ServerStream(*Demo, DemoService_ServerStreamServer) error
ClientStream(DemoService_ClientStreamServer) error
Bidirectional(DemoService_BidirectionalServer) error
}

20. Go ServerGo Server
type server struct{}
func (this *server) SimpleRPC(c context.Context, msg *Demo) (*Demo, error) {
msg.Value = "Hello" + msg.Value
return msg, nil
}
func (this *server) ServerStream(msg *Demo, stream DemoService_ServerStreamServer) error {
for i := 0; i < 10; i++ {
err := stream.Send(&Demo{value: "Hello"})
if err != nil {
fmt.Printf("err: %sn", err.Error())
}
time.Sleep(100 * time.Millisecond)
}
return nil
}
func main() {
lis, err := net.Listen("tcp", "localhost:12345")
if err != nil {
log.Fatalf("Failed to listen: %v", err)
}
grpcServer := grpc.NewServer()
RegisterDemoServiceServer(grpcServer, &server{})
grpcServer.Serve(lis)
}

21. Go Client: SimpleRPCGo Client: SimpleRPC
func main() {
grpcAddr := "localhost:12345"
conn, err := grpc.Dial(grpcAddr)
if err != nil {
log.Fatalf("Dial(%s) = %v", grpcAddr, err)
}
defer conn.Close()
client := NewDemoServiceClient(conn)
msg := &Demo{value: "World"}
reply, err := client.SimpleRPC(context.Background(), msg)
if err != nil {
log.Fatalf("SimpleRPC(%#v) failed with %v", msg, err)
}
println("received message " + reply.Value)
}

22. Go Client: ServerStreamGo Client: ServerStream
func main() {
grpcAddr := "localhost:12345"
conn, err := grpc.Dial(grpcAddr)
if err != nil {
log.Fatalf("Dial(%s) = %v", grpcAddr, err)
}
defer conn.Close()
client := NewDemoServiceClient(conn)
stream, err := client.ServerStream(context.TODO(), &Demo{
Value: "Hello",
})
for {
msg, err := stream.Recv()
if err == io.EOF {
break
}
fmt.Printf("%+vn", msg)
}
}

23. Let's go deeperLet's go deeper

24. gRPC build-in authenticationgRPC build-in authentication
Two types of Credentials objects
Channel credentials
Call credentials

25. Channel credentialsChannel credentials
Credentials are attached to a Channel
Ex: SSL credentials
tls := credentials.NewClientTLSFromCert(nil, "")
conn, err := grpc.Dial(serverAddr, grpc.WithTransportCredentials(tls))
creds, err := credentials.NewServerTLSFromFile(certFile, keyFile)
server := grpc.NewServer(grpc.Creds(creds))
server.Serve()
TLS on server side
TLS on client side

26. Call credentialsCall credentials
Credentials are attached to each RPC call
Token based authentication, ex: OAuth, JWT

27. func unaryInterceptor(ctx context.Context, req interface{}
if err := authorize(ctx); err != nil {
return err
}
return handler(ctx, req)
}
func authorize(ctx context.Context) error {
if md, ok := metadata.FromContext(ctx); ok {
if checkJWT(md["jwt"][0]) {
return nil
}
return AccessDeniedErr
}
return EmptyMetadataErr
}
grpc.NewServer(grpc.UnaryInterceptor(unaryInterceptor))
TLS on server side
type JWTCreds struct {
Token string
}
func (c *JWTCreds) GetRequestMetadata(context.Context, ..
return map[string]string{
"jwt": c.Token,
}, nil
}
grpc.Dial(target, grpc.WithPerRPCCredentials(&JWTCreds{
Token: "test-jwt-token",
}))
TLS on client side
Ref: grpc-go #106

28. gRPC load balancegRPC load balance
Approaches to Load Balancing
Server-side LB
Client-side LB

31. Load Balancing in gRPCLoad Balancing in gRPC
#gRPC load balancing proposal

32. Any Question?Any Question?