, LINE
 
gRPC JJUG CCC 2019 Spring #ccc_a1 1 

• LINE 

  
 • (Maeda Kentaro) • Twitter: kencharos JJUG CCC 2019 Spring #ccc_a1 2 

Agenda • gRPC
 • Protocol Buffers  • gRPC Java  • gRPC  JJUG CCC 2019 Spring #ccc_a1 3 

 &"  l 
 !% gRPC '  #($ ) 4 JJUG CCC 2019 Spring #ccc_a1 

Agenda • gRPC
 • Protocol Buffres  • gRPC Java  • gRPC  JJUG CCC 2019 Spring #ccc_a1 5 

0 / I ) / / ) / / F P l oil l epC ) rc l 2 / R P N F nm l ( F 1 0 / C l 0 /t u g bj da F 6 0 ) CG https://grpc.io/ JJUG CCC 2019 Spring #ccc_a1 

l e > p • - I >c A B T • > tPT P c DH o B >gp I • D >c DL I BD C B C l u • + ( 2 s • L / )r l f l > RAL g I DH T 7 4/ ) JJUG CCC 2019 Spring #ccc_a1 

l ) 1 / 2 • ( m UT RU C C l S t C • a • UTe a • L P l n H i • s C L P c P C i 8 JJUG CCC 2019 Spring #ccc_a1 

) PR o i hli fi l ) I R nH SR l o rLR+( e g e l +( H tuwJ a yG ld i • ,1B1# ) # # # D# # # D # 0C ### l ptuwJ i i fi • s c b LR v 9 JJUG CCC 2019 Spring #ccc_a1 

l I L P C D l I R B 10 proto file message (
 ) service (PRC ) protoc Protocol Buffers gRPC plugin 
 Message  Service  Protocol Buffers   gRPC   JJUG CCC 2019 Spring #ccc_a1 

l e / UWT N l . gab UWT p tP • P ( . / P l / A H NPL T A J l L . / P . UWT w E wEL . / . r LC • A . R O SI • . . / )/ + L o T 11 . / ( / P n JJUG CCC 2019 Spring #ccc_a1 

Agenda • gRPC
 • Protocol Buffers  • gRPC Java  • gRPC  JJUG CCC 2019 Spring #ccc_a1 12 

l proto"&A5
!<;3CLI & • https://github.com/protocolbuffers/protobuf l #%'8F$,B • gRPC
Open API
12/B?+ E l gRPC Java :4
protoc  gradle/maven 0D.=@ 6 
)7 9 • (*:4>=6 • gRPC-web, gRPC-gateway, doc-gen  Java(-#%' 6:4 • Go, C++  C12!<; :4 13 protoc 
 JJUG CCC 2019 Spring #ccc_a1 

l gRPC 
 version 3  l   message, RPC  service  ! • package
Option
import  "    ! 14 proto 
 syntax = "proto3"; package my.rpc; option java_package = "my.rpc"; message SomeMessage{///} service SomeService{///} JJUG CCC 2019 Spring #ccc_a1 

l Java  1!'  message 0 8.
5%*  l Java1!3249* 15 message
 message Person { int32 id = 1; string name = 2; Gender gender = 3; enum Gender { man = 0; woman = 1; } } 
-/ int32, int64, uint32, uint64,double, , bool 6(: string : bytes :"$ enum #7 repeated $.  )+ map message 1!&message JJUG CCC 2019 Spring #ccc_a1 

l Protocol Buffers ('.I7+/&H8?K = L9 • +/&,#*0 .-!/$ .-! 36  • +/&H8:NM  l EA Person id150DG  , 08 96 01 (%P 16 
  0000 0100 212)#%6@O5@K
<+/&H8 = 1 1001 0110 0000 0001 ;C1)#%$"QF>  21(%J
4B  000 0001 ++ 001 0110 -> 10010110 -> 128 + 16 + 4 + 2 -> 150 JJUG CCC 2019 Spring #ccc_a1 

l proto #%C?,#%!A2 D8   • " $&' proto <;!:3 0G   • message /=B.#%!A2>)1
4F E1 • #%!A26E-79 reserved  17 
  //version1 message Something { int32 id = 1; string name = 2; } //version2 *@+ message Something { int32 id = 1; string name = 2[deprecated=true]; string fullName = 3; } //version3 (15 message Something { int32 id = 1; reserved 2; string fullName = 3; } JJUG CCC 2019 Spring #ccc_a1 

l Java  service & RPC ' / ,$
"message
-%message ( l *"' / stream "-% ). 
RPC 40 +0 l !# 18 service 
service GreetingService { rpc Hello(Person) returns (Greeting) rpc HelloStream(stream Person) returns (stream Greeting) } JJUG CCC 2019 Spring #ccc_a1 

Agenda • gRPC
 • Protocol Buffers  • gRPC Java  • gRPC  JJUG CCC 2019 Spring #ccc_a1 19 

20  proto 
 JJUG CCC 2019 Spring #ccc_a1 syntax = "proto3"; // The fizbuz service definition. service FizBuzService { rpc FizBuzOne (InputNumber) returns (FizBuzAnswer) {} rpc FizBuzRange (FromTo) returns (stream FizBuzAnswer) {} rpc FizBuzBatch (stream InputNumber) returns (FizBuzList) {} rpc FizBuzMany (stream InputNumber) returns (stream FizBuzAnswer) {} } message InputNumber { int32 num = 1; } message FizBuzAnswer { string answer = 1; } //
 

21 Protocol Buffers
 JJUG CCC 2019 Spring #ccc_a1 l maven/gradle Protocol Buffers   gRPC plugin $ • src/main/proto  proto" apply plugin: 'com.google.protobuf' apply plugin: "idea" protobuf { protoc { artifact = "com.google.protobuf:protoc: 3.6.1 " } plugins { grpc { // grpc plugin # artifact = "io.grpc:protoc-gen-grpc-java:1.18.1" } } generateProtoTasks { //plugin "
all()*.plugins { grpc {} // grpc plugin !$ } } ProtocolBuffrers   gRPC plugin#  gRPC plugin!$ 

22
 JJUG CCC 2019 Spring #ccc_a1 l  build/generated   l gradle    
 • https://github.com/google/pr otobuf-gradle-plugin 

23 gRPC Java
 JJUG CCC 2019 Spring #ccc_a1 
 Stub RPCproto'5 .- gRPC Server Stub /12  gRPC Sevice gRPC Server & RPCProto '5.-%
!3 Server 4: Channel  gRPC Server /1 7,RPC$) #8  message PRC*96 Stub-gRPC Service " 0(+ Protocol Buferes message 

24 gRPC Java 
 JJUG CCC 2019 Spring #ccc_a1    Stub Stub gRPC Server gRPC Service gRPC Service Channel RPC RPC message message l Proto 
 

25 

:gRPC Server JJUG CCC 2019 Spring #ccc_a1 l ServerBuilder  addService  GrpcService&+ ' • !$ Netty
TLS #%  NettryServiceBuilder () • RPC"* Netty  NIO ! public static void main(String[] args)throws Exception{ var builder = (NettyServerBuilder)ServerBuilder .forPort(6565) .addService(new FizBuzBasicGrpcService()); // builder.sslContext(...); var server = builder.build(); server.start(); server.awaitTermination(); } 

26 
:Channel JJUG CCC 2019 Spring #ccc_a1 l ManagedChannel  * 9 l -  5)8< RPC#3
.' 2!1 * ; l gRPC  TLS 4%
, TLS +/  &
usePlaintext :"0$76 .( ManagedChannel createChannel() { return ManagedChannelBuilder.forAddress("localhost", 6565) .usePlaintext() .build(); } 

27 
:Stub JJUG CCC 2019 Spring #ccc_a1 l 1;65 ServiceGrpc (33C $65' !"
 Channel : 65  l 0B-=RPC%*(&?@, • 942/+ BlockingStub  FutureStub0 var blockStub = FizBuzServiceGrpc.newBlockingStub(channel); var futureStub = FizBuzServiceGrpc.newFutureStub(channel); var stub = FizBuzServiceGrpc.newStub(channel); Stub 
RPC  BlockingStub unary, server side stream <.('!A8) FutureStub unary ><. (Future A8) Stub 7 StreamObsever)#! 

28 RPC
 JJUG CCC 2019 Spring #ccc_a1 l RPC6# .;3 stream RPC(= $ l  !RPC4
:.87" 0),   • 5+ Unary& 1 • 87"*<9-'/:% RPC RPC
 Unary RPC rpc Hello(In) returns (Out) 121 Server Streaming RPC rpc Hello(In) returns (stream Out) 121 Client Streaming RPC rpc Hello(stream In) returns (Out) 121 Bidirectional Streaming RPC rpc Hello(stream In) returns (stream Out) 121 

29 
 RPC  JJUG CCC 2019 Spring #ccc_a1 l %)-,/!1TRPCZI6(&NCH : • (&NCH
(&NHD (=RPC Da)L[?RP@KY^ • 4TWJRH>`3 XU8E_ ".*' Y^ l gRPC Java StreamObserver +$ )] F9@KA; • Stub, #*b[RPCQ5SG  • RPC%&+Bc gRPC E_2d 
AM7O • <= A;V\0 

30 StreamObserver 
 JJUG CCC 2019 Spring #ccc_a1 l 
2StreamObserver  Stub gRPC Service RPC(Unary) Stream Observer Stream Observer message message onNext onCompleted onNext onCompleted 

31 StreamObserver
 JJUG CCC 2019 Spring #ccc_a1 l onNext : 
 .+0/(+!/ • $2 *# -& 
.+ • -& *# $2 
(+ 
 • 
)3 1,%" l onCompleted : 
.+ 4 0/!/ • %" RPC '5 l onError : 
!/ 

32 Unary RPC JJUG CCC 2019 Spring #ccc_a1 l &*"! +; 
# ! +: • 84'")%*
/0 1 .2 • &*"7 StreamObserver gRPC!$("36 9- 36,8 Stub gRPC Service RPC5< Stream Observer Stream Observer message message onNext onCompleted onNext onCompleted 

33 Unary RPC
 JJUG CCC 2019 Spring #ccc_a1 // Client InputNumber input = InputNumber.newBuilder().setNum(1).build(); FizBuzAnswer a1 = blockStub.fizBuzOne(input); System.out.println(a1.getAnswer()); // Server Unary @Override public void fizBuzOne(InputNumber request, StreamObserver responseObserver) { String answer = calc.calc(request.getNum()); // send response to client responseObserver.onNext(FizBuzAnswer.newBuilder().setAnswer(answer).build()); // send RPC finish to client responseObserver.onCompleted(); } 

34 ()message  POJO
JJUG CCC 2019 Spring #ccc_a1 l Protocol Buffers  message  67(immutable) getter 
setter ,  l message (4 builder +9  l message  AbstractMessage %&-
"! /"!
%/8*.  , var num = InputNumber.newBuilder() // builder )1 .setNum(10) // #25 .build(); // message (4 var num2 = InputNumber.newBuilder(num) // $3 builder )1 .setNum(100) // '0 .build(); // (4 

35 Server Streaming RPC JJUG CCC 2019 Spring #ccc_a1 l  * 
(& ) • Unary  onNext(&!# • BlockingStub  Iterator " $' Stub gRPC Service RPC%+ Stream Observer Stream Observer message message onNext onCompleted onNext onCompleted message onNext 

Iterator a2 = blockStub.fizBuzRange(FromTo.newBuilder().setFrom(2).setTo(20).build()); while (a2.hasNext()) { System.out.println(a2.next().getAnswer()); } // server side stream @Override public void fizBuzRange(FromTo request, StreamObserver observer) { var anserList = IntStream.range(request.getFrom(), request.getTo()) .boxed().map(i -> calc.calc(i)).collect(Collectors.toList()); // send stream data for (String answer : anserList) { observer.onNext(FizBuzAnswer.newBuilder().setAnswer(answer).build()); } observer.onCompleted(); } 36 Server Streaming RPC
 JJUG CCC 2019 Spring #ccc_a1 

37 Client Streaming RPC JJUG CCC 2019 Spring #ccc_a1 l  ($&
&"   ) • 
!%' Stub gRPC Service RPC#* Stream Observer Stream Observer message onNext onCompleted onCompleted message onNext message onNext 

38 Client Streaming RPC
(Stub) JJUG CCC 2019 Spring #ccc_a1 // 32"(5#- Latch CountDownLatch waitFinish = new CountDownLatch(1); // RPC %&1 StreamObserver +/ var requestSender = stub.fizBuzBatch(new StreamObserver() { @Override public void onNext(FizBuzList value) { // 1
Client Streaming 0 System.out.println(“received answers” + value); } @Override public void onCompleted() { waitFinish.countDown(); // !6 '6 } @Override public void onError(Throwable t) {waitFinish.countDown();} }); // ,)4*$ requestSender.onNext(InputNumber.newBuilder().setNum(11).build()); requestSender.onNext(InputNumber.newBuilder().setNum(10).build()); requestSender.onNext(InputNumber.newBuilder().setNum(27).build()); // ,)'6. requestSender.onCompleted(); // RPC'6 waitFinish.await(); ,)  1 

39 Client Streaming RPC
(Server) JJUG CCC 2019 Spring #ccc_a1 @Override public StreamObserver fizBuzBatch(StreamObserver responseObserver) { //   !
$ var inputNumbers = new ArrayList(); //   

 " return new StreamObserver() { @Override public void onNext(InputNumber value) { // 
$  inputNumbers.add(value); } @Override public void onCompleted() { // StubonComplete# var answers = inputNumbers.stream().map(i -> i.getNum()) .map(i -> calc.calc(i)).collect(toList()); responseObserver.onNext(FizBuzList.newBuilder().addAllAnswer(answers).build()); responseObserver.onCompleted(); } @Override public void onError(Throwable t) {t.printStackTrace();} }; } 
 % ! 

40 Bidirectional Streaming RPC JJUG CCC 2019 Spring #ccc_a1 l "# !:5604  • Ping-Pong $8$%9
)*2/ 6+  •  onCompleted (RPC'7 3.& -,; Stub gRPC Service RPC1< Stream Observer Stream Observer message onNext onCompleted onCompleted message onNext message onNext message onNext 

var bdRequestSender = stub.fizBuzMany(new StreamObserver() { @Override public void onNext(FizBuzAnswer value) { System.out.println("receive " + value.getAnswer()); } @Override public void onCompleted() { waitFinish.countDown(); } @Override public void onError(Throwable t) { waitFinish.countDown(); } }); // receive server data each onNext. bdRequestSender.onNext(InputNumber.newBuilder().setNum(3).build()); bdRequestSender.onNext(InputNumber.newBuilder().setNum(1).build()); bdRequestSender.onNext(InputNumber.newBuilder().setNum(80).build()); // send finish to server. bdRequestSender.onCompleted(); waitFinish.countDown(); 41 Bidirectional Streaming RPC
(Stub) JJUG CCC 2019 Spring #ccc_a1 
  
 

@Override public StreamObserver fizBuzMany(StreamObserver responseObserver) { return new StreamObserver() { @Override public void onNext(InputNumber value) { // one by one data send. var answer = calc.calc(value.getNum()); responseObserver.onNext( FizBuzAnswer.newBuilder().setAnswer(answer).build()); } @Override public void onCompleted() { responseObserver.onCompleted(); } @Override public void onError(Throwable t) { t.printStackTrace(); } }; } 42 Bidirectional Streaming RPC
(Server) JJUG CCC 2019 Spring #ccc_a1 
   

43  gRPC 
 JJUG CCC 2019 Spring #ccc_a1 l API ,<9Request-Response  Unary ,< • 04 *7 l Streaming API=- 
 .:  • 
#
6?
;)13 • %'!6?
;)53? • #2> /+2>$"&'? l Streaming 2> deadline 8( 

44 deadline JJUG CCC 2019 Spring #ccc_a1 l
 l Stub -+1deadline 6 2* • RPC'5,." 0&!'5$(% 0 +1 l Server -   deadline)#/   // deadline  100 4+1 var blockStub = FizBuzServiceGrpc.newBlockingStub(channel) .withDeadlineAfter(100, TimeUnit.MICROSECONDS); // Server - deadline 31 if(Context.current().getDeadline().isExpired()) { responseObserver.onError(new RuntimeException()); } 

45 ( )Stream 
 JJUG CCC 2019 Spring #ccc_a1 l Reactive-gRPC(https://github.com/salesforce/reactive-grpc) • Salesforce gRPC4H
RxJava/Reactor ; Stub, Service $)BA  • StreamObserver 2O
LF6@$ )BA
'%( 
D ." ' + -!+-.78  • 1K
."' +N3 gRPC :>N2O J
9M #%*!#% l gRPC-kotlin (https://github.com/rouzwawi/grpc-kotlin) • $/&0;M$)BA  • Stream >NE=/,G5

Agenda • gRPC
 • Protocol Buffers  • gRPC Java  • gRPC  JJUG CCC 2019 Spring #ccc_a1 49 

l API Gateway  API #! l ! REST
API Gateway REST-gRPC " l  ! gRPC  l   proto  %$ 50
 JJUG CCC 2019 Spring #ccc_a1 Service Service Service API Gateway Browser REST gRPC proto proto proto 

l gRPC &*"$ • %+ (,  !) • 

 

 • Protocol Bufferes 
POJO  gRPC # '  51 
   JJUG CCC 2019 Spring #ccc_a1 Domain Logic gRPC Service Web Controller service message queue gRPC Stub JDBC Other service Database Kafka REST Other service Web Client External WebAPI 

2 A . I . I u b l p r t l 2 s . I dl A i go s • 1 1 • 2 AP em 52 . I JJUG CCC 2019 Spring #ccc_a1 

l - S CmsC PR B R C h gn S P CmsC • B iptb cotBr t P l . :: - S R D • : : :: / • : 2: / :: / • S : 2 P G vI L l S R • - . @ . @ N . / P B B td cot • . :: Nu - aC C y • - . @ t Cel CR 53 . :: - JJUG CCC 2019 Spring #ccc_a1 

54 JJUG CCC 2019 Spring #ccc_a1 // GrpcService  Spring  Bean 
 @GRpcService(interceptors = ValidationInterceptor.class) public class FizBuzReactorGrpcService extends ReactorFizBuzServiceGrpc.FizBuzServiceImplBase { // Spring Bean   
 @Autowired private FizBuzCalc cal; @Override public Mono fizBuzOne(Mono request) { return request.map(InputNumber::getNum) .map(cal::calc) .map(a -> FizBuzAnswer.newBuilder().setAnswer(a).build()); } 

l E / G C 55 JJUG CCC 2019 Spring #ccc_a1 syntax = "proto3"; import "google/api/annotations.proto"; // The fizbuz service definition. service FizBuzService { // calculate Fizbuz Answer rpc FizBuzOne (InputNumber) returns (FizBuzAnswer) { option (google.api.http) = { get: "/fizbuz/{num}" }; } rpc FizBuzRange (FromTo) returns (stream FizBuzAnswer) {} } http  Google api  proto   RPC  http  
REST    

l - 2 B https://github.com/grpc-ecosystem/grpc- gateway S 1 2 Rc ePurR w H fgR a tsPJ 2 R ). - h a • ( j N R aSiT RPC ySp • ) R aSp v Slo • . R a tsPJ HnGO 56 - 2 B JJUG CCC 2019 Spring #ccc_a1 

l CI2 GO t Ta tS • R RG t S l Gg tS u 2 aGO t • Ch R 2 PlL C l a t CI2 a n L • a C t PlL 2 S Ae lL C 59 t JJUG CCC 2019 Spring #ccc_a1 

l VP K • R l • R TP l V u C- a g VP K - l V l e H 60 V JJUG CCC 2019 Spring #ccc_a1 

l B B o B • Pe a BPe v • np g l S P e i • S P e C u • C r • ,, C ce i l Bv t B b B R b 61 Pe a JJUG CCC 2019 Spring #ccc_a1 

l
 62 

JJUG CCC 2019 Spring #ccc_a1 var stub = FizBuzServiceGrpc.newBlockingStub(ch).withInterceptors( new ClientInterceptor() { public ClientCall interceptCall( MethodDescriptor method, CallOptions callOptions, Channel next) { var call = next.newCall(method, callOptions); return new ForwardingClientCall.SimpleForwardingClientCall<>(call){ @Override public void start(Listener responseListener, Metadata headers) { // 
 headers.put(Metadata.Key.of("cred", Metadata.ASCII_STRING_MARSHALLER), "password" ); super.start(responseListener, headers); } }; }}); 

l  
 
 63 



JJUG CCC 2019 Spring #ccc_a1 public class AuthenticateInterceptor implements ServerInterceptor { @Override public Listener interceptCall(ServerCall call, Metadata headers, ServerCallHandler next) { var cred = headers.keys().stream().filter(k -> k.equals(“cred”)).findFirst().get(); // Metadata & boolean ok = cred.equals(“password”); // '(, return new ForwardingServerCallListener .SimpleForwardingServerCallListener(next.startCall(call, headers)) { @Override // %$ , ) public void onMessage(ReqT message) { if (ok) { // '(OK,# super.onMessage(message); } else { // '(NG "+/ Status status = Status.UNAUTHENTICATED; // '(NG var metadata = new Metadata(); metadata.put( // 0. -  Metadata.Key.of(“error_detail”, Metadata.ASCII_STRING_MARSHALLER), “cred invalid”); call.close(status, metadata); // close RPC+/
*! Status, Metadata " } } 

l R • P R • C 64 JJUG CCC 2019 Spring #ccc_a1 public Listener interceptCall( ServerCall call, Metadata headers, ServerCallHandler next) { var cred = headers.keys().stream().filter(k -> k.equals("cred")).findFirst().get(); //   var username = getUsrename(cred); // # Context  username % ! var newContext = Context.current().withValue(Context.key("username"), username); //  Context " $
RPC Context.get("username').get()  return Contexts.interceptCall(newContext, call, headers, next); } 

l ) 1 . e PD )( ( J . 1 u J l O d P e )( ( lD . 1 t • 2 ai BPD p ) 1 . o D rD d ai P • BP Vfe DG m s P • n ) https://github.com/envoyproxy/protoc-gen-validate/ c i JP D J 65 ai JJUG CCC 2019 Spring #ccc_a1 

l R l l 66 JJUG CCC 2019 Spring #ccc_a1 // validator.proto syntax = “proto3”; package validator; import “google/protobuf/descriptor.proto”; // 
  range   extend google.protobuf.FieldOptions { Range range = 50000; } // Range  message Range { int32 min = 1; int32 max = 2; } package my.rpc; //  proto import import "validator/validator.proto"; message InputNumber { // 
 Range  int32 num = 1 [(validator.range) = {min:0, max:100}]; } 

l C 67 JJUG CCC 2019 Spring #ccc_a1 // AbstractMessage 
 % public void checkSample(AbstractMessage message) { // 
 "$ ! Map fields = message.getAllFields(); fields.forEach((desc, val) -> { // Range #' ! var rangeOpt = desc.getOptions().getAllFields().values().stream() .filter(v -> v instanceof Range).map(r -> (Range)r).findFirst(); // Range  & rangeOpt.ifPresent(range -> { if (range.getMin() <= (Integer)val && (Integer)val <= range.getMax()) { System.out.println("OK"); } }); }); } 

l e CH rH p vL H I x 69 p v JJUG CCC 2019 Spring #ccc_a1    
  i 4 nH C vo U v i /2 n C - L / G v o X TR T p v X TR C t sNP /2 7 A H G T k y o 

l R TH G a SP u l I H G I • e 4 / 2P n G 2P C R G C G • l HhyL 2P w l I L G AC • 4 7 L U S b t nG 70 T a S JJUG CCC 2019 Spring #ccc_a1  gRPC Server A gRPC Server B 
  

l NR s n Ev g u y D l R s , , h Ek E l llo Ee r SR n i c CD PD 71 SR S a JJUG CCC 2019 Spring #ccc_a1   gRPC Server A gRPC Server B DNS Consul Eureka,, Channel    
   

l ) l v ) • v ) no) ( • e e 72 JJUG CCC 2019 Spring #ccc_a1  gRPC Server A gRPC Server B 

 envoy envoy envoy xDS 

l  !!   
  JJUG CCC 2019 Spring #ccc_a1 API Gateway Browser REST gRPC gRPC gateway proto proto proto Spring boot gRPC envoy envoy Spring boot gRPC envoy Spring boot gRPC envoy Envoy 
 
 consul prometheus zipkin elasticsearch 73 73 

l Google7<.=-4 gPRC  >;6 8*9,0 l proto %( API %
#+:&) 
$ %!#  l  "'  2/?5 31 74   JJUG CCC 2019 Spring #ccc_a1 

$/17. 2(
*' • https://grpc.io/ • https://github.com/grpc-ecosystem • https://github.com/grpc/grpc-web • https://developers.google.com/protocol-buffers/ • https://github.com/pseudomuto/protoc-gen-doc • https://github.com/salesforce/reactive-grpc • https://github.com/grpc/grpc/blob/master/doc/PROTOCOL-HTTP2.md • https://github.com/envoyproxy/protoc-gen-validate/  0#49-)3! • https://github.com/kencharos/grpc-sample • gRPC%8
gRPC-gateway, gRPC-Web, L4L7!5"6+ • https://github.com/kencharos/envoy-service-discovery-spring • envoy
6+ !
kotlin
consul;& 75 *',: JJUG CCC 2019 Spring #ccc_a1 

THANK YOU