gRPC is a high performance, open-source universal RPC framework. A service definition can be simply created in Protocol Buffers. Libraries in a wide variety of languages are then automatically generating the interface objects based on the service definition. Also, gRPC is much faster as REST due to leveraging HTTP/2 and Protocol Buffers. This talk will first give an introduction into gRPC. Afterward, we will see gRPC in action by creating a Scala service and a Swift client in a live-coding session.

1. with Scala and Swift
Markus Jura

2. A high performance,
open-source universal RPC framework

3. WAIT
REMOTE PROCEDURE
CALLS
NOT AGAIN

4. CORBA HELLO WORLD
import HelloApp.*;
import org.omg.CosNaming.*;
import org.omg.CosNaming.NamingContextPackage.*;
import org.omg.CORBA.*;
import org.omg.PortableServer.*;
import org.omg.PortableServer.POA;
import java.util.Properties;
class HelloImpl extends HelloPOA {
private ORB orb;
public void setORB(ORB orb_val) {
orb = orb_val;
}
// implement sayHello() method
public String sayHello() {
return "nHello world !!n";
}
// implement shutdown() method
public void shutdown() {
orb.shutdown(false);
}
}
public class HelloServer {
public static void main(String args[]) {
try{
// create and initialize the ORB
ORB orb = ORB.init(args, null);
// get reference to rootpoa & activate the POAManager
POA rootpoa = POAHelper.narrow(orb.resolve_initial_references("RootPOA"));
rootpoa.the_POAManager().activate();
// create servant and register it with the ORB
HelloImpl helloImpl = new HelloImpl();
helloImpl.setORB(orb);
// get object reference from the servant
org.omg.CORBA.Object ref = rootpoa.servant_to_reference(helloImpl);
Hello href = HelloHelper.narrow(ref);
// get the root naming context
// NameService invokes the name service
org.omg.CORBA.Object objRef =
orb.resolve_initial_references("NameService");
// Use NamingContextExt which is part of the Interoperable
// Naming Service (INS) specification.
NamingContextExt ncRef = NamingContextExtHelper.narrow(objRef);
// bind the Object Reference in Naming
String name = "Hello";
NameComponent path[] = ncRef.to_name( name );
ncRef.rebind(path, href);
System.out.println("HelloServer ready and waiting ...");
// wait for invocations from clients
orb.run();
}
catch (Exception e) {
System.err.println("ERROR: " + e);
e.printStackTrace(System.out);
}
System.out.println("HelloServer Exiting ...");
}
}

5. SOAP HELLO WORLD
HTTP/1.1 200 OK
Transfer-encoding: chunked
Content-type: text/xml;charset=utf-8
<?xml version="1.0" encoding="UTF-8"?>
<!-- Published by JAX-WS RI at http://jax-ws.dev.java.net.
RI's version is JAX-WS RI 2.1.1 in JDK 6. -->
<!-- Generated by JAX-WS RI at http://jax-ws.dev.java.net.
RI's version is JAX-WS RI 2.1.1 in JDK 6. -->
<definitions
xmlns:soap="http://schemas.xmlsoap.org/wsdl/soap/"
xmlns:tns="http://ws.mkyong.com/"
xmlns:xsd="http://www.w3.org/2001/XMLSchema"
xmlns="http://schemas.xmlsoap.org/wsdl/"
targetNamespace="http://ws.mkyong.com/"
name="HelloWorldImplService">
<types>
<xsd:schema>
<xsd:import namespace="http://ws.mkyong.com/"
schemaLocation="http://localhost:9999/ws/hello?xsd=1"></xsd:import>
</xsd:schema>
</types>
<message name="getHelloWorldAsString">
<part name="parameters" element="tns:getHelloWorldAsString"></part>
</message>
<message name="getHelloWorldAsStringResponse">
<part name="parameters" element="tns:getHelloWorldAsStringResponse"></part>
</message>
<portType name="HelloWorld">
<operation name="getHelloWorldAsString">
<input message="tns:getHelloWorldAsString"></input>
<output message="tns:getHelloWorldAsStringResponse"></output>
</operation>
</portType>
<binding name="HelloWorldImplPortBinding" type="tns:HelloWorld">
<soap:binding transport="http://schemas.xmlsoap.org/soap/http" style="document">
</soap:binding>
<operation name="getHelloWorldAsString">
<soap:operation soapAction=""></soap:operation>
<input>
<soap:body use="literal"></soap:body>
</input>
<output>
<soap:body use="literal"></soap:body>
</output>
</operation>
</binding>
<service name="HelloWorldImplService">
<port name="HelloWorldImplPort" binding="tns:HelloWorldImplPortBinding">
<soap:address location="http://localhost:9999/ws/hello"></soap:address>
</port>
</service>
</definitions>

6. GRPC HELLO WORLD
// Service definition
service Greeter {
rpc SayHello(HelloRequest) returns (HelloReply) {}
}
// Service implementation
override def sayHello(request: HelloRequest): Future[HelloReply] =
Future.successful(HelloReply(s"Hello ${request.name}"))

7. OVERVIEW
▪ Open source
▪ Developed by Google and Square
▪ HTTP/2
▪ Service and schema definition in protobuf
▪ Protobuf binary serialization
▪ Source code generation

8. HOW DOES IT WORK
Gateway Backend
gRPC
Impl
gRPC
Stub
gRPC
Stub
gRPC
Impl

9. SUPPORTED LANGUAGES
C++ Java Python
Go
Ruby
C#
Objective-C
Node.js
PHP
Android Java
Official support
Community support Scala
Kotlin
Swift
More
Haskell

10. BENEFITS
Streaming
PerformanceSimplicity
Interoperability
Reduced Network
Traffic
Consistency

11. IN THE REAL WORLD

12. GRPC IN ACTION

13. DEPENDENCIES PLUGINS.SBT
addSbtPlugin("com.thesamet" % "sbt-protoc" % "0.99.12")
libraryDependencies += "com.trueaccord.scalapb" %% "compilerplugin" % "0.6.6"

14. DEPENDENCIES BUILD.SBT
PB.targets in Compile := Seq(
scalapb.gen() -> (sourceManaged in Compile).value
)
lazy val scalaPbVersion = com.trueaccord.scalapb.compiler.Version.scalapbVersion
libraryDependencies ++= Seq(
"io.grpc" % "grpc-netty" % scalaPbVersion,
"com.trueaccord.scalapb" %% "scalapb-runtime-grpc" % scalaPbVersion
)

15. REQUEST-RESPONSE PATTERN
Passenger ServiceSynchronous
Non-blocking

16. DEMO

17. SERVER-PUSH PATTERN
Passenger Service
1. Initiate connection
Non-blocking
2. Push data frames
3. Close connection

18. DEMO

19. CLIENT-PUSH PATTERN
Passenger Service
1. Initiate connection
Non-blocking
2. Push data frames
3. Close connection

20. BI-DIRECTIONAL STREAMING PATTERN
Passenger Service
1. Initiate connection
Non-blocking
2. Push data frames
3. Close connection

21. DEMO

22. PERFORMANCE

23. PERFORMANCE BENCHMARK
# of requests # of clients total time per-request time
jsonrpc 300.000 1 8m 7s 1.6ms
gRPC 300.000 1 37s 0.12ms
gRPC 300.000 100 7s 0.02ms
▪ Requests on single TCP connection
▪ jsonrpc: HTTP/1.1 JSON
▪ gRPC: HTTP/2.0 Protobuf
https://blog.gopheracademy.com/advent-2015/etcd-distributed-key-value-store-with-grpc-http2/

24. PERFORMANCE BENCHMARK
jsonrpc gRPC delta
NSPerOp 487.271.046.903 36.716.116.701 -92,46 %
AllocsPerOp 32.747.687 25.221.256 -22,98 %
AllocedBytesPerOp 3.182.814.152 1.795.122.672 -43,60 %
▪ CPU and memory usage on single TCP connection
▪ jsonrpc: HTTP/1.1 JSON
▪ gRPC: HTTP/2.0 Protobuf
https://blog.gopheracademy.com/advent-2015/etcd-distributed-key-value-store-with-grpc-http2/

25. PERFORMANCE BENCHMARK
gRPC gRPC with 100 clients delta
NSPerOp 36.716.116.701 7.168.591.678 -80,48 %
AllocsPerOp 25.221.256 25.221.256 +0.04%
AllocedBytesPerOp 1.795.122.672 1.795.122.672 +0.04%
CPU and memory usage: 1 gRPC client vs. 100 gRPC clients
https://blog.gopheracademy.com/advent-2015/etcd-distributed-key-value-store-with-grpc-http2/

26. BEST PRACTICES

27. WITHOUT PRIMITIVE WRAPPERS
syntax = "proto3";
package io.moia;
message BookingRequest {
string userId = 1;
int32 passengers = 2;
Address pickupAddress = 3;
}
final case class BookingRequest(
userId: String = "",
passengers: Int = 0,
pickupAddress: scala.Option[io.moia.passenger.Address] = None
) extends com.trueaccord.scalapb.GeneratedMessage with ...
passenger.proto
BookingRequest.scala

28. DEFAULT VALUES
▪ All fields are optional in proto3
▪ Missing fields are set to their default value
▪ string: ""
▪ numbers: 0
▪ boolean: false

29. WITH PRIMITIVE WRAPPERS
import "google/protobuf/wrappers.proto";
message BookingRequest {
google.protobuf.StringValue userId = 1;
google.protobuf.Int32Value passengers = 2;
Address pickupAddress = 3;
}
final case class BookingRequest(
userId: scala.Option[String] = None,
passengers: scala.Option[Int] = None,
pickupAddress: scala.Option[io.moia.passenger.Address] = None
) extends com.trueaccord.scalapb.GeneratedMessage with ...
passenger.proto
BookingRequest.scala

30. SHARING PROTOBUF DEFINITIONS
▪ Separate code repository for Protobuf definitions
▪ Publish generated files per language to package manager
▪ Use packages as dependency on client and server
=> One source of truth
=> Clean versioning

31. THERE IS MORE..

32. LINKS
▪ gRPC: grpc.io
▪ ScalaPB: scalapb.github.io
▪ grpc-java: github.com/grpc/grpc-java
▪ grpc-swift: github.com/grpc/grpc-swift
▪ Introduction to HTTP/2: developers.google.com/http2
▪ passenger-grpc example: github.com/moia-dev/passenger-grpc

33. CREDITS
▪ Google and Square
▪ ScalaPB
▪ Nadav Samet (trueaccord)
▪ Kenji Yoshida (xuwei-k)
▪ grpc-swift
▪ Tim Burks (timburks)

34. Q & OPTION[A]