The document discusses the transition from REST to gRPC, highlighting its advantages such as performance and efficiency using protocol buffers for data serialization. It includes a history of inter-process communication, details on implementing gRPC services, and a comparison of gRPC with REST-based APIs. The presentation invites attendees to visit their booth and participate in discussions and activities related to cloud-native technologies.

1. qaware.de
REST in Peace. Long live gRPC!
JavaLand 2022
Mario-Leander Reimer
mario-leander.reimer@qaware.de
@LeanderReimer

2. 2
Mario-Leander Reimer
Principal Software Architect
@LeanderReimer
#cloudnativenerd #qaware

3. Agenda
QAware | 3
QAware | 3
REST Beer
Service
REST Beer
Service
GET /api/beers
POST /api/beers
GET /api/beers/{asin}
PUT /api/beers/{asin}
DELETE /api/beers/{asin}
application/json
application/x-protobuf
gRPC Beer
Service
gRPC Beer
Service
gRPC Beer
Web UI
gRPC Beer
Client
gRPC Beer
Gateway
application/json
gRPC Beer
Nginx
gRPC
gRPC
gRPC
gRPC
gRPC
Web UI

4. https://github.com/lreimer/from-rest-to-grpc

5. “One cannot not communicate.”
- Paul Watzlawick

6. A Quick History Lesson on Inter Process Communication (IPC)
QAware | 6
DCOM
18.09.1996
Win95
RPC
14.01.1976
RFC 707
REST
2000
by Roy T.
Fielding
Java RMI
Feb 1997
JDK 1.1
HTTP/1.0
Mai 1996
RFC 1945
HTTP/1.1
Juni 1999
RFC 2616
HTTP/2.0
Mai 2015
RFC 7540
SOAP 1.2
2003
RPC
Oct 1983
Birrel und
Nielson
CORBA 1.0
Oct 1991
CORBA 2.0
August 1996
CORBA 2.3
Juni 1999
XML-RPC
1998
gRPC 1.0
Aug 2016
RESTful
Applications
2014 (?)
CORBA 3.0
July 2002

7. HTTP/1.1 200 OK
Content-Length: 139
Content-Type: application/json; charset=utf-8
Date: Wed, 10 Nov 2021 10:21:54 GMT
{
"alcohol": 5.6,
"asin": "B01AU6LWNC",
"brand": "Augustiner Brauerei München",
"country": "Germany",
"name": "Edelstoff Exportbier",
"type": "Lager"
}
GET /api/beers/B01AU6LWNC HTTP/1.1
Accept: application/json
Accept-Encoding: gzip, deflate
Connection: keep-alive
Host: localhost:8080
User-Agent: HTTPie/2.5.0
REST APIs
GET /api/beers
POST /api/beers
GET /api/beers/{asin}
PUT /api/beers/{asin}
DELETE /api/beers/{asin}

8. Richardson REST Maturity Model
QAware | 8
https://martinfowler.com/articles/richardsonMaturityModel.html
POST /bookingService HTTP/1.1
[various other headers]
<makeBookingRequest date="2010-01-04" persons="2"/>
POST /bookings HTTP/1.1
[various other headers]
<getBookingRequest id="ID-1234567890" user"lreimer"/>
GET /bookings/1234567890?user=lreimer HTTP/1.1
Accept: application/json
[various other headers]
GET /bookings/1234567890?user=lreimer HTTP/1.1
Accept: application/json
Link: /users/lreimer
[various other headers]

9. QAware | 9
1. The network is reliable
2. Latency is zero
3. Bandwidth is infinite
4. The network is secure
5. Topology doesn’t change
6. There is one administrator
7. Transport cost is zero
8. The network is homogeneous
The 8 Fallacies of Distributed Computing

10. Protocol Buffers are a language-neutral, platform-neutral
extensible mechanism for serializing structured data.
QAware | 10
■ https://developers.google.com/protocol-buffers
■ Like XML or JSON - just smaller, faster and easier!
■ Google Protobuf uses an efficient binary format to serialize data structures.
■ An Interface Definition Language (IDL) is used to define data structures and message payloads
■ Protocol Buffers supports code generation for Java, Python, Objective-C, C++, Kotlin, Dart, Go,
Ruby und C#.
■ Protobuf supports evolution as well as extension of schemas. Backwards and forwards
compatibility are supported:
– you must not change the tag numbers of any existing fields.
– you may delete fields.
– you may add new fields but you must use fresh tag numbers (i.e. tag numbers that were never
used in this protocol buffer, not even by deleted fields).

11. syntax = "proto3";
option java_package = "hands.on.grpc";
option java_outer_classname = "BeerProtos";
package beer;
message Beer {
string asin = 1;
string name = 2;
string brand = 3;
string country = 4;
float alcohol = 5;
enum BeerType{
IndianPaleAle = 0;
SessionIpa = 1;
Lager = 2;
}
BeerType type = 6;
}
// Protobuf marshalling
protoBeer = BeerProtos.Beer.newBuilder()
.setAsin("B079V9ZDNY")
.setName("Drunken Sailor")
.build();
byte[] bytes = protoBeer.toByteArray();
// Protobuf unmarshalling
protoBeer = BeerProtos.Beer.parseFrom(bytes);
$ ./gradlew generateProto
$ protoc -I=$SRC_DIR --java_out=$DST_DIR $SRC_DIR/beer.proto

12. gRPC. A modern, high performance, open source and
universal RPC framework.
■ Uses HTTP/2 as modern Web-friendly transport protocol (Multiplexing, TLS, compression, …)
■ Supports several types of communication: classic request-response as well as streaming from
Client-side, Server-side, Uni- and Bi-Directional
■ Uses Protocol Buffers as efficient binary payload format
■ Support various load balancing options: proxy, client-side and look-aside balancing
■ Flexible support for tracing, health checks and authentication
■ Client and server code can be generated from the IDL easily for several languages
– https://github.com/grpc/grpc-go
– https://buf.build
■ gRPC Gateway and gRPC Web projects from the ecosystem enable good interoperability
– https://grpc-ecosystem.github.io/grpc-gateway/
– https://grpc.io/docs/platforms/web/quickstart/
■ gRPC is a CNCF incubating project QAware | 12

13. syntax = "proto3";
option java_package = "hands.on.grpc";
option java_outer_classname = "BeerProtos";
import "google/protobuf/empty.proto";
package beer;
service BeerService {
rpc AllBeers (google.protobuf.Empty) returns (GetBeersResponse) {}
rpc GetBeer (GetBeerRequest) returns (GetBeerResponse) {}
rpc CreateBeer (CreateBeerRequest) returns (google.protobuf.Empty) {}
rpc UpdateBeer (UpdateBeerRequest) returns (google.protobuf.Empty) {}
rpc DeleteBeer (DeleteBeerRequest) returns (google.protobuf.Empty) {}
}
// more Protobuf message definitions ...

14. Come and enjoy a Cloud Fitness Espresso,
take part in our awesome price draw,
and don't miss our epic Cloud Native Battle “gRPC vs REST”!
Meet us at Booth #208

15. qaware.de
QAware GmbH
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81549 München
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