The document discusses OpenAPI Generator, an open source code generator library that generates API clients, servers, and documentation from OpenAPI specifications. It supports over 40 programming languages and frameworks. The presentation introduces OpenAPI Generator and its capabilities, provides examples of how it can be used to generate clients for different languages from a single API specification, and discusses the speaker's use cases including SDK generation, infrastructure as code, and performance testing. It encourages contributions to the project and questions.

1. Open API Generator
The Babel Fish of the API World
Cliffano Subagio | Shine Solutions
Apidays Live Australia – 15 & 16 September 2021

2. About
Cliffano Subagio
Principal Engineer at Shine Solutions
Member of OpenAPI Generator Technical Committee

3. Agenda
1. The polyglot systems and the Babel fis
h
2. Intro to OpenAPI Generato
r
3. My use case scenario
s
4. Wrap up + let’s contribute

4. 1. The polyglot systems and the Babel Fish

5. © 2020 Shine
Solutions Group
Back in the 2000s,
I was a Java developer
5
• Monolithic J2EE application
s
• 100% pure Java mindset
within the community

6. Monolithic Application
6
Java

7.
YOW! 2012 talks
by Fred Georg
e
Micro Services Architecture
Language agnostic service
s
Programmer Anarchy
Use of Ruby, Clojure, C++, Node.js

8. Multi Services
8
Ruby
Clojure
node.js Go
Python
Java
.NET

9. If you stick one
in your ear
The Babel fish

10. You instantly
understand
anything sent to you
in any language

11. Multi Services
11
Ruby
Clojure
node.js Go
Python
Java
.NET

12. 2. Intro to OpenAPI Generator

13. OpenAPI Generator
13
• Open source code generator librar
y
• Written in Java, uses Mustache template
s
• Generates API clients, server stubs, doc
s
• Supports 40+ tech stack
s
• Community fork of Swagger CodeGen
• Almost 10k GitHub stars
Almost 2k contributors

14. How does it work?
14
OpenAPI
Specification
OpenAPI
Generator
API
Clients
API
Servers
API Docs
Swagger-Parser
Generator
Templates

15. Example: ipify
15
api.ipify.org
GET / ?format=json
200 OK
{ “ip”: “60.240.197.183” }

16. OpenAPI specification
16
metadata
paths
responses
schemas
parameters

17. Running the generator
17

18. Running the generator
18

19. What will be generated?
19
• Project structur
e
• OpenAPI Generator metadat
a
• READM
E
• CI confi
g
• Library dependencie
s
• Documentatio
n
• Unit test
s
• API client:
Clients, data model
s
• API server stubs:
Endpoints, controllers, payloads

20. Generated API clients
20
Python Ruby node.js

21. Generated API clients
21
Java

22. Example Ruby API client
22

23. Supported tech stacks
23

24. 3. My use case scenarios

25. SOA with custom ESB (mostly Java)
25
ESB
Identity
Service
Adapter
Service
Data
Service
Consolidation
Service
Routing
Service
Message
Service
Monitor
Service

26. SDK Clients for a REST API
26
API Gateway (OpenAPI)
node.js Python Go Java

27. Infrastructure as Code
27
Legacy
Enterprise
Application
CLI (node.js)
Ruby
API Client
Python
API Client
SpringBoot App
(Java)
Ansible Playbook
Puppet Module
InSpec Profile

28. Performance testing
28
Web
App
JMeter
JMX
CSV

29. Jenkins CI/CD
29
Swaggy-
Jenkins
CLI
Smart Light
Notifiers
Voice
App

30. Top three maintenance tips…
30
1. Integration testing
2. Integration testing
3. Integration testing

31. 31
OpenAPI Spec v2 OpenAPI Spec v3
OpenAPI Generator v2 OAG v3 v4 v5
Python 2 Python 3
Ruby 1.9 Ruby 2.3 Ruby 2.5 Ruby 2.6
My application changes
Dependency Vulnerabilities
Environment changes
Changes happen all the time!

32. 4. Wrap up + let’s contribute

33. Remember the Babel fish?
33
Ruby
Clojure
node.js Go
Python
Java
.NET

34. OpenAPI Generator
34
https://openapi-generator.tech
• Multi tech-stacks suppor
t
• Boilerplate code for fre
e
• Massive time saver

35. My first contribution
35
I optimised file downloading
in Ruby API client’s

36. Failed to allocate memory at 2Gb

37. 100Mb+ memory consumption

38. Your contributions are welcomed!
https://github.com/OpenAPITools/
openapi-generator

39. Helping OpenAPI Generator
If you find OpenAPI Generator useful,
please consider becoming a sponsor.
https://opencollective.com/
openapi_generator

40. Thank you! Any questions?
cliff.subagio@shinesolutions.com
linkedin.com/in/cliffano/

41. Resources
https://openapi-generator.tech/
https://github.com/OpenAPITools/openapi-generator/
https://en.wikipedia.org/wiki/
The_Hitchhiker%27s_Guide_to_the_Galaxy#Future_predictions
https://www.youtube.com/watch?v=YWqHkYtREAE
https://www.youtube.com/watch?v=cbFLGv41vBA
https://www.youtube.com/watch?v=sns1DknIwhQ
https://opencollective.com/openapi_generator
https://en.wikipedia.org/wiki/OpenAPI_Specification
https://swagger.io/specification/
https://github.com/cliffano/openapi-ipify
https://github.com/cliffano/swaggy-jenkins
https://github.com/shinesolutions/swagger-aem
https://pixabay.com/photos/boat-shell-rowing-rowers-sport-3404551/