INTERFACE by apidays 2023 - APIs with bounded contexts, Jose Haro Peralta, microapis.io

INTERFACE by apidays 2023
APIs for a “Smart” economy. Embedding AI to deliver Smart APIs and turn into an exponential organization
June 28 & 29, 2023

APIs with bounded contexts: modelling APIs with domain-driven design
Jose Haro Peralta, Author, Instructor, Consultant at microapis.io

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Transcript

1. APIs with Bounded Contexts Better design with domain-driven APIs José Haro Peralta Consultant, author, and instructor Founder of microapis.io APIDays Interface June 29, 2023
3. $ whoami • I’m Jose • Consultant, author, instructor • Author of Microservice APIs • Founder of microapis.io @JoseHaroPeralta @microapis
4. Relio https://getrelio.com/
5. Connect with me!  Twitter: @JoseHaroPeralta  GitHub: @abunuwas  Newsletter: https://microapis.substack.com  LinkedIn: https://www.linkedin.com/in/jose-haro-peralta/
6. Giveaway!  3 ebook copies of Microservice APIs  15 free signups for Build APIs with Python https://bit.ly/apidays-int
7. Agenda  Why is API design difficult?  How DDD helps us design better APIs  How do we model flows?
8. API-First
9. API design has a direct impact on user experience
12. API design is difficult Raw materials:  URLs  HTTP methods  Status codes  Schemas  HTTP headers
13. Heuristics are a means to an end CRUD heuristic  Create  Read  Update  Delete CRUD vs CRUDE APIs
14. DDD can help!
15. What is DDD?  Align software with business  Incorporate the language of the business  Create a Ubiquitous Language  Under the processes and flows of the business  Facilitate conversations between software and business
16. Domains, subdomains, and bounded contexts  Domain represents the core area of the business  Subdomain represents a specific area of the business  A bounded context is a space within which the vocabulary acquires specific meaning
19. Sources: • https://www.amdocs.com/insights/blog/event-storming • https://developer.ibm.com/tutorials/reactive-in-practice-1/
24. How do we model operations in APIs? 1. Customer adds items to the cart. 2. Customer proceeds to check out. 3. After applying coupons, discounts, and so on, the system calculates the total. 4. Customer selects a payment method and enters payment details. 5. System processes payment. 6. System confirms the order.
25. How do we model operations in APIs?
26. Heuristics for modeling operations  How do we model payment?  Paying is an operation, not an object or resource  Semantics of a POST => create a resource or send data for processing  POST will process the payment and create a payment object in our server  Return the outcome of this operation to the user  Using this heuristic, we can model nearly every business operation through the API.
27. Heuristics for modeling operations
29. How do we model flows in APIs? How do we represent the relationship between endpoints to document the flow?  HATEOAS  OpenAPI links  Workflows
30. Documenting flows with HATEOAS
31. Documenting flows with OpenAPI links
32. Documenting flows with workflows
33. https://github.com/OAI/sig-workflows
34. Benefits of using standards  Mock servers  Code generation  Documentation UIs (Swagger, Redoc, etc.)  Automatic testing
35. API testing  Fundamental to ensure accurate implementation  Necessary to deliver reliable integrations  Fuzzy testers like schemathesis  Property-based testing  Structural testing
36. API testing with schemathesis
37. Giveaway!  3 ebook copies of Microservice APIs  15 free signups for Build APIs with Python https://bit.ly/apidays-int
38. Further reading  I wrote some thoughts on bringing DDD and API design together in “APIs with Bounded Contexts”.  An insightful and pioneering overview of how domain-driven design can help and empower the API design process is James Higginbotham’s Principles of Web API Design. Another great resource that encourages a DDD approach to API design is Patterns for API Design, by Olaf Zimmerman, Mirko Stocker, Daniel Lübke, Uwe Zdun, and Cesare Pautasso.  For a comprehensive overview of API design, check out Arnaud Lauret’s The Design of Web APIs. David Biesack’s newsletter API Design Matters is also a rich source of ideas and information about good API design.  For more about API design heuristics for REST/OpenAPI, check out Josh Ponelat and Lukas Rosenstock’s Designing APIs with Swagger and OpenAPI. Check out Lukas’s talk “From Domain Model to API” for more examples of heuristics.  For ideas on modelling complex concepts like trust and liability, check out Martin Verraes and Rebecca Wirfs-Brock’s article “Models and Metaphors”.
39. Thanks for listening! Twitter: @JoseHaroPeralta GitHub: @abunuwas Newsletter: https://microapis.substack.com LinkedIn: https://www.linkedin.com/in/jose-haro-peralta/