Designing focuses on the core principles while creating web services. Instead of coding from the start, we will describe how to design a web service first, and then make it ready for coding. In this chapter, we will describe OpenAPI principles and implementation principles, which will help you when you design your own web services. This will help your web service support future changes and requirements. Finally, we will spend some time describing what to expose on a web service and what to accept when receiving a request.

The following topics will be covered in this chapter:

• API-first concepts
• The OpenAPI Specification
• Design maturity and implementation
• Minimal API surface
• Robustness and extendibility
• Swagger tooling