Application Programming Interface Design and Integration Questions

Designing Application Programming Interfaces and selecting communication protocols to meet functional and non functional requirements. Candidates should be able to evaluate and choose between Representational State Transfer style resource oriented interfaces, Graph Query Language approaches, remote procedure call frameworks such as Google Remote Procedure Call, and message based or event driven integration patterns. Discussion should cover protocol and format trade offs including latency, throughput, consistency and ordering, binary versus text serialization formats such as protocol buffers or JavaScript Object Notation, developer ergonomics, client diversity, and resource consumption. Core design topics include contract design and schema evolution, versioning and backward compatibility strategies, pagination, filtering, sorting and error handling conventions, authentication and authorization models, rate limiting and quota strategies, caching choices, and gateway or proxy patterns. Integration concerns include direct synchronous calls, asynchronous message based decoupling, event streaming, and web hooks, plus client and server software development kits and data transformation between layers. Candidates should also explain resilience and reliability patterns such as timeouts, retries, circuit breaker and bulkhead techniques, and describe testing, monitoring and observability approaches including logging, metrics and distributed tracing. Finally, discussion should connect API and protocol choices to coupling, scalability, operational complexity, security posture, and developer productivity.