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Explain the concept of RESTful API

RESTAPIWeb ServicesHTTP

Question

What is RESTful API? Explain its principles and how it differs from SOAP.

Interview Answer

RESTful APIs are resource-oriented HTTP APIs that are stateless, cache-friendly, and use standard methods like GET, POST, PUT, PATCH, and DELETE. SOAP is protocol-heavy, XML-centric, and typically more rigid.

Explanation

REST emphasizes simplicity, scalability, and predictable semantics through HTTP. SOAP provides strict contracts and protocol-level standards but is heavier. For most modern web/mobile services, REST is preferred due to lower overhead and easier integration.

Key Points

  • REST is an architectural style, SOAP is a protocol
  • REST usually uses JSON; SOAP typically uses XML
  • Stateless design helps horizontal scaling
  • HTTP method semantics are core to REST API design

Common Mistakes

  • Calling any HTTP endpoint RESTful without proper resource design
  • Ignoring status codes and error contract consistency
  • Using verbs in URLs instead of resource nouns

Likely Follow-Up Questions

  • How would you version a REST API?
  • When would you choose SOAP over REST?
  • How do idempotency and retries work in REST?

Interview Timing

Target speaking time: about 4 minutes.

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