CSI RESTful API & Middleware Design 3

Question 1

Which middleware pattern stores frequently accessed data closer to the consumer to reduce upstream API calls?

Accepted Answer

Caching proxy

Answer

A caching proxy intercepts requests and returns stored responses when valid, reducing latency and backend load.

Question 2

A REST API must expose the same resource in both JSON and XML formats based on client preference. Which mechanism should it use?

Accepted Answer

HTTP Accept header content negotiation

Answer

Content negotiation via the Accept header is the HTTP-standard mechanism for clients to specify their preferred response format.

Question 3

What does the Richardson Maturity Model Level 3 (Hypermedia Controls) require of a REST API?

Accepted Answer

Responses that include links guiding clients to available next actions

Answer

Level 3 (HATEOAS) requires responses to embed hypermedia links so clients can discover and navigate possible state transitions.

Question 4

In middleware design, a circuit breaker transitions to the 'open' state when:

Accepted Answer

A configurable number of consecutive failures occurs

Answer

A circuit breaker opens after a defined failure threshold is reached, stopping further calls to the failing downstream service.

Question 5

Which REST API design practice best prevents over-fetching and under-fetching issues?

Accepted Answer

Supporting sparse fieldsets via query parameters like ?fields=id,name

Answer

Sparse fieldsets allow clients to request only the specific fields they need, reducing payload size and avoiding under-fetching.

(CSI) Certified System Integrator Practice Test