Pattern 12 / COMMS
Use this when asking another component for an immediate answer.
Request-Response (Synchronous) fits when asking another component for an immediate answer. Mechanism: client sends a request and blocks until the server returns success, failure, or timeout. Use it for user-facing APIs, authentication, validation, reads, and simple command flows. The toll: latency and failures propagate directly through synchronous call chains.
User-facing apis, authentication, validation, reads, and simple command flows.
Mobile app calling an api to fetch account balance.
Describe the pressure first, then the mechanism, then the cost. That keeps the design grounded.
Same pressure family