Once requirements are understood, you identify the most appropriate integration mechanism. For synchronous interactions and request–response needs, REST or GraphQL may be ideal. For decoupled interactions, high-volume throughput, or partner variability, asynchronous messaging (queues, streams) may be better. For systems needing real-time or event-driven reactions, event publishing/subscription patterns are selected. This step ensures that the architecture is fit-for-purpose and aligns with partner capabilities and client platform constraints.