APIs and microservices for connecting AX and D365FO to the wider business

A useful API makes ownership, validation and failure behaviour explicit. It should not expose internal ERP implementation details simply because they are convenient to return.

Stable contracts allow Dynamics and surrounding systems to evolve at different speeds.

Queues and events remove fragile runtime dependencies and support retries, but they introduce at-least-once delivery, ordering and reconciliation requirements. Idempotency must be designed, not assumed.

Synchronous calls remain appropriate when the user needs an immediate functional answer. The architecture chooses according to the operation, not fashion.

Correlation identifiers, metrics, dead-letter handling and functional acknowledgements make failures diagnosable. A message accepted by infrastructure is not necessarily a business operation completed in the ERP.

Good integration makes that distinction visible to users and operators.