Complex System Integration and Interoperability Questions

This topic focuses on designing and operating reliable integrations between heterogeneous systems. It covers API and contract design, synchronous and asynchronous integration patterns, messaging and event based architectures, data model mapping and transformation, schema evolution and versioning, idempotency and retry semantics, cross system consistency and transaction patterns, adapter layers and middleware, contract testing and integration testing, monitoring and tracing across boundaries, and security and authentication between systems.