The role of Sidecars in Service Mesh control vs data plane.

Senior microservices engineering involves deep expertise in distributed systems theory, operational excellence, and architectural trade-offs.

At the senior level, the focus shifts from 'how to build' to 'how to scale and sustain'. This includes choosing between orchestration (central brain) and choreography (event-driven) for Sagas based on the business domain's complexity. It also involves ensuring system-wide observability through standard protocols like OpenTelemetry and enforcing security at every hop using mTLS and fine-grained RBAC.