The Event-Driven Architecture Paradigm

When to Employ This Paradigm

For real-time or bursty workloads (e.g., IoT, financial trading, logistics) where loose coupling and asynchronous processing are beneficial.
When multiple, distinct subsystems must react to the same business or domain events.
When system extensibility is a high priority, allowing new components to be added without modifying existing services.

Model the Events: Define canonical event schemas, establish a clear versioning strategy, and assign ownership for each event type.
Select the Right Topology: For each data flow, make a deliberate choice between choreography (e.g., a simple pub/sub model) and orchestration (e.g., a central controller or saga orchestrator).
Engineer the Event Platform: Choose the appropriate event brokers or message meshes. Configure critical parameters such as message ordering, topic partitions, and data retention policies.
Plan for Failure Handling: Implement robust mechanisms for handling message failures, including Dead-Letter Queues (DLQs), automated retry logic, idempotent consumers, and tools for replaying events.
Instrument for Observability: Implement comprehensive monitoring to track key metrics such as consumer lag, message throughput, schema validation failures, and the health of individual consumer applications.

An Architecture Decision Record (ADR) that documents the event taxonomy, the chosen broker technology, and the governance policies (e.g., for naming, versioning, and retention).
A centralized schema repository with automated CI validation and consumer-driven contract tests.
Operational dashboards for monitoring system-wide throughput, consumer lag, and DLQ depth.

Hidden Coupling through Events:
- Mitigation: Consumers may implicitly depend on undocumented event semantics or data fields. Publish a formal event catalog or schema registry and use linting tools to enforce event structure.
Operational Complexity and "Noise":
- Mitigation: Without strong observability, diagnosing failed or "stuck" consumers is extremely difficult. Enforce the use of distributed tracing and standardized alerting across all event-driven components.
"Event Storming" Analysis Paralysis:
- Mitigation: While event storming workshops are valuable, they can become unproductive if not properly managed. Keep modeling sessions time-boxed and focused on high-value business contexts first.

Event Driven v1.1 - Enhanced

Kaynak: Enterprise Integration Patterns & AWS Event-Driven Guide

Tracing: OpenTelemetry ile request zincirini (Producer -> Broker -> Consumer) izle.
Lag: Consumer lag süresini monitör et (Alarm kur).

Aşama	Doğrulama
1	Event schema değişikliği geriye dönük uyumlu mu?
2	Aynı event iki kere gelirse sistem bozuluyor mu?
3	Sistem çöküp kalktığında kayıp mesaj var mı?