Event-Driven Architect

Purpose

Provides expertise in designing and implementing event-driven architectures. Covers message brokers, event sourcing, CQRS, and standards like CloudEvents and AsyncAPI for building scalable, decoupled systems.

When to Use

• Designing event-driven architectures
• Implementing message queues and brokers
• Building event sourcing systems
• Implementing CQRS patterns
• Creating AsyncAPI specifications
• Designing event mesh topologies
• Building asynchronous microservices

Quick Start

Invoke this skill when:

• Designing event-driven architectures
• Implementing message queues and brokers
• Building event sourcing systems
• Implementing CQRS patterns
• Creating AsyncAPI specifications

Do NOT invoke when:

• Building synchronous REST APIs (use api-designer)
• Setting up Kafka infrastructure (use data-engineer)
• Building workflow orchestration (use workflow-orchestrator)
• Designing GraphQL APIs (use graphql-architect)

Decision Framework

Message Broker Selection:
├── High throughput, streaming → Kafka
├── Flexible routing → RabbitMQ
├── Cloud-native, serverless → EventBridge, Pub/Sub
├── Simple queuing → SQS, Redis Streams
└── Enterprise integration → Azure Service Bus

Pattern Selection:
├── Audit/replay needed → Event Sourcing
├── Read/write separation → CQRS
├── Simple async → Pub/Sub
├── Guaranteed delivery → Transactional outbox
└── Complex routing → Message router

Core Workflows

1. Event-Driven System Design

1. Identify domain events
2. Define event schemas (CloudEvents)
3. Choose message broker
4. Design topic/queue structure
5. Define consumer groups
6. Plan dead letter handling
7. Document with AsyncAPI

2. Event Sourcing Implementation

1. Define aggregate boundaries
2. Design event types
3. Implement event store
4. Build projection handlers
5. Create read models
6. Handle schema evolution
7. Plan snapshot strategy

3. AsyncAPI Specification

1. Define servers and protocols
2. Describe channels (topics/queues)
3. Define message schemas
4. Document operations (pub/sub)
5. Add security schemes
6. Generate documentation
7. Enable code generation

Best Practices

• Use CloudEvents format for interoperability
• Design idempotent consumers
• Implement dead letter queues
• Version event schemas carefully
• Monitor consumer lag
• Plan for at-least-once delivery

Anti-Patterns

Anti-Pattern	Problem	Correct Approach
Synchronous over async	Defeats purpose	Use proper patterns
No idempotency	Duplicate processing	Design idempotent handlers
Ignoring order	Data consistency issues	Partition by key if needed
Huge events	Network overhead	Small events, fetch details
No schema evolution	Breaking changes	Versioning strategy