NATS for High Performance Microservice Messaging

Module 1: NATS essentials

• The NATS model compared to traditional brokers
• Subjects, tokens, wildcards, and subscription matching
• Clients, connections, and the nats CLI for quick checks

Module 2: Pub or sub and request or reply

• Publish or subscribe flow and fan out behavior
• Request or reply for service style interactions and timeouts
• When to use queue groups to spread work across workers

Module 3: Designing subjects and contracts

• Subject naming guidelines for domains and resources
• Message shape, headers, and idempotency basics
• Versioning strategies that keep producers and consumers stable

Module 4: Reliability and flow control without JetStream

• Reconnect and retry options and sensible timeouts
• Backpressure with queue groups and max in flight on the client
• Ordering expectations and small payload best practices

Module 5: JetStream basics for durability

• Streams, subjects, and retention options
• Consumers, ack policies, and delivery semantics
• Simple replay and at least once processing patterns

Module 6: Security and multi tenancy

• Authentication options including user or pass and nkey
• Accounts, imports, exports, and scoped access to subjects
• TLS basics and secret handling in a team environment

Module 7: Observability and troubleshooting

• Useful metrics such as pending, delivered, and consumer lag
• CLI tools for listing streams, consumers, and connections
• Common issues such as subject mismatches and permission errors

Module 8: Operating for performance

• Clustering at a glance and when to scale out
• Connection pooling and resource limits on clients
• A lightweight change and rollout checklist