NATS and NATS JetStream: Cloud-Native Messaging and Stream Storage

NATS is a high-performance, lightweight, cloud-native messaging system written in Go. Operating with sub-millisecond latencies and a binary footprint under 20MB, it supports Pub/Sub, Request-Reply RPC, and JetStream distributed streaming persistence.

⚡ Quick Dive

Core NATS vs. NATS JetStream

Feature Core NATS NATS JetStream
Delivery Model At-most-once (Fire-and-forget in RAM) At-least-once / Exactly-once
Storage Engine In-memory only (Zero disk persistence) Distributed disk log replicated via Raft
Consumer Model Push only Push or Pull consumers
Message Deduplication ❌ No ✅ Deduplication window
Key-Value Store ❌ No ✅ Embedded distributed KV store

Subject Hierarchies & Wildcards

  • Dot Separator (.): Tokens separated by dots (e.g. orders.us.processed).
  • Single-Token Wildcard (*): Matches exactly one token (orders.*.processed matches orders.us.processed but not orders.us.east.processed).
  • Full-Tail Wildcard (>): Matches one or more remaining tokens (orders.> matches all sub-subjects).

📖 Extended Guide

1. Synchronous Request-Reply over NATS

NATS implements request-reply RPC using dynamic Inbox Subjects:

Client                                                         Service
  │ ─── Publish to 'orders.create' (ReplyTo: '_INBOX.8x7a') ──► │ (Processes order)
  │ ◄── Publish to '_INBOX.8x7a' (Response: { orderId: 101 }) ─ │

2. JetStream Streams, Consumers & Deduplication

// Go JetStream Producer with Deduplication
js, _ := nc.JetStream()

// Publish message with Msg-Id for idempotent delivery
msg := nats.NewMsg("orders.created")
msg.Header.Set("Nats-Msg-Id", "order-uuid-12345")
msg.Data = []byte(`{"id":"order-uuid-12345","amount":99.99}`)

ack, err := js.PublishMsg(msg)
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