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Integration
Message Channels
Publish-Subscribe Channel
Broadcast to all subscribers — every listener gets a copy of every message.
Intent & Description
Real-world Use Case
User signup event — UserRegistered published to a Pub-Sub topic. Email service sends a welcome email. Analytics service tracks the signup. Recommendation engine initializes preferences. All three react independently. Marketing team adds a fourth service (loyalty program) — zero changes to the publisher or other consumers.
Source
📌 TL;DR
Pub-Sub Channel = broadcast. One publish, N deliveries. Every subscriber gets every message. Add subscribers without touching the publisher. The backbone of event-driven systems.
Advantages
- One publisher, N subscribers — zero coupling between publisher and consumers
- Adding subscribers requires no changes to publisher or existing consumers
- Naturally decoupled — each subscriber processes independently at its own pace
- Core pattern for event-driven architecture
Disadvantages
- All subscribers receive all messages — use Message Filter for selective consumption
- No load balancing between subscribers — each gets every message (use Competing Consumers within each subscriber group)
- Publisher has no visibility into whether consumers processed the message
- Message volume multiplies with subscriber count — broker storage and bandwidth scale with N