🔑 Cheatsheet: Azure Service Bus vs Event Grid vs Event Hub

🟢 Azure Service Bus (Messaging / Queue)

• What: Enterprise message broker.

• Pattern: Message Queue / Pub-Sub (guaranteed delivery).

• Use cases:

  • Order processing

  • Payment workflows

  • Decoupling microservices

• Features:

  • FIFO (ordered delivery)

  • Dead-letter queue

  • Scheduled & delayed messages

  • Transactions

• Analogy: Post office for reliable message delivery.

👉 Think: Business transactions where delivery must be guaranteed.

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🔵 Azure Event Grid (Event Routing / Pub-Sub)

• What: Event distribution service → routes events from source to subscribers.

• Pattern: Reactive event-driven (push-based, low latency).

• Use cases:

  • React to Blob storage changes

  • Trigger serverless functions on events

  • Notify microservices when state changes

• Features:

  • Serverless, fully managed

  • Push model, near real-time

  • Supports filtering & fan-out

• Analogy: Courier service that delivers events to subscribers in real-time.

👉 Think: Lightweight, reactive workflows and serverless integration.

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🟣 Azure Event Hub (Big Data Streaming / Ingestion)

• What: Big data event ingestion pipeline.

• Pattern: Streaming (millions of events/sec).

• Use cases:

  • IoT telemetry ingestion

  • Website clickstream

  • Real-time analytics (with Azure Stream Analytics / Spark)

• Features:

  • Partitioned, scalable event ingestion

  • Capture to Blob/Data Lake

  • Integrates with real-time analytics engines

• Analogy: Highway where millions of events flow continuously.

👉 Think: High-throughput streaming for analytics.

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📊 Quick Comparison

Feature	Service Bus 🟢	Event Grid 🔵	Event Hub 🟣
Type	Message broker	Event router	Event ingestion pipeline
Pattern	Queue / Pub-Sub	Reactive Event Pub-Sub	Streaming (log-based)
Message Volume	Medium (business msgs)	Low/medium (events)	Very high (millions/sec)
Delivery Guarantee	✅ Reliable, FIFO	At least once	At least once (with offsets)
Use Cases	Transactions, workflows	Serverless triggers	IoT, telemetry, analytics
Storage Duration	Until consumed	Short-lived events	Configurable retention (days)

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⚡ Quick Elevator Pitch Answer

“Azure Service Bus is for reliable business messaging like orders and payments, where delivery guarantees and FIFO are important.
Azure Event Grid is a lightweight event router for reactive workflows like triggering a function when a blob changes.
Azure Event Hub is for high-throughput event streaming, like IoT telemetry or clickstream analytics.

In short:

• Service Bus → Messaging

• Event Grid → Event routing

• Event Hub → Big data streaming.”