Comparing Azure Event Grid, Event Hubs, and Service Bus: Which One to Choose?

Introduction

Nowadays most organizations globally are embracing cloud-native technologies for real-time data processing and event-driven architectures. Microsoft Azure has three messaging services to offer them – Azure Event Grid, Azure Event Hubs, and Azure Service Bus. 

By learning exactly what sets these services apart, i.e., their unique architecture and applications – you can make a more informed decision when selecting the best fit for your needs. In this blog, we have compiled some necessary data regarding different messaging services of Microsoft Azure and a brief comparison between them to help you pick the best fit for your purpose. 

Azure Event Grid for Streamlined Event Distribution

Azure Event Grid is an event routing service with the capability to distribute massive amounts of events and is deeply integrated into cloud-native/serverless architectures. It works on a push-based publish-subscribe model, where publishers emit events and subscribers subscribe to them by defining what they require for processing.

Event Filtering and Routing: Azure Event Grid enables you to filter events on event properties, content, or types and hence define complex filters by which a subscriber would get only those events they want.

Event-Based Integrations: Event Grid enables developers to combine Azure native events (like Blob Storage or IoT Events) and form external events from custom apps and third-party systems making it a perfect solution for reactive applications.

Scalability: Azure Event Grid is a fully scalable, low-latency, and pay-as-you-go solution. It is ideal for lightweight, serverless event distribution use cases like serverless computing with Azure functions or automating workflows across systems using Logic Apps.

Best Use Cases: Event Grid is a good match for scenarios in reactive programming and serverless applications, such as calling a function on file creation in Blob Storage or providing notifications on status changes.

Azure Event Hubs for Real-Time Event Ingestion and Streaming

Azure Event Hubs is designed to ingest massive amounts of event stream and telemetry data from IoT devices, offering a fully managed big data streaming platform for high throughput scenarios.

Partitioning and Consumer Groups: Event Hubs uses partitioning to allow data to be processed concurrently across partitions and consumer groups, providing excellent scalability while allowing each consumer group its own cursor for replays of events.

Data Capture: The events are retained for up to 90 days (with premium plans) and enable event data to be captured as well as stored to be further analyzed, replayed, and used for compliance purposes.

Pull-based Model: Subscribers pull the data on the basis of their cursor, meaning they can replay or skip as needed making it perfect for big data scenarios where retaining and analyzing entire spans of data is critical.

Best Use Cases: Event Hubs work best with high-volume scenarios, such as big data ingestion pipelines and real-time analytics or telemetry processing for IoT devices. It is especially well-suited for processing large-scale streams of data, such as logs or sensor data from IoT devices.

Azure Service Bus for Enterprise-Grade Messaging Broker

Azure Service Bus is an enterprise-level messaging broker that enables the exchange of high-value messages, such as those used in finance transactions including multi-warehouse order processing and supply chain messaging, packed with advanced features, fully managed and ready to deliver. This ensures durable & reliable message delivery with a feature set geared towards an enterprise-grade scenario.

Messaging Patterns: Service Bus can accommodate queuing (one-to-one) and publish-subscribe (one-to-many) messaging patterns where sending applications send messages in a scheduled sequence. It provides more advanced features like message batching, transactions, and sessions for complex messaging scenarios.

Reliable Message Storage: Service Bus stores messages reliably with the ability to hold messages for up to 14 days, making it perfect for applications that need message persistence and data correctness, or in cases where a message needs to be persisted to ensure delivery even if a network break occurs.

Message Enrichment and Dead-Lettering: One of the features of Service Bus is the ability to enrich messages with more data related to it, as well as having dead-letter queues to store failed messages for later analysis. This is an important feature in mission-critical applications, where loss of message can lead to disaster.

Best Use Cases: Service Bus is great for enterprise messaging that requires high reliability, ordered delivery, and sophisticated message handling (transactions and dead-lettering), such as financial applications, inventory management, or customer order processing.

Comparing Key Features

Feature	Azure Event Grid	Azure Event Hubs	Azure Service Bus
Purpose	Event distribution, serverless workflows	Real-time data streaming and ingestion	Enterprise messaging with durability and reliability
Throughput	Moderate, optimized for event distribution	High, handles millions of events per second	Moderate, scalable for enterprise message handling
Latency	Low	Low	Moderate
Retention Period	Short	Up to 90 days (premium)	Long (up to 14 days)
Pricing Model	Consumption-based	Throughput unit-based	Pay-as-you-go with different tiers
Message Ordering	Not guaranteed	Guaranteed within a partition	FIFO is available through sessions
Best for	Serverless architectures, reactive applications	Big data pipelines, IoT telemetry, real-time analytics	Enterprise messaging, order processing, financial apps

Choosing the Right Service for Your Project

Event Grid: Use when you want a fully managed, serverless event routing service. Since Event Grid has a built-in integration with dozens of Azure services, and can route events in almost real-time, it is a perfect candidate for reactive programming.

Event Hubs: Perfect for event Streams and telemetry data at scale. Use Event Hubs for high-throughput low-latency data capture scenarios (e.g. IoT streaming) and when you require data retention for later analysis.

Service Bus: The right solution if you require enterprise-level messaging reliability and message persistence, transactions, or ordering. It supports advanced features such as dead-letter queues and sessions, which are essential for message-based applications that cannot lose messages, like those in financial systems or critical business processes.

FAQs

1. What is the difference between Azure Event Grid and Azure Event Hubs?

Azure Event Grid is a lightweight, event routing and distribution service that makes it an excellent fit for event-driven applications and serverless architectures. On the other hand, Azure Event Hubs is intended for high-throughput data ingestion and streaming, ideal for big data use cases and real-time analytics.

2. When to use Azure Event Grid over Service Bus?

You can use Azure Event Grid for real-time event notifications with push-based delivery and high scalability features, it is great for connecting different parties besides integrating Azure events. Azure Service Bus favors queues with pull-based message processing and extreme resilience, so it is useful for workflows using load leveling or those that want sequential messaging.

Conclusion

Choosing the appropriate Azure messaging service will depend on the specific needs of your application. Azure Event Grid provides a simplified mechanism for lightweight event-based applications that require real-time updates. When it comes to big data ingestion and analytics, Azure Event Hubs is the fastest method, meeting ultra-high throughput and scalability needs. 

Finally, if your application needs reliable and durable messaging since it is an enterprise application then Azure Service Bus would be the best choice as it has a comprehensive feature set for message resiliency and durability.