Core Concepts of Azure Event Hubs

Azure Event Hubs is a highly scalable data streaming platform and event ingestion service. It can capture millions of events per second so you can develop more applications and services that use real-time data.

What is an Event Hub?

An Event Hub is the central entity within Event Hubs that acts as a message broker. It's a collection of event senders and receivers. Event Hubs are partitioned to support parallel processing of high-volume data streams.

Events

An event is a lightweight record of something that has happened in the system. It's a sequence of bytes. An event typically contains:

Event Body: The actual data payload, which can be any format (JSON, Avro, custom binary).
Properties: Metadata associated with the event, such as timestamps, source identifiers, and custom application properties.

Producers

Producers are applications or services that send events to an Event Hub. They can send events individually or in batches. Producers can choose which partition to send an event to, or let Event Hubs distribute them evenly.

Consumers

Consumers are applications or services that read events from an Event Hub. Consumers typically operate within a consumer group to avoid duplicate processing and to distribute the workload.

Partitions

Partitions are ordered sequences of events. An Event Hub is divided into one or more partitions. Events sent to a partition are stored in the order they are received. Partitions enable Event Hubs to scale horizontally.

Key Benefit: Each partition can be processed independently by a separate consumer, allowing for parallel data ingestion and processing.

Consumer Groups

A consumer group is a unique view of an Event Hub. Each consumer group enables an independent reading of events from the Event Hub, with each consumer within the group processing a unique subset of the partitions. This allows multiple applications to consume the same event stream without interfering with each other.

For example, one consumer group might be used for real-time analytics, while another might be used for archiving data to a data lake.

Partition Key

When a producer sends an event to an Event Hub without specifying a partition, Event Hubs uses the partition key to determine which partition the event is sent to. Events with the same partition key will always be sent to the same partition. This ensures that events related to a specific entity (e.g., a device ID, a user ID) are processed in order.

Offsets

An offset is a unique, contiguous number representing the position of an event within a partition. Consumers use offsets to track their progress and resume reading from where they left off.

Throughput

Event Hubs are designed for high throughput. The number of partitions directly impacts the maximum ingress and egress throughput. By increasing the number of partitions, you can increase the overall throughput of the Event Hub.

                Scalability: Event Hubs offers auto-inflate capabilities, allowing you to automatically increase the number of throughput units (TUs) or partitions as your event volume grows.
            

Key Takeaways

Event Hub: The core messaging entity.
Events: Records of occurrences, consisting of body and properties.
Producers: Send events.
Consumers: Read events.
Partitions: Ordered streams within an Event Hub, enabling parallel processing.
Consumer Groups: Independent views of an Event Hub for different applications.
Partition Key: Ensures ordered delivery for related events.
Offsets: Track consumer progress within a partition.

Understanding these core concepts is fundamental to effectively leveraging Azure Event Hubs for your event-driven architectures.

Developer's Guide