Understanding Event Consumers

All Event Hubs consumers connect via the AMQP 1.0 session and events are delivered through the session as they become available. The client does not need to poll for data availability : Overview of features - Azure Event Hubs - Azure Event Hubs | Microsoft Docs

There's always a default consumer group in an event hub, and you can create up to the maximum number of consumer groups for the corresponding pricing tier. There can be at most 5 concurrent readers on a partition per consumer group; however it's recommended that there's only one active receiver on a partition per consumer group.

Consumer Groups on Partition

Naming Conventions for URI

//<my namespace>.servicebus.windows.net/<event hub name>/<Consumer Group #1>
//<my namespace>.servicebus.windows.net/<event hub name>/<Consumer Group #2>

Stream Offsets

An Offset is the position of an event within a partition (like a client-side cursor) and is a byte numbering of the event. It enables an event consumer (reader) to specify a point in the event stream from which they want to begin reading events.

Offset or Client-Side Cursor

Consumers are responsible for storing their own offset values outside of the Event Hubs service.

Checkpointing

It’s the process by which readers mark or commit their position within a partition event sequence. Each partition reader must keep track of its current position in the event stream, and can inform the service when it considers the data stream complete.