Package com.rabbitmq.stream

Interface ConsumerUpdateListener

public interface ConsumerUpdateListener

An interface for reacting to status changes of single active consumers.

An application uses the update(Context) callback to compute the offset to start consuming from when the consumer becomes active.

The application can also use the update(Context) callback to store the offset of the last message it processed when the consumer goes from active to passive.

This is especially useful when using manual server-side offset tracking or offset tracking from an external datastore.

See Also:

ConsumerBuilder.singleActiveConsumer(), ConsumerBuilder.manualTrackingStrategy(), ConsumerBuilder.noTrackingStrategy()

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static interface	ConsumerUpdateListener.Context	Information on the status change.

Method Summary

Modifier and Type	Method	Description
OffsetSpecification	update(ConsumerUpdateListener.Context context)	Callback when the consumer status change.

Method Detail

update

OffsetSpecification update(ConsumerUpdateListener.Context context)

Callback when the consumer status change.

The method must return the offset specification to resume consumption from when the consumer becomes active. The broker will use the value to initialize the dispatching of messages from the appropriate location.

The broker ignores the returned value when the consumer becomes inactive.

Parameters:

context - information on the status change

Returns:

the offset specification to consume from if the status is active