Package com.ibm.streams.operator.state

State management for operators.

See: Description

Interface Summary

Interface	Description
Checkpoint	Represents a checkpoint.
CheckpointContext	Context information that allows operators to create or restore checkpoint data of their state information.
ConsistentRegionContext	Context information for the consistent region the operator is in.
StateHandler	Handler for operator state.

Class Summary

Class	Description
DelegateStateHandler<T extends StateHandler>	TODO
OrderedStateHandlers	TODO

Enum Summary

Enum	Description
CheckpointContext.Kind	TODO

Package com.ibm.streams.operator.state Description

State management for operators. Operators generally fall into three categories for state:

• Stateless - Operator maintains no state related to stream processing, typically an input tuple is processed completely within the process method resulting in zero or more tuples being submitted, for example a filtering operator.
• Buffering - Operator processes a tuple partially within the process method, leaving outstanding work once the process method returns. For example a delay operator creates a list of tuples to be submitted later.
• Stateful - The operator maintains state related to tuple processing that persists across multiple calls to the process method. For example, windowing operators. Some stateful operators may also be buffering.

Buffering and stateful operators utilize StateHandler to manage state and its coordination within an SPL application. For example:

• a buffering operator provides a StateHandler implementation to drain its outstanding processing in a consistent region.
• a stateful operator provides a StateHandler implementation to persist its state for recovery after failure when in a consistent region or checkpointing.

Since:

InfoSphere® Streams Version 4.0