IStatefulComponent (Storm 2.7.1 API)

All Superinterfaces:

IComponent, Serializable

All Known Subinterfaces:

IStatefulBolt<T>, IStatefulWindowedBolt<T>

All Known Implementing Classes:

BaseStatefulBolt, BaseStatefulWindowedBolt, PersistentWindowedBoltExecutor, StatefulWindowedBoltExecutor, StatefulWordCounter
```
public interface IStatefulComponent<T extends State>
extends IComponent
```
Common methods for stateful components in the topology.
A stateful component is one that has state (e.g. the result of some computation in a bolt) and wants the framework to manage its state.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`void`	`initState(T state)`	This method is invoked by the framework with the previously saved state of the component.
`void`	`preCommit(long txid)`	This is a hook for the component to perform some actions just before the framework commits its state.
`void`	`prePrepare(long txid)`	This is a hook for the component to perform some actions just before the framework prepares its state.
`void`	`preRollback()`	This is a hook for the component to perform some actions just before the framework rolls back the prepared state.

Methods inherited from interface org.apache.storm.topology.IComponent
declareOutputFields, getComponentConfiguration

- Method Detail
  - initState
```
void initState(T state)
```
    This method is invoked by the framework with the previously saved state of the component. This is invoked after prepare but before the component starts processing tuples.
    
    Parameters:
    
    state - the previously saved state of the component.
  - preCommit
```
void preCommit(long txid)
```
    This is a hook for the component to perform some actions just before the framework commits its state.
  - prePrepare
```
void prePrepare(long txid)
```
    This is a hook for the component to perform some actions just before the framework prepares its state.
  - preRollback
```
void preRollback()
```
    This is a hook for the component to perform some actions just before the framework rolls back the prepared state.