```
public interface EventListener
```
Event listeners are Event consumers. E.g. a listener can send email with notification or dump the event to an auditing database.

Author:

K. Benedyczak

Field Summary

Fields
Modifier and Type Field Description

static int DEFAULT_MAX_FAILURES

Method Summary

All Methods Instance Methods Abstract Methods Default Methods
Modifier and Type	Method	Description
`String`	`getId()`
`int`	`getMaxFailures()`
`boolean`	`handleEvent(Event event)`	Called only on events of a proper category, for which isWanted returned true.
`default void`	`init()`	Called before `EventListener` is being added to `EventProcessor`
`boolean`	`isAsync(Event event)`	This method should return whether async processing is allowed.
`boolean`	`isLightweight()`
`boolean`	`isWanted(Event event)`	This method should perform a fast filtering of uninteresting events.

- Field Detail
  - DEFAULT_MAX_FAILURES
```
static final int DEFAULT_MAX_FAILURES
```
    See Also:
    
    Constant Field Values
- Method Detail
  - isLightweight
```
boolean isLightweight()
```
    Returns:
    
    if true is returned then the listener's handle method will be invoked without persisting the event into database first. Therefore it is assumed that handler is going to perform an operation which nearly always succeeds. Otherwise the event is stored in DB first and if the handle method fails or throws an exception then the handling will be repeated after some time.
  - isWanted
```
boolean isWanted(Event event)
```
    This method should perform a fast filtering of uninteresting events.
    
    Returns:
    
    true if the event should be handled by this listener
  - isAsync
```
boolean isAsync(Event event)
```
    This method should return whether async processing is allowed. Otherwise processing is done immediately.
    
    Returns:
    
    true if the event should be handled in async mode.
  - handleEvent
```
boolean handleEvent(Event event)
```
    Called only on events of a proper category, for which isWanted returned true.
    
    Parameters:
    
    event -
    
    Returns:
    
    true if the event was processed successfully. Returning false is relevant only for the heavy-weight listeners.
  - getId
```
String getId()
```
    Returns:
    
    system unique and constant ID of the listener instance. It is suggested to form it from the full class name concatenated with listener name if it can have many instances.
  - getMaxFailures
```
int getMaxFailures()
```
    Returns:
    
    after how many failures the system should give up sending the event. It is suggested to return DEFAULT_MAX_FAILURES
  - init
```
default void init()
```
    Called before EventListener is being added to EventProcessor

Interface EventListener

Field Summary

Method Summary

Field Detail

DEFAULT_MAX_FAILURES

Method Detail

isLightweight

isWanted

isAsync

handleEvent

getId

getMaxFailures

init