Module dk.cloudcreate.essentials.reactive

Package dk.cloudcreate.essentials.reactive

Class LocalEventBus

java.lang.Object

dk.cloudcreate.essentials.reactive.LocalEventBus

All Implemented Interfaces:

EventBus

public class LocalEventBus
extends Object
implements EventBus

Simple event bus that supports both synchronous and asynchronous subscribers that are registered and listening for events published within the local the JVM
You can have multiple instances of the LocalEventBus deployed with the local JVM, but usually one event bus is sufficient.

Example:

  LocalEventBus localEventBus    = new LocalEventBus("TestBus", 3, (failingSubscriber, event, exception) -> log.error("...."));

   localEventBus.addAsyncSubscriber(orderEvent -> {
             ...
         });

   localEventBus.addSyncSubscriber(orderEvent -> {
               ...
         });

   localEventBus.publish(new OrderCreatedEvent());
 

If you wish to colocate multiple related Event handling methods inside the same class and use it together with the LocalEventBus then you can extend the AnnotatedEventHandler class:

{@code
 public class OrderEventsHandler extends AnnotatedEventHandler {

See Also:

AnnotatedEventHandler

Constructor Summary

Constructors

Constructor	Description
LocalEventBus(String busName)	Create a LocalEventBus with the given name, using system available processors of parallel asynchronous processing threads
LocalEventBus(String busName, int parallelThreads)	Create a LocalEventBus with the given name, the given number of parallel asynchronous processing threads
LocalEventBus(String busName, int parallelThreads, OnErrorHandler onErrorHandler)	Create a LocalEventBus with the given name, the given number of parallel asynchronous processing threads
LocalEventBus(String busName, int parallelThreads, Optional<OnErrorHandler> optionalOnErrorHandler)	Create a LocalEventBus with the given name, the given number of parallel asynchronous processing threads
LocalEventBus(String busName, OnErrorHandler onErrorHandler)	Create a LocalEventBus with the given name, using system available processors of parallel asynchronous processing threads
LocalEventBus(String busName, Optional<OnErrorHandler> optionalOnErrorHandler)	Create a LocalEventBus with the given name, using system available processors of parallel asynchronous processing threads
LocalEventBus(String busName, reactor.core.scheduler.Scheduler asyncSubscribersScheduler, OnErrorHandler onErrorHandler)	Create a LocalEventBus with the given name, the given number of parallel asynchronous processing threads
LocalEventBus(String busName, reactor.core.scheduler.Scheduler asyncSubscribersScheduler, Optional<OnErrorHandler> optionalOnErrorHandler)	Create a LocalEventBus with the given name, the given number of parallel asynchronous processing threads

Method Summary

Modifier and Type	Method	Description
EventBus	addAsyncSubscriber(EventHandler subscriber)	Add an asynchronous subscriber/consumer
EventBus	addSyncSubscriber(EventHandler subscriber)	Add a synchronous subscriber/consumer
boolean	hasAsyncSubscriber(EventHandler subscriber)
boolean	hasSyncSubscriber(EventHandler subscriber)
EventBus	publish(Object event)	Publish the event to all subscribers/consumer First we call all asynchronous subscribers, after which we will call all synchronous subscribers on the calling thread (i.e.
EventBus	removeAsyncSubscriber(EventHandler subscriber)	Remove an asynchronous subscriber/consumer
EventBus	removeSyncSubscriber(EventHandler subscriber)	Remove a synchronous subscriber/consumer
String	toString()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

LocalEventBus

public LocalEventBus(String busName,
                     OnErrorHandler onErrorHandler)

Create a LocalEventBus with the given name, using system available processors of parallel asynchronous processing threads

Parameters:

busName - the name of the bus

onErrorHandler - the error handler which will be called if any subscriber/consumer fails to handle an event

LocalEventBus

public LocalEventBus(String busName)

Create a LocalEventBus with the given name, using system available processors of parallel asynchronous processing threads

Parameters:

busName - the name of the bus

LocalEventBus

public LocalEventBus(String busName,
                     Optional<OnErrorHandler> optionalOnErrorHandler)

Create a LocalEventBus with the given name, using system available processors of parallel asynchronous processing threads

Parameters:

busName - the name of the bus

optionalOnErrorHandler - optional error handler which will be called if any subscriber/consumer fails to handle an event
If Optional.empty(), a default error logging handler is used

LocalEventBus

public LocalEventBus(String busName,
                     int parallelThreads,
                     Optional<OnErrorHandler> optionalOnErrorHandler)

Create a LocalEventBus with the given name, the given number of parallel asynchronous processing threads

Parameters:

busName - the name of the bus

parallelThreads - the number of parallel asynchronous processing threads

optionalOnErrorHandler - optional error handler which will be called if any subscriber/consumer fails to handle an event
If Optional.empty(), a default error logging handler is used

LocalEventBus

public LocalEventBus(String busName,
                     int parallelThreads,
                     OnErrorHandler onErrorHandler)

Create a LocalEventBus with the given name, the given number of parallel asynchronous processing threads

Parameters:

busName - the name of the bus

parallelThreads - the number of parallel asynchronous processing threads

onErrorHandler - the error handler which will be called if any subscriber/consumer fails to handle an event

LocalEventBus

public LocalEventBus(String busName,
                     int parallelThreads)

Create a LocalEventBus with the given name, the given number of parallel asynchronous processing threads

Parameters:

busName - the name of the bus

parallelThreads - the number of parallel asynchronous processing threads

LocalEventBus

public LocalEventBus(String busName,
                     reactor.core.scheduler.Scheduler asyncSubscribersScheduler,
                     Optional<OnErrorHandler> optionalOnErrorHandler)

Create a LocalEventBus with the given name, the given number of parallel asynchronous processing threads

Parameters:

busName - the name of the bus

asyncSubscribersScheduler - the asynchronous event scheduler (for the asynchronous consumers/subscribers)

optionalOnErrorHandler - optional error handler which will be called if any subscriber/consumer fails to handle an event
If Optional.empty(), a default error logging handler is used

LocalEventBus

public LocalEventBus(String busName,
                     reactor.core.scheduler.Scheduler asyncSubscribersScheduler,
                     OnErrorHandler onErrorHandler)

Create a LocalEventBus with the given name, the given number of parallel asynchronous processing threads

Parameters:

busName - the name of the bus

asyncSubscribersScheduler - the asynchronous event scheduler (for the asynchronous consumers/subscribers)

onErrorHandler - the error handler which will be called if any subscriber/consumer fails to handle an event

Method Detail

publish

public EventBus publish(Object event)

Description copied from interface: EventBus

Publish the event to all subscribers/consumer
First we call all asynchronous subscribers, after which we will call all synchronous subscribers on the calling thread (i.e. on the same thread that the publish method is called on)

Specified by:

publish in interface EventBus

Parameters:

event - the event to publish

Returns:

this bus instance

addAsyncSubscriber

public EventBus addAsyncSubscriber(EventHandler subscriber)

Description copied from interface: EventBus

Add an asynchronous subscriber/consumer

Specified by:

addAsyncSubscriber in interface EventBus

Parameters:

subscriber - the subscriber to add

Returns:

this bus instance

removeAsyncSubscriber

public EventBus removeAsyncSubscriber(EventHandler subscriber)

Description copied from interface: EventBus

Remove an asynchronous subscriber/consumer

Specified by:

removeAsyncSubscriber in interface EventBus

Parameters:

subscriber - the subscriber to remove

Returns:

this bus instance

addSyncSubscriber

public EventBus addSyncSubscriber(EventHandler subscriber)

Description copied from interface: EventBus

Add a synchronous subscriber/consumer

Specified by:

addSyncSubscriber in interface EventBus

Parameters:

subscriber - the subscriber to add

Returns:

this bus instance

removeSyncSubscriber

public EventBus removeSyncSubscriber(EventHandler subscriber)

Description copied from interface: EventBus

Remove a synchronous subscriber/consumer

Specified by:

removeSyncSubscriber in interface EventBus

Parameters:

subscriber - the subscriber to remove

Returns:

this bus instance

hasSyncSubscriber

public boolean hasSyncSubscriber(EventHandler subscriber)

Specified by:

hasSyncSubscriber in interface EventBus

hasAsyncSubscriber

public boolean hasAsyncSubscriber(EventHandler subscriber)

Specified by:

hasAsyncSubscriber in interface EventBus

toString

public String toString()

Overrides:

toString in class Object