This package is a part of Event-driven architecture providing sending, listening, processing and receiving the events.

Simple Usage

The event(EventDTO) consists of 3 parts: a header (topic), a unique identifier and data. The topic consists of the type of the transmitted object (required) and the name of the event.
EventDTO class transporting Event in bus, but user can use clear data without EventDTO for example:

EventBus bus = EventBus();
//----- Without EventDTO
///listenEvent return Stream
///topic = 'int' 
///bus.listenEvent<int>()! can return null only if you set prefix becouse bus be search other EventBus with prefix in EventBusMaster
bus.listenEvent<int>()!.listen((event)=>print('int event:$event'));
///topic = 'int^test' 
bus.listenEvent<int>(eventName:'test')!.listen((event)=>print('int^test event:$event'));
///topic = 'int' 
bus.send<int>(1); //'int event:1'
bus.send(2); //'int event:2' in this case type event get automated
///topic = 'int^test' 
bus.send<int>(3,eventName:'test');////'int@test event:3'
//----- With EventDTO
bus
      .listenEventDTO<int>()!
      .listen((event) => print('topic ${event.topic} uuid:${event.uuid} event:${event.data}'));
bus
      .listenEventDTO<int>(eventName: 'test')!
      .listen((event) => print('topic ${event.topic} uuid:${event.uuid} event:${event.data}'));

When you call listenEvent method, you can set flag repeatLastEvent what send event after wait 1 millisecond or Duration

Used with prefix and EventBusMaster

EventBusMaster is a singltone what have knowledg about all created EventBus and use prefix to sort them. The Event Bus Master also provides the ability to send and receive events from different business, but if there is no bus, it will return null or false. If you use any bus to send by prefix and the bus prefix does not match the specified prefix, event will be send to EventBusMaster.

EventBus bus = EventBus();
EventBus busServices = EventBus(prefix: 'services');
/// get event from bus
EventBusMaster.instance.listenEvent<int>()!.listen((event) => print('int master event:$event'));
/// get event from busServices
EventBusMaster.instance
      .listenEvent<int>(prefix: 'services')!
      .listen((event) => print('int master services bus event:$event'));
  bus.send<int>(5);
  EventBusMaster.instance.send(6);
  EventBusMaster.instance.send(7, prefix: 'services');

The prefix can be used to divide the application into layers, for example: ViewModel - layers for stores the latest state of the models and does not delete unused nodes (more on this later).
App - layer in which the business logic.
AppModel the layer, like ViewModel , stores the latest data models necessary for the operation of the application.
Services and ServicesModel , respectively.

EventBus for Model

By default EventBus, clear not use(where event listeners ==0) event node, but if you add flag 'isBusForModel' in constructor, you get EventBus(EventModelController) what not clear event node. This EventModelController can be used by hold(resource manager) and update object(models, providers, command, interface and other).

EventBus Handler

EventBusHandlersGroup this interface for handler group. You can connect EventBusHandlersGroup to you event bus

///Event handler
typedef EventHandler<T> = Future<void> Function(
    EventDTO<T> event,

    ///send event to other listener
    EventEmitter<EventDTO<T>>? emit,
    {EventBus? bus,
    Completer<dynamic>? needComplete});


class TestHandlers implements EventBusHandlersGroup {
void connect(EventBusHandler bus) {
///if you have many void handler need use eventName
bus.addHandler<void>(getMasterData, eventName: 'getMasterData');
///if handle unique for object you can not set eventName
bus.addHandler<Test>(test);
}
...
void main()
{
  EventBus bus = EventBus(prefix: 'test');
  var handlers = TestHandlers();
  handlers.connect(bus);
  bus.send<void>(null,eventName:'getMasterData');//call getMasterData fn
  bus.send(Test());//call test fn
}

Method: Call

If event have handler, handler can processing needCompleter and complety it. Result of complety return from future.
if event no have handler or handler dont support needCompleter Future complete with Error

//wait result or error
try{
var r = await bus1.call('Hello');
}
catch (e)
{
      print(e);
}