ApplicationMessageHub class

An object that sends and receives messages between ApplicationChannels.

You use this object to share information between isolates. Each ApplicationChannel has a property of this type. A message sent through this object is received by every other channel through its hub.

To receive messages in a hub, add a listener via listen. To send messages, use add.

For example, an application may want to send data to every connected websocket. A reference to each websocket is only known to the isolate it established a connection on. This data must be sent to each isolate so that each websocket connected to that isolate can send the data:

    router.route("/broadcast").linkFunction((req) async {
      var message = await req.body.decodeAsString();
      websocketsOnThisIsolate.forEach((s) => s.add(message);
      messageHub.add({"event": "broadcastMessage", "data": message});
      return Response.accepted();
    });

    messageHub.listen((event) {
      if (event is Map && event["event"] == "broadcastMessage") {
        websocketsOnThisIsolate.forEach((s) => s.add(event["data"]);
      }
    });

Constructors

ApplicationMessageHub()

Properties

first → Future
The first element of this stream.
read-only, inherited
hashCode → int
The hash code for this object.
read-only, inherited
isBroadcast → bool
Whether this stream is a broadcast stream.
read-only, inherited
isEmpty → Future<bool>
Whether this stream contains any elements.
read-only, inherited
last → Future
The last element of this stream.
read-only, inherited
length → Future<int>
The number of elements in this stream.
read-only, inherited
runtimeType → Type
A representation of the runtime type of the object.
read-only, inherited
single → Future
The single element of this stream.
read-only, inherited

Methods

add(dynamic event) → void
Sends a message to all other hubs. [...]
close() → Future
Closes the sink. [...]
listen(void onData(dynamic event), { Function onError, void onDone(), bool cancelOnError: false }) → StreamSubscription
Adds a listener for messages from other hubs. [...]
any(bool test(T element)) → Future<bool>
Checks whether test accepts any element provided by this stream.
inherited
asBroadcastStream({void onListen(StreamSubscription<T> subscription), void onCancel(StreamSubscription<T> subscription) }) → Stream
Returns a multi-subscription stream that produces the same events as this.
inherited
asyncExpand<E>(Stream<E> convert(T event)) → Stream<E>
Transforms each element into a sequence of asynchronous events.
inherited
asyncMap<E>(FutureOr<E> convert(T event)) → Stream<E>
Creates a new stream with each data event of this stream asynchronously mapped to a new event.
inherited
cast<R>() → Stream<R>
Adapt this stream to be a Stream<R>.
inherited
contains(Object needle) → Future<bool>
Returns whether needle occurs in the elements provided by this stream.
inherited
distinct([bool equals(T previous, T next) ]) → Stream
Skips data events if they are equal to the previous data event.
inherited
drain<E>([E futureValue ]) → Future<E>
Discards all data on this stream, but signals when it is done or an error occurred.
inherited
elementAt(int index) → Future
Returns the value of the indexth data event of this stream.
inherited
every(bool test(T element)) → Future<bool>
Checks whether test accepts all elements provided by this stream.
inherited
expand<S>(Iterable<S> convert(T element)) → Stream<S>
Transforms each element of this stream into a sequence of elements.
inherited
firstWhere(bool test(T element), { dynamic orElse() }) → Future
Finds the first element of this stream matching test.
inherited
fold<S>(S initialValue, S combine(S previous, T element)) → Future<S>
Combines a sequence of values by repeatedly applying combine.
inherited
forEach(void action(T element)) → Future
Executes action on each element of this stream.
inherited
handleError(Function onError, { bool test(dynamic error) }) → Stream
Creates a wrapper Stream that intercepts some errors from this stream.
inherited
join([String separator = "" ]) → Future<String>
Combines the string representation of elements into a single string.
inherited
lastWhere(bool test(T element), { dynamic orElse() }) → Future
Finds the last element in this stream matching test.
inherited
map<S>(S convert(T event)) → Stream<S>
Transforms each element of this stream into a new stream event.
inherited
noSuchMethod(Invocation invocation) → dynamic
Invoked when a non-existent method or property is accessed.
inherited
pipe(StreamConsumer streamConsumer) → Future
Pipes the events of this stream into streamConsumer.
inherited
reduce(dynamic combine(T previous, T element)) → Future
Combines a sequence of values by repeatedly applying combine.
inherited
singleWhere(bool test(T element), { dynamic orElse() }) → Future
Finds the single element in this stream matching test.
inherited
skip(int count) → Stream
Skips the first count data events from this stream.
inherited
skipWhile(bool test(T element)) → Stream
Skip data events from this stream while they are matched by test.
inherited
take(int count) → Stream
Provides at most the first count data events of this stream.
inherited
takeWhile(bool test(T element)) → Stream
Forwards data events while test is successful.
inherited
timeout(Duration timeLimit, { void onTimeout(EventSink<T> sink) }) → Stream
Creates a new stream with the same events as this stream.
inherited
toList() → Future<List>
Collects all elements of this stream in a List.
inherited
toSet() → Future<Set>
Collects the data of this stream in a Set.
inherited
toString() → String
Returns a string representation of this object.
inherited
transform<S>(StreamTransformer<dynamic, S> streamTransformer) → Stream<S>
Applies streamTransformer to this stream.
inherited
where(bool test(T event)) → Stream
Creates a new stream from this stream that discards some elements.
inherited

Operators

operator ==(dynamic other) → bool
The equality operator.
inherited