Sends and receives messages from other isolates started by an Application.

Messages added to an instance of this type - through add - are broadcast to every isolate running a RequestSink. These messages are be received by listening to an instance of this type. A hub only receives messages from other isolates - it will not receive messages that it sent.

This type implements both Stream (for receiving events from other isolates) and Sink (for sending events to other isolates). Avoid Stream methods such as Stream.first, which will stop the hub from listening to future events.

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

    messageHub.listen((event) {
      if (event is Map && event["event"] == "broadcastMessage") {
        websocketsOnThisIsolate.forEach((s) => s.add(event["data"]);
      }
    });
Inheritance
  • Object
  • Stream
  • ApplicationMessageHub
Implements
  • Sink

Constructors

ApplicationMessageHub()

Properties

first → Future

Returns the first element of the 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>

Reports whether this stream contains any elements.

read-only, inherited
last → Future

Returns the last element of the stream.

read-only, inherited
length → Future<int>

Counts the elements in the stream.

read-only, inherited
runtimeType → Type

A representation of the runtime type of the object.

read-only, inherited
single → Future

Returns the single element.

read-only, inherited

Operators

operator ==(other) → bool

The equality operator.

inherited

Methods

add(event) → void

Sends a message to all other isolates.

close() → Future

Closes the sink.

listen(void onData(event), { Function onError, void onDone(), bool cancelOnError: false }) → StreamSubscription

Adds a listener for data events from other isolates.

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>

Creates a new stream with the events of a stream per original event.

inherited
asyncMap<E>(dynamic convert(T event)) → Stream<E>

Creates a new stream with each data event of this stream asynchronously mapped to a new event.

inherited
contains(Object needle) → Future<bool>

Checks 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 the stream, but signals when it's 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 value)) → Stream<S>

Creates a new stream from this stream that converts each element into zero or more events.

inherited
firstWhere(bool test(T element), { Object defaultValue() }) → Future

Finds the first element of this stream matching test.

inherited
fold<S>(S initialValue, S combine(S previous, T element)) → Future<S>

Reduces a sequence of values by repeatedly applying combine.

inherited
forEach(void action(T element)) → Future

Executes action on each data event of the stream.

inherited
handleError(Function onError, { bool test(error) }) → Stream

Creates a wrapper Stream that intercepts some errors from this stream.

inherited
join([String separator = "" ]) → Future<String>

Collects string of data events' string representations.

inherited
lastWhere(bool test(T element), { Object defaultValue() }) → Future

Finds the last element in this stream matching test.

inherited
map<S>(S convert(T event)) → Stream<S>

Creates a new stream that converts each element of this stream to a new value using the convert function.

inherited
noSuchMethod(Invocation invocation) → dynamic

Invoked when a non-existent method or property is accessed.

inherited
pipe(StreamConsumer streamConsumer) → Future

Pipe the events of this stream into streamConsumer.

inherited
reduce(dynamic combine(T previous, T element)) → Future

Reduces a sequence of values by repeatedly applying combine.

inherited
singleWhere(bool test(T element)) → 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 the data 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>

Chains this stream as the input of the provided StreamTransformer.

inherited
where(bool test(T event)) → Stream

Creates a new stream from this stream that discards some data events.

inherited