ApplicationMessageHub class Null safety

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"]);
      }
    });
Inheritance
Implemented types

Constructors

ApplicationMessageHub()

Properties

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

Methods

add(dynamic event) → void
Sends a message to all other hubs.
override
any(bool test(dynamic element)) Future<bool>
Checks whether test accepts any element provided by this stream.
inherited
asBroadcastStream({void onListen(StreamSubscription subscription)?, void onCancel(StreamSubscription subscription)?}) Stream
Returns a multi-subscription stream that produces the same events as this.
inherited
asyncExpand<E>(Stream<E>? convert(dynamic event)) Stream<E>
Transforms each element into a sequence of asynchronous events.
inherited
asyncMap<E>(FutureOr<E> convert(dynamic 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
close() Future
Closes the sink.
override
contains(Object? needle) Future<bool>
Returns whether needle occurs in the elements provided by this stream.
inherited
distinct([bool equals(dynamic previous, dynamic 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(dynamic element)) Future<bool>
Checks whether test accepts all elements provided by this stream.
inherited
expand<S>(Iterable<S> convert(dynamic element)) Stream<S>
Transforms each element of this stream into a sequence of elements.
inherited
firstWhere(bool test(dynamic element), {dynamic orElse()?}) Future
Finds the first element of this stream matching test.
inherited
fold<S>(S initialValue, S combine(S previous, dynamic element)) Future<S>
Combines a sequence of values by repeatedly applying combine.
inherited
forEach(void action(dynamic 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(dynamic element), {dynamic orElse()?}) Future
Finds the last element in this stream matching test.
inherited
listen(void onData(dynamic event)?, {Function? onError, void onDone()?, bool? cancelOnError = false}) StreamSubscription
Adds a listener for messages from other hubs.
override
map<S>(S convert(dynamic 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(dynamic previous, dynamic element)) Future
Combines a sequence of values by repeatedly applying combine.
inherited
singleWhere(bool test(dynamic 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(dynamic 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(dynamic element)) Stream
Forwards data events while test is successful.
inherited
timeout(Duration timeLimit, {void onTimeout(EventSink 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
A string representation of this object.
inherited
transform<S>(StreamTransformer<dynamic, S> streamTransformer) Stream<S>
Applies streamTransformer to this stream.
inherited
where(bool test(dynamic event)) Stream
Creates a new stream from this stream that discards some elements.
inherited

Operators

operator ==(Object other) bool
The equality operator.
inherited