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
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
index
th 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