If have an observable and you subscribe it twice, those tow subscritions have no connection.
console.clear();
var Observable = Rx.Observable;
var _id = 1; var source = Observable.create(function(Observe){
var myId = _id++;
Observe.onNext('Observable ' + myId);
setTimeout(function(){
Observe.onNext('Observable... ' + myId);
Observe.onCompleted();
}, 1000);
}); var subscrition1 = source.subscribe(function onNext(x){
console.log('Observable 1: ' + x);
}); var subscrition2 = source.subscribe(function onNext(x){
console.log('Observable 2: ' + x);
});
Result:
/*"Observable 1: Observable 1"
"Observable 2: Observable 2"
"Observable 1: Observable... 1"
"Observable 2: Observable... 2"*/
publish():
Returns an observable sequence that is the result of invoking the selector on a connectable observable sequence that shares a single subscription to the underlying sequence.
console.clear();
var Observable = Rx.Observable;
var _id = 1; var source = Observable.create(function(Observe){
var myId = _id++;
Observe.onNext('Observable ' + myId);
setTimeout(function(){
Observe.onNext('Observable... ' + myId);
Observe.onCompleted();
}, 1000);
});
var published = source.publish(); var subscrition1 = published.subscribe(function onNext(x){
console.log('Observable 1: ' + x);
}); var subscrition2 = published.subscribe(function onNext(x){
console.log('Observable 2: ' + x);
}); var connection = published.connect();
Results:
/*
"Observable 1: Observable 1"
"Observable 2: Observable 1"
"Observable 1: Observable... 1"
"Observable 2: Observable... 1"
*/
You can see the result just have one single subscrition then.
You can dispose the connection:
connection.dispose();
Results:
/*"Observable 1: Observable 1"
"Observable 2: Observable 1"*/
There is a problem when you connect the published observables at different place.
var Observable = Rx.Observable;
var _id = 1; var source = Observable.create(function(Observe){
var myId = _id++;
Observe.onNext('Observable ' + myId);
setTimeout(function(){
Observe.onNext('Observable... ' + myId);
Observe.onCompleted();
}, 1000);
});
var published = source.publish();
var connection = published.connect(); var subscrition1 = published.subscribe(function onNext(x){
console.log('Observable 1: ' + x);
}); var subscrition2 = published.subscribe(function onNext(x){
console.log('Observable 2: ' + x);
}); //var connection = published.connect();
Results:
/*"Observable 1: Observable... 1"
"Observable 2: Observable... 1"*/
If we move the connect() funciton up before subscribe(). Then we missed the very first console.log(); It means connection is already start, but no one subscribe it yet.
Therefore, we don't use publish() funciton alone, more than often we use publish().refCount() function together.