How make my own Stream - stream

Question

I have already try to understand the API doc, the articles about them, and this post: How do you create a Stream in Dart
I'm making a simple web app using WebSocket. Actually, it's working well, but I want add a feature (enjoy learn).
This is my class (can be optimized I guess)
library Ask;
import 'dart:html';
import 'dart:async';
import 'dart:convert';
class Ask {
final String addr;
String _protocol;
String _port;
WebSocket _ws;
bool openned;
Map<int, Completer> _completer_list = {};
int _counter = 0;
static final Map<String, Ask> _cache = <String, Ask>{};
factory Ask(String addr) {
if (_cache.containsKey(addr)) {
return _cache[addr];
} else {
final ask_server = new Ask._internal(addr);
_cache[addr] = ask_server;
return ask_server;
}
}
Ask._internal(this.addr);
Future<bool> open() {
if (openned)
return true;
_completer_list[0] = new Completer();
if (window.location.protocol == 'http:') {
_port = ':8080/ws';
_protocol = 'ws://';
} else {
_port = ':8443/ws';
_protocol = 'wss://';
}
_ws = new WebSocket(_protocol + addr + _port);
_ws.onOpen.listen((e) {
_get_data();
_get_close();
openned = true;
_completer_list[0].complete(true);
});
return _completer_list[0].future;
}
Future<String> send(Map data) {
bool check = false;
int id;
_completer_list.forEach((k, v) {
if (v.isCompleted) {
id = data['ws_id'] = k;
_completer_list[k] = new Completer();
_ws.send(JSON.encode(data));
check = true;
}
});
if (!check) {
_counter++;
id = data['ws_id'] = _counter;
_completer_list[id] = new Completer();
_ws.send(JSON.encode(data));
}
return _completer_list[id].future;
}
void _get_data() {
_ws.onMessage.listen((MessageEvent data) {
var response = JSON.decode(data.data);
_completer_list[response['ws_id']].complete(response);
});
}
void _get_close() {
_ws.onClose.listen((_) {
print('Server have been lost. Try to reconnect in 3 seconds.');
new Timer(new Duration(seconds: 3), () {
_ws = new WebSocket(_protocol + addr + _port);
_get_data();
_get_close();
_ws.onOpen.listen((e) => print('Server is alive again.'));
});
});
}
}
Example of use:
void showIndex() {
Element main = querySelector('main');
Ask connect = new Ask('127.0.0.1');
Map request = {};
request['index'] = true;
connect.open().then((_) {
connect.send(request).then((data) {
main.setInnerHtml(data['response']);
});
});
}
I would replace the then by a listen who will be canceled when the message will completed. By this way, I can add a progress bar, I think...
So my question, my send function can be a stream and keep my concept of one websocket for all ? (yes, if my function is used when a request is in progress, it's sent and if she's finish before the first, I recovered her properly. Thank you ws_id).
Thank you.

Answer 1

I think what you need is a StreamController
https://api.dartlang.org/apidocs/channels/stable/dartdoc-viewer/dart-async.StreamController