subscribe method
Implementation
Stream subscribe(String methodPrefix, [List params = const []]) {
var subscribable = _subscribables[methodPrefix];
if (subscribable == null) {
throw RpcException.methodNotFound(methodPrefix);
}
var controller = makeSubscription(subscribable, params);
request(subscribable.methodSubscribe, params).then((result) {
controller.sink.add(result);
});
return controller.stream;
}