provider_stream_provider.dart

import 'package:flutter/material.dart';
import 'package:provider/provider.dart';

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return StreamProvider<MyModel>( //                       <--- StreamProvider
      initialData: MyModel(someValue: 'default value'),
      create: (context) => getStreamOfMyModel(),
      child: MaterialApp(
        home: Scaffold(
          appBar: AppBar(title: Text('My App')),
          body: Row(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[

              Container(
                padding: const EdgeInsets.all(20),
                color: Colors.green[200],
                child: Consumer<MyModel>( //                    <--- Consumer
                  builder: (context, myModel, child) {
                    return RaisedButton(
                      child: Text('Do something'),
                      onPressed: (){
                        myModel.doSomething();
                      },
                    );
                  },
                )
              ),

              Container(
                padding: const EdgeInsets.all(35),
                color: Colors.blue[200],
                child: Consumer<MyModel>( //                    <--- Consumer
                  builder: (context, myModel, child) {
                    return Text(myModel.someValue);
                  },
                ),
              ),

            ],
          ),
        ),
      ),
    );
    
  }
}

Stream<MyModel> getStreamOfMyModel() { //                        <--- Stream
  return Stream<MyModel>.periodic(Duration(seconds: 1),
          (x) => MyModel(someValue: '$x'))
      .take(10);
}

class MyModel { //                                               <--- MyModel
  MyModel({this.someValue});
  String someValue = 'Hello';
  void doSomething() {
    someValue = 'Goodbye';
    print(someValue);
  }
}