foobar

components.x-bar.js

import Ember from 'ember';

export default Ember.Component.extend({
  fooBar: Ember.inject.service('foo-bar'),
});

components.x-foo.js

import Ember from 'ember';

export default Ember.Component.extend({
  fooBar: Ember.inject.service('foo-bar'),
  foo: Ember.computed.alias('fooBar.foo'),
});

controllers.application.js

import Ember from 'ember';

export default Ember.Controller.extend({
  appName: 'Ember Twiddle',
  fooBar: Ember.inject.service('foo-bar'),
});

services.foo-bar.js

import Ember from 'ember';

export default Ember.Service.extend({
  foo: 0,
  bar: 0,
  
  fooPlus(x) {
    this.incrementProperty('foo');
    console.log('foo', this.get('foo'))
  },
  
  barPlus(x) {
    this.incrementProperty('bar');
    console.log('bar', this.get('bar'))
  }
});

templates.application.hbs

<h1>Welcome to {{appName}}</h1>
<br>
<br>
{{outlet}}
<br>
<br>

<table>
<tr>
<td>
	<h2>Foo</h2>
  {{fooBar.foo}}
  {{x-foo bump=(action fooBar.fooPlus)}}
</td>
<td>
	<h2>Bar</h2>
  {{fooBar.bar}}
  {{x-bar bump=(action fooBar.barPlus)}}
</td>
</tr>
</table>

templates.components.x-bar.hbs

{{yield}}
{{fooBar.bar}}
<button {{action bump}}>Bump</button>

templates.components.x-foo.hbs

{{yield}}
{{foo}}
<button {{action bump}}>Bump</button>

twiddle.json

{
  "version": "0.15.1",
  "EmberENV": {
    "FEATURES": {}
  },
  "options": {
    "use_pods": false,
    "enable-testing": false
  },
  "dependencies": {
    "jquery": "https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.js",
    "ember": "3.4.3",
    "ember-template-compiler": "3.4.3",
    "ember-testing": "3.4.3"
  },
  "addons": {
    "ember-data": "3.4.2"
  }
}