# Services

A service in Blueprint is a software component that operate in the background of the application, and outside of the [controllers](/developer-guide/routers-and-controllers/controllers.md), [routers](/developer-guide/routers-and-controllers/routers.md), and [listeners](/developer-guide/untitled.md). Services can also be references by other software components, including services themselves. For example, you could recreate a service that performs periodic background tasks, or a service that manages connections to a database.

In our example, we want to migrate the data stored in the [rental controller](/quick-start/my-first-application/controllers.md#implementing-the-action) to a service. This will allow different software entities in the Blueprint application, such as another controller, to reference the same data as the [rental controller](/quick-start/my-first-application/controllers.md#generating-your-controller).

## Defining the Service

First, lets generate the service using the Blueprint cli.

```bash
blueprint generate service rentals
```

This command will generate an empty service.

{% code title="app/services/rentals.js" %}

```javascript
const { Service, computed } = require ('@onehilltech/blueprint');

/**
 * @class rentals
 */
module.exports = Service.extend ({

});
```

{% endcode %}

The service is automatically loaded by the Blueprint application when started. 

## Implementing the Service

For the service, we need a method for adding rentals, deleting rentals, getting all the rentals, and getting a single rental. We are also going to initialize the service with the original data.

{% code title="app/services/rentals.js" %}

```javascript
const { Service, computed } = require ('@onehilltech/blueprint');

/**
 * @class rentals
 */
module.exports = Service.extend ({
  _rentals: null,

  rentals: computed ({
    get () { return this._rentals; }
  }),

  init () {
    this._super.call (this, ...arguments);

    this._rentals = [
      {
        type: 'rentals',
        id: 'grand-old-mansion',
        attributes: {
          title: 'Grand Old Mansion',
          owner: 'Veruca Salt',
          city: 'San Francisco',
          category: 'Estate',
          bedrooms: 15,
          image: 'https://upload.wikimedia.org/wikipedia/commons/c/cb/Crane_estate_(5).jpg'
        }
      },
      {
        type: 'rentals',
        id: 'urban-living',
        attributes: {
          title: 'Urban Living',
          owner: 'Mike Teavee',
          city: 'Seattle',
          category: 'Condo',
          bedrooms: 1,
          image: 'https://upload.wikimedia.org/wikipedia/commons/0/0e/Alfonso_13_Highrise_Tegucigalpa.jpg'
        }
      },
      {
        type: 'rentals',
        id: 'downtown-charm',
        attributes: {
          title: 'Downtown Charm',
          owner: 'Violet Beauregarde',
          city: 'Portland',
          category: 'Apartment',
          bedrooms: 3,
          image: 'https://upload.wikimedia.org/wikipedia/commons/f/f7/Wheeldon_Apartment_Building_-_Portland_Oregon.jpg'
        }
      }];
  },

  // get a single rental
  get (id) {
    return this._rentals.find (rental => rental.id === id);
  },

  // add a rental to the list.
  add (rental) {
    return this._rentals.push (rental);
  },

  // remove the rental from the list.
  remove (id) {
    let index = this._rentals.findIndex (rental => rental.id === id);

    if (index === -1)
      return false;

    this._rentals.splice (index, 1);
    return true;
  }
});
```

{% endcode %}

## Using the Service

Let's go back to our [`rental`](/quick-start/my-first-application/controllers.md#generating-your-controller) controller and re-implement the [`rental.get`](/quick-start/my-first-application/controllers.md#implementing-the-action) using the `rentals` service from above. To load a service into the [`rental`](/quick-start/my-first-application/controllers.md#generating-your-controller) controller, just use the [`service`](/developer-guide/services.md#accessing-a-service) computed property.

{% code title="app/controllers/rental.js" %}

```javascript
const {
  Controller,
  Action,
  service          // computed property for loading a service
} = require ('@onehilltech/blueprint');

/**
 * @class rental
 */
module.exports = Controller.extend ({
  // load the rentals service, name parameter is not needed
  rentals: service (),

  get () {
    return Action.extend ({
      execute (req, res) {
        // get the data from the rentals service
        const data = this.controller.rentals.rentals;
        res.status (200).json ({data});
      }
    })
  }
});
```

{% endcode %}

Let's break down the example above since we have made some changes to the original controller code. First, we load the service into the controller using the `service()` computed property function, which is available via the `rentals` property on the controller. Next, we updated the `get()` action implementation to retrieve the rental data from the service.

{% hint style="info" %}
All actions can access to the parent controller using the`this.controller` property.
{% endhint %}

Now, when you restart the application and open the browser to <http://localhost:5000/api/rentals>, you will get the same response as before. The only difference this time is the data is pulled from the `rentals` service, and not from local data in the controller.

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