# chap 4

## Rails: ActiveModel, ActiveRecord and ActiveResource

```
ActiveModel + Database Support = ActiveRecord

ActiveModel via WebService API = AcitveResource
```

**ActiveModel**: all the model related without db. (Ex: validations).

**ActiveRecord**: associates a class to the database. (Ex: find method).

**ActiveResource**: Similar to ActiveRecord. However, instead of being backed by a database, an ActiveResource object is backed by another application through a web service API.

## Rails: Action Pack

```
Action Pack: From request to response -> provides the view and controller layers.
|
|- Action Dispatch: parses request, handles routing, cookies and sessions.
|- Action Controller
```


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