Fetching and persisting data with HTTP – introducing services with Observables

So far, we have gone through a data flow where the component is our view to the outside world, but also the controller. The component uses a service to get the data, but also to persist it. The data, however, has up until this point lived in the service and that's not a very likely place for it to reside. Almost certainly, that data should be fetched and persisted to an endpoint. That endpoint is an exposed URL to a backend system published somewhere on the internet. We can use HTTP to reach said endpoint. Angular has created a wrapper on top of the vanilla way of fetching data through HTTP. The wrapper is a class that wraps the functionality of an object called   XmlHttpRequest. The Angular wrapper class is called the  HttpClient   service.