The Recipe for Angular 2 in a Java EE Environment: Frontend 2

This is the fourth article in our “The Recipe for Angular 2 in a Java EE Environment" series, with a more detailed description of the Frontend of the Angular2 and JavaEE Project. It follows my third article about Angular 2 and Java EE that gave a detailed overview of the Frontend infrastructure of the Car Rental Project.
In this article about the Angular UI, we’ll go over the HTTP Service with its Types, the Detailview with its Validations, and 2 Tests, which are shown.