Once deployed in production, an application is exposed to a large number of requests. Inevitably, some of them will be malicious. This implicitly brings the requirement of granting explicit access permissions. That is, authenticating a selected number of consumers to have access to your service. Most of the consumers will use the service only for data provisioning. However, a few will need to be able to provide new, or modify the existing, contacts data. In order to ensure that only appropriate consumers will be able to execute POST, PUT, and DELETE requests, we will have to introduce the concept of authorization into our application, which will grant only explicitly selected users modification permissions.
As the contact data service may provide sensitive private information, such as phone numbers, e-mail addresses, and so on, the HTTP protocol, being a text protocol, may not be secure enough. The information transmitted through it is subject to man-in...