Modern protocols
The protocols that we described previously were mostly used in an era where internet usage was not as high as it is nowadays. These days, in a lot of countries, almost everyone has a smartphone, tablet, and/or computer and uses the internet. As we are spending more and more time online, and we are using more and more different websites and applications, the need arose to combine different services into a single workflow.
For instance, let's say you are a big social media user and you have several social media accounts. You only want to publish your messages once across these different social media channels. For this to work, an application should be able to sign in to these different accounts and post content on your behalf.
This was originally implemented by the most infamous antipattern in history, known as the password-sharing antipattern, as shown in the following diagram:
Fig 4.2 – The password-sharing antipattern
Let...