As you can see, it’s: Get, Update, Delete, Add, etc. I think, it would be more honestly to start learning right from more often methods. Fortunately, they are sorted in complexity ascending order. So in the same way we’ll learn them.
Communication with the Vault server takes the form of SOAP commands over HTTP. You can check this, watching client-server dialog with Web Debugging Proxy, like Fiddler. We can imitate this executing PowerShell code that gets all groups.
And watch the dialog between client and server with Fiddler
LinksHow to think about web services APIs – REST and SOAP
File Transfer as Binary Data