HTTP Methods

Recently I have been reading “Design and Build Great Web APIs” by Mike Amundsen. And in there is a brief section about HTTP methods. Most people are probably familiar with the standard REST methods of GET, POST, PUT, and DELETE (and sometimes PATCH). I found it intriguing to learn that IANA maintains an official list of HTTP methods. Now most of these won’t be useful for every day web development as the bulk of the methods appear to be used in WebDAV and related extensions.

It is interesting to note that the methods are designated as “safe” or “idempotent” or both. A “safe” method is one that isn’t meant to modify any data. GET is categorized as “safe”, but something like POST or PUT aren’t safe as they are meant to modify data. “Idempotent” means that the method can be repeated and have the same results. So PUT is “idempotent” since you are updating something already existing, but on the other hand, POST is not “idempotent” since calling it multiple times could create multiple different things. Now all of this seems like common sense, but I believe that it was educational to learn about the meanings and intentions behind the different HTTP methods that I use daily.