I often get asked the question, “What is the difference between REST and RESTFul?” First off, let’s keep in mind that many words in technology are used inconsistently or change meaning in specific contexts. Sometimes when people say REST often they actually mean RESTFul. Both terms refer to a software architectural style of Application Programming Interface (API) development.

REST stands for “Representational State Transfer” and was coined in 2000 by Roy Fielding while working on his PhD at UC Irvine. The key notion is that the HTTP verbs, “POST”, “GET”, “PUT”, and “DELETE” can be used like the database operations “Create”, “Read”, “Update”, and “Delete”. These database operations are often referred to as CRUD. So in pure REST, there is a one to one match as outlined below.

  • POST: Create
  • GET: Read
  • PUT: Update
  • DELETE: Delete

RESTFul is a slightly more relaxed version of the same general software architectural style. For example, we might choose not to use PUT or DELETE at all and instead use POST or GET in some manner to achieve the same update and delete functions. Many APIs out there work in this way since it’s often simpler and more practical.

REST/RESTFul approaches are not new, but they are an increasingly popular pattern for exposing machine-to-machine interfaces, i.e. APIs. REST/RESTful approaches are popular in part because they are technology agnostic in the sense that usually they can be implemented in any programming language and on a variety of HTTP (Web) servers. Also, REST/RESTFul servers and clients are easier to implement than SOAP architectures since, unlike the latter, they don’t require WebLogic, WebSphere, or similar heavy (and often expensive) software tools to implement.