Page History
In our What is REST? article we focused on a few of the important constraints of REST that are relevant to the SRP HTTP Framework. When discussing the Uniform Interface constraint, we provided an introduction to the concept of Hypermedia As The Engine Of Application State (or HATEOAS for short). In our summary of the concept of HATEOAS, we emphasized its importance but suggested the reader visit this present page to understand why HATEOAS is important.
| Table of Contents |
|---|
Quick Answer
This Wikipedia article on HATEOAS nicely summarizes some key objectives and benefits of HATEOAS, so we will cite these here (the emphasis in the below citations are ours):
...
Let's revisit the GET /orders/1234 API again. It was previously suggested that the resource might include a link to cancel the order. In order for HATEOAS to work as intended, the server needed to verify that order #1234 was capable of being cancelled. This could rely on a number of factors, such as permissions of the user, whether the product was already shipped, or terms and conditions of this order. In any caseall cases, the server makes a determination and returns or withhold withholds the link (hypermedia) that informs the client that this order may be cancelled. Furthermore, the client must use this link to request a state change (i.e., cancel the order)order cancellation link as needed.
In Summary
HATEOAS is an important design element of APIs that contributes to the uniform interface constraint of REST. However, HATEOAS will be underutilized if clients aren't programmed to expect and utilize hypermedia content. In these cases, RESTful APIs are not much more than ways to access static resource content. Therefore, in order for HATEOAS to be worthwhile, both clients and servers need to support hypermedia content and use it request changes in the resource state.
