In my last post, I covered some background on REST and the Richardson Maturity Model, and some emerging standards around hypermedia APIs in JSON; in particular, I outlined aspects of Hypermedia Application Language (HAL), and how it can be used to define a generic structure for JSON resources. In this post, I cover an aspect of RESTful APIs that's often overlooked: reporting problems.

He starts with some of the things around error handling and APIs that bother him and why just returning a status code representing an error isn't enough. He suggests two possible solutions to this issue - two messaging formats, API-Problem and vnd.error. He gives brief summaries of each and includes example output to give them some context.