What are HTTP Structured Fields? How do they change APIs?
Structured Fields are a new way how to define HTTP header fields. Instead of each individual field defining its own specific way how field values are represented, Structured Fields define a model that can be reused across header fields. This makes it easier to define and process header fields, because they all follow the shared model of Structured Fields.
Structured Fields, defined in RFC 8941 and published in February 2021, define a simple model of lists, dictionaries, and a few simple data types. It's a deliberately simple syntax that may not be a perfect fit for all header fields, but probably for many of them. In addition there is an ongoing effort to retrofit existing header fields as Structured Fields, so that the new processing rules and tooling can be applied to these older fields as well.
As an API developer, knowing Structured Fields at least a bit is helpful. It will allow you to use existing tooling instead of having to write your own code for parsing and serializing header field values. There already are implementations in a variety of languages, and the list of known implementations will only continue to grow.
Mark Nottingham and Poul-Henning Kamp, "Structured Field Values for HTTP", February 2021. https://www.rfc-editor.org/rfc/rfc8941
"Improving HTTP with structured header fields", https://www.fastly.com/blog/improve-h...
List of Implementations: https://github.com/httpwg/wiki/wiki/S...
Web Concepts HTTP Header Fields: https://webconcepts.info/concepts/htt...
00:00 Introduction
00:24 Where Structured Fields Come From
01:03 Web Concepts: Building Blocks for HTTP APIs
01:24 HTTP Header Fields
02:16 HTTP Header Field Examples
03:05 How to work with HTTP Header Fields
03:51 Structured Fields to the Rescue: The Future is Structured
04:30 The Structured Fields RFC
05:01 The Structured Field Design and Model
05:52 What does this mean for API designers and developers?
06:27 Brief demo of parsing
06:51 Please use a Structured Field Library
07:41 Structured Fields make it easier to "Speak HTTP"
08:15 Binary Encoding of Structured Fields
08:55 The Future is Structured
09:23 Conclusions