And now for something Vary different
Most people working with CDN caches know about the Vary header, but few properly understand what it really does. And with the advent of the Key header, new patterns for varying cache content will emerge. Andrew Betts shares common and advanced use cases for Vary, such as language, A/B testing, compression, and service worker support, and outlines potential changes to consider when Key arrives.
| Talk Title | And now for something Vary different |
| Speakers | Andrew Betts (Fastly) |
| Conference | O’Reilly Velocity Conference |
| Conf Tag | Build Resilient Distributed Systems |
| Location | London, United Kingdom |
| Date | October 18-20, 2017 |
| URL | Talk Page |
| Slides | Talk Slides |
| Video | |
The Vary header has long been a vital tool for website owners to make content cacheable even if it changes based on inputs other than the URL. The problem is this tool is typically either severely underused, usually limited to Accept-Encoding variation, or is used very badly, resulting in a complete destruction of the cache potential of the page. Now the IETF is bringing forward a new standard, Key, which aims to provide a more powerful replacement for Vary. Andrew Betts examines the common misconceptions about Vary, the resulting common misconfigurations and how to fix them, advanced use cases for Vary that vastly increase the efficiency of content distribution, and the changes Key will bring about. Along the way, Andrew also considers whether Key actually fails to cater for some of the current use cases for Vary.
