Edge-Side-Includes with Cloudflare Workers

The text discusses the concept of Edge-Side-Includes (ESI) at Cloudflare, which is an XML markup language that can be inserted in HTML or other text-based contents to define how interstitial proxies/CDNs need to combine static and dynamic portions. It also explains how ESI can be implemented using Cloudflare Workers, a serverless framework for implementing custom logic directly within the Edge. The author provides an example of a worker script that fetches a globally static page with some dynamic fragment and merges them before sending the final webpage to visitors. Testing results show that the page is served from cache but modified by the worker due to the detected ESI block.