Moving Edge-Side Includes to the Real Edge—the Clients
Edge-Side Includes (ESI) is an open mark-up lan-guage that allows content providers to break their pages into fragments with individual caching characteristics. A page is reassembled from ESI fragments by a content delivery network (CDN) at an edge server, which selectively downloads from the origin content server only those fragments that are necessary (as opposed to the entire page). This is expected to reduce the load and bandwidth requirements of the content server.
This paper proposes an ESI-compliant approach in which page reconstruction occurs at the browser rather than the CDN. Unlike page assembly at the network edge, CSI optimizes content delivery over the last mile, which is where the true bottleneck often is. We call the client-based approach Client-Side Includes, or CSI.