In early web development, there was only one place to do calculations and logic work: on the server, in advance. Then javascript gained popularity and offered a second option, allowing us to utilize the end user's machine to do additional work in the browser. With Edge Side Includes (ESI), a third possibility enters the scene, namely doing region specific and independently cacheable work on servers at the edge of your content delivery network.

This session will explore the decision making process behind choosing where to do a different kinds of logic work, with a specific focus on what can be accomplished with ESI. Using real world examples from weather.com and wunderground.com's architecture, we will look at things like query string conversion to ESI, using edge bandwidth detection and ESI to deliver bandwidth-optimised Panels varients to users, and much more.

Geared mainly towards site architects and those interested in complex caching & performance planning, attendees can expect to leave this session having a much better understanding of ESI and some of the creative ways it can be used with Drupal to deliver the most performant and rich experience possible to your users.