Adding Device Awareness to the Edge of the Network

November 20th, 2014 by

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As the balance of web traffic continues to shift toward mobile devices, operators of high-traffic websites are increasingly concerned about ensuring fast load times on these devices. Many of them are likely using content distribution networks (CDNs) to reduce latency and ensure quick- loading content. Many of these same web properties are looking at responsive design as a means to optimize content on the broadest array of devices, including mobile phones.

We’ve written before about how responsive sites tend toward excessively heavy page weights, resulting in page-load and performance issues. Our team recently investigated how we might accelerate page-load times at the edge of the network by sending device-optimized websites from a single code base.

Keep in mind that CDNs aim to push content that’s in high demand to dedicated servers at the network’s edge. Meanwhile, SNOW sits on the web server at origin to identify the client device and then intelligently serve the optimum set of images and other device-specific resources to that device. Could this be adapted for the CDN architecture, in which there are two servers involved: the origin server and the edge server?

The answer lies in special technology developed by the major CDN vendors: Edge-Side Includes (ESI). ESI is a simple markup language used to define Web page components for dynamic assembly and delivery of Web applications at the edges of the Internet. It provides a mechanism for managing content transparently across application server solutions, content management systems, and content delivery networks. The good news is that ESI is now compatible with SNOW, which means we can auto-generate ESI syntax for improved performance and device awareness for sites running on CDNs.

The new SNOW-ESI module is a great solution for device-optimized websites that leverage a CDN architecture. SNOW can be added as an optional plug-in on a desired web server, which provides direct communication with the edge server. This means we can implement all of the SNOW features at the edge of the network:

  • Device-specific user experience (our taxonomy includes thousands of PCs, smartphones, tablets, phablets, smart TVs, etc.)
  • Generation of HTML/CSS content that is optimized for the device.
  • Context-based rendering (for example for broadband vs. 3G).
  • Edge-level caching for the fastest possible performance.


SNOW-ESI offers many compelling benefits:

  1. The SNOW-ESI module delivers higher performance than that delivered by responsive techniques, improves the end-to-end performance for mobile devices by a factor of four, and reduces page-load time by as much as 25 percent.
  2. Web users, especially those with mobile devices, enjoy a fast, device-optimized website experience.
  3. For developers, there are productivity gains of 40 percent since ESI syntax is auto-generated.

We recently exhibited at the Akamai Edge conference in Miami to demonstrate SNOW-ESI to web professionals. Feedback was very positive: beyond the performance gains, attendees told us they like the easy set-up and deployment. We’ll report back once we have some specific use-cases to highlight. In the meantime, if you’d like to implement SNOW-ESI on your web architecture, please contact our team here.

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