Mobile HTML5: Efficiency and Performance of WebSockets and Server-Sent Events

Abstract: The advent of HTML5 (Hyper Text Markup Language revision 5) technologies are re-standardizing the web and paving the way for a new breed of real-time web applications. This has great potential for mobile browsers that are now supporting protocols such as WebSocket and Server-Sent Events (SSE). These protocols can provide ecient real-time communication in a scalable manner, especially for \always-on" applications requiring persistent connections that are now widely used. Mobile devices are inherently restricted due to their limited battery power and require frequent charging. Therefore, experimentation that potentially promotes breakthroughs in mobile energy eciency is useful at this time. Extensive measurements were conducted over 3G, 4G, and WiFi networks to analyze the performance of WebSocket and SSE across a variety of popular mobile devices, browsers, and platforms. Devices were connected to a power monitor for a precise understanding of the energetic effects of keep-alive mechanisms and their overall effects on long-lasting connectivity. The results reveal that application level keep-alive mechanisms are not necessary to sustain the connections indefinitely, given proper server and network congurations. However, to avoid timeouts and to detect prematurely disconnected clients, keep-alive exchanges are necessary and useful in practice. The effects of short and long keep-alive interval values are examined in detail for all devices. Browser performance varies widely as no browser was completely successful for both WebSocket and SSE tests. Further improvements in mobile browser support for these technologies will be necessary to reach the full potential of real-time applications in the future.