Talk: How HTTP/2 pushes the web: An empirical study on utilization and QoE perspective on Server Push

Presented by Oliver Hohlfeld and Torsten Zimmerman

Thursday, August 17, 2017
1:30 p.m.
ICSI Lecture Hall

The simplicity of HTTP made it the default building block for desktop and mobile apps, yet it suffers from inherent inefficiencies in the modern web. HTTP/2 was designed to address these inefficiencies and its adoption remarks a major protocol shift in the Internet. Despite this relevance, its Internet-wide adoption remains unknown. Especially, the adoption and use of server push—advertised as a key feature to further reduce page load times—is completely unexplored. To answer both questions, we provide large-scale measurements of the HTTP/2 adoption and usage of server push in the wild, probing the entire IPv4 address space and the complete set of .com/.net/.org domains. We find 5.38M HTTP/2 enabled domains hosted by only few infrastructures driving this adoption. While we find the overall HTTP/2 adoption to increase, only a few hundred domains utilize server push. We examine pushed content, push strategies and identify the use of currently undocumented push strategies. Moreover, we discover large sources of overheads through server push for reoccurring page visits. By measuring page load times, we show that while push can speed up webpages, it also can slow them down—motivating the need for optimized push strategies.

In addition to the analysis based on technical metrics, it remains unknown if server push can indeed yield human perceivable improvements. Therefore, we address this open question by assessing server push in both i) a laboratory and ii) a crowdsourcing study. Our study assesses the question if server push can lead to perceivable faster PLTs as compared to HTTP/1.1 and HTTP/2 without push. We base this study on a set of 28 push-enabled real-word websites. Our results reveal that our subjects are able to perceive utilization of server push. However, its usage does not necessarily accomplish perceived PLT improvements and can sometimes even be noticeably detrimental.

Speaker Bios: 
Oliver Hohlfeld is a researcher and is heading the Network Architectures group at the Chair of Communication and Distributed systems at RWTH Aachen University. He obtained his Ph.D. from TU Berlin in 2013, advised by Anja Feldmann. His current research focuses on Internet measurements, adaptive Internet architectures, and the QoE-driven evaluation of Internet architectures and applications.

Torsten Zimmermann is a researcher and Ph.D. student at the Chair of Communication and Distributed Systems at RWTH Aachen University since 2013. He received his master degree in computer science with a minor in electrical engineering from RWTH Aachen University in April 2013. As a member of the Network Architectures group, his research interests lie in  scalable and adaptive networks, as well as in content distribution and  realization of services for constrained, opportunistic and traditional networks.