Prof. Dr. Wolfram Wingerath


Claudia Martsfeld


Arbeitsgruppe Data Science
Universität Oldenburg
Fakultät II – Department für Informatik
Escherweg 2, 26121 Oldenburg, Germany


ICWE 2022: 2 Papers on Cross-Entity Delta Encoding (Research) and Benchmarking Compression Algorithms for the Web (Demo)

Rejoice! Both of our ICWE 2022 submissions on efficient Web compression (research paper and demo paper) have been accepted for publication!

Rejoice! Both of our ICWE 2022 submissions on efficient Web compression (research paper and demo paper) have been accepted for publication!

Research Paper

The preprint is available here.


Delta encoding and shared dictionary compression (SDC) for accelerating Web content have been studied extensively in research over the last two decades, but have only found limited adoption in the industry so far: Compression approaches that use a custom-tailored dictionary per website have all failed in practice due to lacking browser support and high overall complexity. General-purpose SDC approaches such as Brotli reduce complexity by shipping the same dictionary for all use cases, while most delta encoding approaches just consider similarities between versions of the same entity (but not between diff erent entities). In this study, we investigate how much of the potential benefi ts of SDC and delta encoding are left on the table by these two simplifi cations. As our fi rst contribution, we describe the idea of cross-entity delta encoding that uses cached assets from the immediate browser history for content encoding instead of a precompiled shared dictionary: This avoids the need to create a custom dictionary, but enables highly customized and efficient compression. Second, we present an experimental evaluation of compression efficiency to hold cross-entity delta encoding against state-of-the-art Web compression algorithms. We consciously compare algorithms some of which are not yet available in browsers to understand their potential value before investing resources to build them. Our results indicate that cross-entity delta encoding is over 50% more efficient for text-based resources than compression industry standards. We hope our fi ndings motivate further research and development on this topic.

Demo Paper

The preprint is available here.


In this demonstration, we present Compaz, an extensible benchmarking tool for web compression that enables evaluating approaches before they have been fully implemented and deployed. Compaz makes this possible by collecting all relevant data from user journeys on live websites fi rst and then performing the benchmark analysis as a subsequent step with global knowledge of all transmitted resources. In our demonstration scenario, the audience can witness how current websites could improve their compression ratio and save bandwidth. They can choose from standard and widespread approaches such as Brotli or gzip and advanced approaches like shared dictionary compression that are currently not even supported by any browser.

(Stand: 16.03.2023)  |