Systematic Analysis of Web Browser Caches

Abstract

The caching of frequently requested web resources is an integral part of the web ever since. Cacheability is the main pillar for the web's scalability and an important mechanism for optimizing resource consumption and performance. Caches exist in many variations and locations on the path between web client and server with the browser cache being ubiquitous to date. Web developers need to have a profound understanding of the concepts and policies of web caching even when exploiting these advantages is not relevant. Neglecting web caching may otherwise result in more serve consequences than the simple loss of scalability and efficiency. Recent misuse of web caching systems shows to affect the application's behavior as well as privacy and security. In this paper we introduce a tool-based approach to disburden web developers while keeping them informed about caching influences. Our first contribution is a structured test suite containing 397 web caching test cases. In order to make this collection easily adoptable we introduce an automated testing tool for executing the test cases against web browsers. Based on the developed testing tool we conduct a systematic analysis on the behavior of web browser caches and their compliance with relevant caching standards. Our findings on desktop and mobile versions of Chrome, Firefox, Safari and Edge show many diversities as well as discrepancies. Appropriate tooling supports web developers in uncovering such adversities. As our baseline of test cases is specified using a specification language that enables extensibility, developers as well as administrators and researchers can systematically add and empirically explore caching properties of interest even in non-browser scenarios.