Browserify: Empowering Consistent and Efficient Application Deployment across Heterogeneous Mobile Devices

Abstract

Nowadays, mobile devices have become an integral part of daily life. Traditionally, mobile applications are developed natively using platform-speci c programming languages and development environments. To enable a native application to run on multiple platforms is not a simple task. Usually, this would require dedicated streams of development for each platform. With the emergence of more and more mobile platforms, the e ort required to provide multi-platform support becomes strenuous. To address this problem, software engineering communities propose a cross-platform development approach. Cross-platform development enables the use of a single codebase across multiple platforms while providing acceptable application performance. This is mainly achieved using web technologies (e.g., HTML, CSS, and JavaScript) that are inherently portable from one mobile platform to another. However, existing cross-platform development frameworks are still struggling with several challenges. Firstly, they lack interoperability with commonly-used programming languages. For a long time, JavaScript was the only supported programming language by these frameworks. It is generally challenging to reuse a wide range of existing programs or libraries written in other programming languages. Secondly, most cross-platform apps run signi cantly slower than native applications. A primary culprit is the use of Javascript, which is notoriously hard to compile and optimize e ciently. The performance penalty degrades user experience and can render applications unusable on low-end devices. The recent rise of the WebAssembly has shed some light on the two challenges. WebAssembly is a young low-level programming language supported by every modern browser. WebAssembly promises to deliver signi cantly higher performance than Javascript and is designed to have high interoperability with many popular programming languages. Nevertheless, WebAssembly itself does not provide a complete solution to the challenges above. Compared to native applications, WebAssembly applications have been reported on average to run 45% slower according to previous benchmarks. Besides that, many existing programs can not be directly reused since they expect abstractions from modern OSs such as threads, le system, and sockets. It is important to note that these abstractions are not directly available in WebAssembly. In this thesis, we present Browserify, a framework that enables consistent and performant application deployment across heterogeneous mobile devices. Browserify consists of two major components: BroswerVM and Wasmachine. BrowserVM is a WebAssembly-based virtual machine hypervisor that allows the execution of unmodi ed and complete operating systems and applications inside browsers. Though slower than native hypervisors, BroswerVM provides acceptable performance to reuse unmodi ed applications that are not computeintensive. Wasmachine is an OS aiming to e ciently and securely execute WebAssembly applications in mobile devices with constrained resources. Wasmachine achieves e cient execution by compiling WebAssembly ahead of time to native binary and executing it in kernel mode for zero-cost system calls. In practice, WebAssembly applications in Wasmachine can even run faster than their native counterparts in Linux. We illustrate the capabilities of Browserify via a case study called SwiftPad. In SwiftPad, we port the famous TEX typesetting system to e-paper mobile devices and enable users to compose high typographic quality documents in a WYSIWYG (what you see is what you get) fashion. We showcase how Browserify facilitates building cross-platform applications and the reuse of existing software components.