Disclosure: Improving Performance and Security of Web App Migration in Liquid Computing

Abstract

Web app migration refers to capturing a snapshot of the execution state of a web app on a device and restoring it on another device to continue its execution for cross-device liquid computing. Although web apps are relatively easy to migrate due to their high portability, there is a JavaScript language feature called closure that complicates the migration since it requires migrating the variable states of already-finished outer functions. One approach to web app migration is to instrument the source code to trace the closure variables, yet this often suffers from performance slowdown, especially for multiple migrations. In this paper, we propose a new instrumentation-based technique called Disclosure, which moves the declarations of closure variables to a managed data structure and replaces the closure variables with the corresponding references to the data structure. This technique can improve runtime performance while enhancing security. We evaluated our work with eight Octane benchmarks and four real web apps. The runtime performance penalty due to Disclosure is 0–15%, which is a significant improvement over the results of the latest instrumentation-based work that supports similar deep closures and multiple migrations to Disclosure. Furthermore, real web apps are demonstrated to migrate seamlessly, even multiple times. Finally, Disclosure can hide data from exposure during migration with a secure migration technique using data encryption.