Automatic workarounds for web applications

We present a technique that finds and executes workarounds for faulty Web applications automatically and at runtime. Automatic workarounds exploit the inherent redundancy of Web applications, whereby a functionality of the application can be obtained through different sequences of invocations of Web APIs. In general, runtime workarounds are applied in response to a failure, and require that the application re-main in a consistent state before and after the execution of a workaround. Therefore, they are ideally suited for inter-active Web applications, since those allow the user to act as a failure detector with minimal effort, and also either use read-only state or manage their state through a trans-actional data store. In this paper we focus on faults found in the access libraries of widely used Web applications such as Google Maps. We start by classifying a number of re-ported faults of the Google Maps and YouTube APIs that have known workarounds. From those we derive a number of general and API-specific program-rewriting rules, which we then apply to other faults for which no workaround is known. Our experiments show that workarounds can be readily de-ployed within Web applications, through a simple client-side plug-in, and that program-rewriting rules derived from ele-mentary properties of a common library can be effective in finding valid and previously unknown workarounds.