Debugging of Web Applications with Web-TLR

TL;DR

Web-TLR is a verification tool for web applications that uses rewriting logic and model-checking, enhanced with a backward trace-slicing debugging feature to simplify counterexample analysis and improve debugging efficiency.

Contribution

The paper introduces a novel backward trace-slicing technique for Web-TLR, enabling efficient manipulation and analysis of counterexample traces in web application verification.

Findings

Trace-slicing reduces debugging effort significantly.

Simplifies analysis of complex counterexamples.

Decreases the number of verification iterations.

Abstract

Web-TLR is a Web verification engine that is based on the well-established Rewriting Logic--Maude/LTLR tandem for Web system specification and model-checking. In Web-TLR, Web applications are expressed as rewrite theories that can be formally verified by using the Maude built-in LTLR model-checker. Whenever a property is refuted, a counterexample trace is delivered that reveals an undesired, erroneous navigation sequence. Unfortunately, the analysis (or even the simple inspection) of such counterexamples may be unfeasible because of the size and complexity of the traces under examination. In this paper, we endow Web-TLR with a new Web debugging facility that supports the efficient manipulation of counterexample traces. This facility is based on a backward trace-slicing technique for rewriting logic theories that allows the pieces of information that we are interested to be traced back through inverse rewrite sequences. The slicing process drastically simplifies the computation trace by dropping useless data that do not influence the final result. By using this facility, the Web engineer can focus on the relevant fragments of the failing application, which greatly reduces the manual debugging effort and also decreases the number of iterative verifications.