We present the S4R supplemental routing system to address the constraints BGP places on ISPs and stub network alike. Technical soundness and economic viability are equal first class design requirements for S4R. In S4R, ISPs announce links connecting different parts of the Internet. ISPs can selfishly price their links to attract maximal amount of traffic. Stub networks can selfishly select paths that best meet their requirements at the lowest cost. We design a variety of practical algorithms for ISP and stub network response that strike a balance between accommodating selfishness of all participants and ensuring efficient and stable operation overall. We employ large scale simulations over realistic scenarios to show that S4R operates at a close-to-optimal state and that it encourages broad participation from stubs and ISPs.

Software developers need automated techniques to maintain the correctness of complex, evolving Web applications. While there has been success in automating some of the testing process for this domain, there exists little automated support for verifying that the executed test cases produce expected results. We assist in this tedious task by presenting a suite of automated oracle comparators for testing Web applications. To effectively identify failures, each comparator is specialized to particular characteristics of the possibly nondeterministic Web applications' output in the form of HTML responses. We also describe combinations of comparators designed to achieve both high precision and recall in failure detection and a tool for helping testers to analyze the output of multiple oracles in detail. We present results from an evaluation of the effectiveness and costs of the oracle comparators. We also provide recommendations to testers on applying effective oracle comparators based on their application's characteristics.