Sammapun, Usa

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2003 - 20074
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  • Publication
    Formalizing Java-MaC
    (2003-07-13) Sammapun, Usa; Sharykin, Raman; DeLap, Margaret; Kim, Myong; Zdancewic, Stephan A
    The Java-MaC framework is a run-time verification system for Java programs that can be used to dynamically test and enforce safety policies. This paper presents a formal model of the Java-MaC safety properties in terms of an operational semantics for Middleweight Java, a realistic subset of full Java. This model is intended to be used as a framework for studying the correctness of Java-MaC program instrumentation, optimizations, and future experimentation with run-time monitor expressiveness. As a preliminary demonstration of this model's applicability for these tasks, the paper sketches a correctness result for a simple program instrumentation scheme.
  • Publication
    Statistical Runtime Checking of Probabilistic Properties
    (2007-03-13) Sammapun, Usa; Lee, Insup; Sokolsky, Oleg; Regehr, John
    Probabilistic correctness is an important aspect of reliable systems. A soft real-time system, for instance, may be designed to tolerate some degree of deadline misses under a threshold. Since probabilistic systems may behave differently from their probabilistic models depending on their current environments, checking the systems at runtime can provide another level of assurance for their probabilistic correctness. This paper presents a statistical runtime verification for probabilistic properties using statistical analysis. However, while this statistical analysis collects a number of execution paths as samples to check probabilistic properties within some certain error bounds, runtime verification can only produce one single sample. This paper provides a technique to produce such a number of samples and applies this methodology to check probabilistic properties in wireless sensor network applications.
  • Publication
    Run-Time Checking of Dynamic Properties
    (2005-07-12) Sokolsky, Oleg; Sammapun, Usa; Lee, Insup; Kim, Jesung
    We consider a first-order property specification language for run-time monitoring of dynamic systems. The language is based on a linear-time temporal logic and offers two kinds of quantifiers to bind free variables in a formula. One kind contains the usual first-order quantifiers that provide for replication of properties for dynamically created and destroyed objects in the system. The other kind, called attribute quantifiers, is used to check dynamically changing values within the same object. We show that expressions in this language can be eficiently checked over an execution trace of a system.
  • Publication
    RT-MaC: Runtime Monitoring and Checking of Quantitative and Probabilistic Properties
    (2005-08-17) Sammapun, Usa; Lee, Insup; Sokolsky, Oleg
    Correctness of a real-time system depends on its computation as well as its timeliness and its reliability. In recent years, researches have focused on verifying correctness of a real-time system during runtime by monitoring its execution and checking it against its formal specifications. Such verification method is called Runtime Verification. Most existing runtime verification tools verify computation correctness using qualitative property specifications but do not verify timeliness nor reliability correctness. In this paper, we investigate the verification on timeliness and reliability correctness by offering quantitative and probabilistic property specifications and implementing efficient verifiers.