Synthesis of Interface Specifications for Java Classes

While a typical software component has a clearly specified (static) interface in terms of the methods and the input/output types they support, information about the correct sequencing of method calls the client must invoke is usually undocumented. In this paper, we propose a novel solution for automatically extracting such temporal specifications for Java classes. Given a Java class, and a safety property such as the exception E should not be raised , the corresponding (dynamic) interface is the most general way of invoking the methods in the class so that the safety property is not violated. Our synthesis method first constructs a symbolic representation of the finite state-transition system obtained from the class using predicate abstraction. Constructing the interface then corresponds to solving a partial-information two-player game on this symbolic graph. We present a sound approach to solve this computationally-hard problem approximately using algorithms for learning finite automata and symbolic model checking for branching-time logics. We describe an implementation of the proposed techniques in the tool JIST- Java Interface Synthesis Tool- and demonstrate that the tool can construct interfaces accurately and efficiently for sample Java2SDK library classes

Computational Complexity of Web Service Composition Based on Behavioral Descriptions

The Web Service Composition (WSC) problem on behav-ioral descriptions deals with the automatic construction of a coordinator web service to control a set of web services to reach the goal states. As such, WSC is one of the fundamen-tal techniques to enable the Service Oriented Architecture on the Web. Despite its importance and implications, how-ever, very few studies exist on the computational complexi-ties of the WSC problem. In this paper, we present two novel theoretical findings on WSC problems: (1) Solving the WSC problem with “complete ” information is EXP-hard, and (2) Solving the WSC problem with “incomplete ” information is 2-EXP-hard. These findings imply that more efforts to de-vise efficient approximate solutions to the WSC problem be needed. 1

Formal Specifications and Analysis of the Computer Assisted Resuscitation Algorithm (CARA) Infusion Pump Control System

Reliability of medical devices such as the CARA Infusion Pump Control System is of extreme importance given that these devices are being used on patients in critical condition. The Infusion Pump Control System includes embedded processors and accompanying embedded software for monitoring as well as controlling sensors and actuators that allow the embedded systems to interact with their environments. This nature of the Infusion Pump Control System adds to the complexity of assuring the reliability of the total system. The traditional methods of developing embedded systems are inadequate for such safety-critical devices. In this paper, we study the application of formal methods to the requirements capture and analysis for the Infusion Pump Control System. Our approach consists of two phases. The first phase is to convert the informal design requirements into a set of reference specifications using a formal system, in this case EFSMs (Extended Finite State Machines). The second phase is to translate the reference specifications to the tools supporting formal analysis, such as SCR and Hermes. This allows us to conclude properties of the reference specifications. Our research goal is to develop a framework and methodology for the integrated use of formal methods in the development of embedded medical systems that require high assurance and confidence

SYNTHESIS AND COMPOSITIONAL VERIFICATION USING LANGUAGE LEARNING

Acknowledgments I would like to express my sincere gratitude toward my advisor Prof. Rajeev Alur for his support and guidance over the last six years. He has taught me almost everything for carrying out this dissertation, encouraged me to study various promising research problems, and trusted me with his generosity and patience. Without his guidance, inspiration and contribution, this dissertation would not be achieved. I am also grateful to Prof. Madhusudan Parthasarathy. He worked at UPenn as a research associate during my first three years, and I worked on my two research problems with him. His profound knowledge of game theory and controller synthesis was, without question, a great help for me to solve the problems. I thank my committee members, Prof. Insup Lee, Prof. Oleg Sokolsky, Prof. Stephanie Weirich, and Prof. Mahesh Viswanathan for their great service on my thesis. With generous effort and time, they assisted me to accomplish this dissertation. I had my first industrial experience on formal verification during my summer internship at Cadence Design Systems in New Providence, New Jersey. For the valuable opportunity, I thank Dr. Robert P. Kurshan and Dr. Xiaoqun Du. Studying at UPenn during the last six years was one of the best things in my life. Prof. Jinyoung Choi, the advisor of my master program, continuously inspired me with his kind concern. As senior Ph.D. students, Insik Shin and Yerang Hur advised me on many things about living and studying at UPenn. Finally, I am very grateful to my family, my parents Ilhyun Nam and Yongja Ryu, iii and my lovely wife Hyunyoung Kil. Sacrifice and diligence of my parents influence me as the most priceless lesson. My wife always stands by me, and cheers me up during my whole Ph.D. program. A million words cannot express my gratitude toward them enough

Type-Aware Web Service Composition Using Boolean Satisfiability Solver

The goal of the Web Service Composition (WSC) problem is to find an optimal “composition ” of web services to satisfy a given request using their syntactic and/or semantic features, when no single service satisfies it. In this paper, in particular, we study the WSC problem from semantic aspects, exploiting the supertype-subtype relationship among parameters, and propose a novel solution based on the boolean satisfiability problem (SAT). Given a set of web service descriptions and a requirement web service, we reduce the WSC problem into a reachability problem on a state-transition system, and show that the shortest path found is amount to the optimal composition. A preliminary experiment using 7 examples reveals that our proposal can find optimal compositions of web services efficiently. 1