Byeong-Mo Chang

Interprocedural exception analysis for Java

Current JDK Java compiler relies too much on programmer’s specification for checking against uncaught exceptions of the input program. It is not elaborate enough to remove programmer’s unnecessary handlers (when programmer’s specifications are too many) nor suggest to programmers for specialized handlings (when programmer’s specifications are too general). We propose a static analysis of Java programs that estimates their exception flows independently of the programmer’s specifications. This analysis is designed and implemented based on set-constraint framework. Its cost-effectiveness is suggested by sparsely analyzing the program at method-level (hence reducing the number of unknowns in the flow equations). We have shown that our exception analysis can effectively detect uncaught exceptions for realistic Java programs.

An uncaught exception analysis for Java

Current JDK Java compiler relies on programmers declarations (by throws clauses) for checking against uncaught exceptions of the input program. It is not elaborate enough to remove programmers unnecessary handlers nor suggest to programmers for specialized handlings (when programmers declarations are too broad). We propose a static analysis of Java programs that estimates their uncaught exceptions independently of the programmers declarations. This analysis is designed and implemented based on set-based framework. Its cost-effectiveness is suggested by sparsely analyzing the program at method level (hence reducing the number of unknowns in the flow equations). We have shown that our interprocedural exception analysis is more precise than JDK-style intraprocedural analysis, and also that our analysis can effectively detect uncaught exceptions for realistic Java programs.

A Context-Aware Smart Tourist Guide Application for an Old Palace

The goal of our research is to develop a smart context-aware self guided tour assistant as a context- aware real world application. As a context-aware tourist guide application, we have been developing a PDA-based location-aware tourist guide application for the old palace Deoksugung in the center of Seoul. It will guide visitors to the palace with information about: current location, attractions nearby, and details about specific buildings. Rich multimedia support has been incorporated into the system to provide extra features to enhance the self-guided tour.

Constructing Control Flow Graph for Java by Decoupling Exception Flow from Normal Flow

A control flow graph represents all the flows of control that may arise during program execution. Since exception mechanism in Java induces flows of control, exception induced control flow have to be incorporated in control flow graph. In the previous research to construct control flow graph, they compute exception flow and normal flow at the same time while computing control flow information. In this paper, we propose a method to construct control flow graph by computing separately normal flow and exception flow. We show that normal flow and exception flow can be safely decoupled, hence these two flows can be computed separately. We propose the analysis that estimates exception-induced control flow, and also propose exception flow graph that represents exception induced control flows. We show that a control flow graph can be constructed by merging an exception flow graph onto a normal flow graph.

Static check analysis for Java stack inspection

Most static analysis techniques for optimizing stack inspection approximate permission sets such as granted permissions and denied permissions. Because they compute permission sets following control flow, they usually take intra-procedural control flow into consideration as well as call relationship. In this paper, we observed that it is necessary for more precise optimization on stack inspection to compute more specific information on checks instead of permissions. We propose a backward static analysis based on simple call graph to approximate redundant permission checks which must fail. In a similar way, we also propose a backward static analysis to approximate success permission checks, which must pass stack inspection.

A policy description language for context-based access control and adaptation in ubiquitous environment

The goal of our research is to provide an advanced programming environment for ubiquitous computing, which facilitates the development of secure and reliable ubiquitous software. The environment consists of a high-level ubiquitous programming framework, a run-time system enhanced with better context adaptation and security, and programming support tools. In this paper, we focus on a ubiquitous programming framework, which includes a high-level policy description language, a translator to Java and a runtime system. We first present a high-level policy description language for formally specifying context entity relation, as well as context-based access control and adaptation policies. We then describe how a specification in the policy description language can be translated into Java code which makes use of JCAF.

A thread monitoring system for multithreaded Java programs

To assist developing robust multithreaded software, we develop a thread monitoring system for multithreaded Java programs, which can trace or monitor running threads and synchronization. We design a monitoring system which has options to select interesting threads and synchronized actions. Using this tool, programmers can monitor only interesting threads and synchronization in more details by selecting options, and can detect a deadlock. It also provides profile information after execution, which summarizes behavior of running threads and synchronized actions during execution. We implement the system based on code inlining, and presents some experimental results.

A type and effect system for activation flow of components in Android programs

This paper proposes a type and effect system for analyzing activation flow between components through intents in Android programs. The activation flow information is necessary for all Android analyses such as a secure information flow analysis for Android programs. We first design a formal semantics for a core of featherweight Android/Java, which can address interaction between components through intents. Based on the formal semantics, we design a type and effect system for analyzing activation flow between components and demonstrate the soundness of the system.

A programming environment for ubiquitous computing environment

The goal of this research is to provide an advanced programming environment for ubiquitous computing, which facilitates the development of secure and reliable ubiquitous software. A discussion follows on the design and implementation of a ubiquitous programming framework, which is based on high-level policy description language. A context-based access control manager(CACM) was implemented for context-aware access control, while an adaptation engine was integrated for context adaptation in dynamically changing environments. A simulator was also implemented for conducting experiments with this framework for ubiquitous applications.

A review on exception analysis

Context: Exception handling has become popular in most major programming languages, including Ada, C++, Java, and ML. Since exception handling was introduced in programming languages, there have been various kinds of exception analyses, which analyze exceptional behavior of programs statically or dynamically. Exception analyses have also been applied to various software engineering tasks such as testing, slicing, verification and visualization.Objective: This paper aims at providing a comprehensive view of studies on exception analysis. We conducted a review on exception analysis to identify and classify the studies.Method: We referred to the literature review method, and selected a comprehensive set of 87 papers on exception analysis from 515 papers published in journals and conference proceedings. The categorization and classification were done according to the research questions regarding to when they analyze, what they analyze, how to analyze, and applications of exception analysis.Results: We first identify three categories of static exception analysis and two categories of dynamic exception analysis together with the main applications of the exception analyses. We also discuss the main concepts, research methods used and major contributions of the studies on exception analysis.Conclusion: We have provided the comprehensive review of exception analysis. To the best of our knowledge, this is the first comprehensive review on exception analysis. As a further work, it would be interesting to see how the existing exception analysis techniques reviewed in this paper can be applied to other programming languages with exception handling mechanism, such as C#, Scala, and Eiffel, which have been rarely explored.