Chin-Yun Hsieh

Exception handling refactorings: Directed by goals and driven by bug fixing

Exception handling design can improve robustness, which is an important quality attribute of software. However, exception handling design remains one of the less understood and considered parts in software development. In addition, like most software design problems, even if developers are requested to design with exception handling beforehand, it is very difficult to get the right design at the first shot. Therefore, improving exception handling design after software is constructed is necessary. This paper applies refactoring to incrementally improve exception handling design. We first establish four exception handling goals to stage the refactoring actions. Next, we introduce exception handling smells that hinder the achievement of the goals and propose exception handling refactorings to eliminate the smells. We suggest exception handling refactoring is best driven by bug fixing because it provides measurable quality improvement results that explicitly reveal the benefits of refactoring. We conduct a case study with the proposed refactorings on a real world banking application and provide a cost-effectiveness analysis. The result shows that our approach can effectively improve exception handling design, enhance software robustness, and save maintenance cost. Our approach simplifies the process of applying big exception handling refactoring by dividing the process into clearly defined intermediate milestones that are easily exercised and verified. The approach can be applied in general software development and in legacy system maintenance.

Watermarking MPEG-4 2D Mesh Animation in Multiresolution Analysis

Although watermarking techniques have been successfully applied to natural images and videos, little progress is made in the area of graphics animation. In particular, the MPEG-4 dynamic 2D mesh that provides efficient coding for animated graphics data imposes several realistic constraints for watermarking. In this paper, we propose a robust watermarking technique for MPEG-4 2D mesh animation. A multiresolution analysis is applied to locate feature motions of the animated mesh. The watermark signal is inserted based on a spread-spectrum approach by perturbing the extracted feature motions. We have also incorporated a spatial-domain registration technique to restore geometrically transformed mesh data. A variety of attacks, including the affine transformation, smoothing, enhancement and attenuation, and random noise, are used to verify the robustness of the proposed system. Experimental results show that our watermarks can withstand the aforementioned attacks. We also compare the performance of several common integer-to-integer wavelet transforms under the proposed framework.

Test-duo: a framework for generating and executing automated acceptance tests from use cases

The Test-Duo framework for generating and executing acceptance tests from use cases is presented. In Test-Duo, annotations are added to use cases to explicate system behaviors. ROBOT framework compatible test cases are then generated and applied to test the system under a search regime. Tool support is discussed.

Contract Specification in Java: Classification, Characterization, and a New Marker Method

Design by Contract (DBC), originated in the Eiffel programming language, is generally accepted as a practical method for building reliable software. Currently, however, few languages have built-in support for it. In recent years, several methods have been proposed to support DBC in Java. We compare eleven DBC tools for Java by analyzing their impact on the developers programming activities, which are characterized by seven quality attributes identified in this paper. It is shown that each of the existing tools fails to achieve some of the quality attributes. This motivates us to develop ezContract, an open source DBC tool for Java that achieves all of the seven quality attributes. ezContract achieves streamlined integration with the working environment. Notably, standard Java language is used and advanced IDE features that work for standard Java programs can also work for the contract-enabled programs. Such features include incremental compilation, automatic refactoring, and code assist.

ezContract: Using Marker Library and Bytecode Instrumentation to Support Design by Contract in Java

Several approaches have been proposed to support Design by Contract in Java. In this paper, through the use of markers which are predefined dummy methods and attributes, a new approach to annotate contracts is presented. The annotated programs can be directly compiled by standard Java compilers. A bytecode instrumentor is developed to manipulate the bytecode to inject contract evaluation instructions and make the contracts executable at runtime. The marker approach avoids two primary problems found in the existing practices: source compatibility that depends on language extension and symbolic barrier that leaves contracts and their targets unrelated. It also facilitates streamlined integration with IDEs and improves readability as well as writability of the contract- annotated programs.

Emerging patterns of continuous integration for cross-platform software development

This paper proposes a collection of continuous integration patterns for use in developing cross-platform software. The patterns reflect our experience in building commercial and open-source cross-platform software which made extensive use of continuous integration systems. We focus on the patterns that represent the basic types of projects to be put on a continuous integration system to produce cross-platform software. An example is given in the pattern language form to illustrate the use of these patterns. By putting these patterns in a pattern language, insights on the relationships among these patterns become apparent. By applying the patterns in this pattern language, continuous integration can be made to support the development of cross-platform software better.

A method for web application data migration based on RESTful API: A case study of ezScrum

As a web application evolves, it tends to adopt a mixture of different ways of storing persistent data. This often discourages users from upgrading from an older version to a newer version if the data schemas are different. To tackle this problem, we have developed a RESTful API-based data migration method for embedding ETL (extract-translate-load) features into web applications. The proposed RESTful API-based method has been applied to migrating data for ezScrum, a web application for Scrum support.

Expressing Requirements of Spot Services in Problem Frames: Design Domains as Physical-Lexical Domains

An extension to the design domain of problem frames has been proposed. The proposed extension is intended to cope with the inclusion of lexical design domains that have physical counterparts with the equivalent information. An example of the use of such a physical counterpart is illustrated with a spot service application in patient monitoring.

Delivering Specification-Based Learning Processes with Service-Oriented Architecture: A Process Translation Approach

Department of Computer Science and Information Engineering National Taipei University of Technology Taipei, 106 Taiwan Service-oriented architecture (SOA) is increasingly popular for constructing eLearning systems. SOA encourages the separation of process from underlying services. The separation is also advocated by IMS Learning Design, an international standard for describing a learning process. Despite the apparent congruence and the recent proposals of several SOAs for eLearning, existing eLearning systems have yet to take full advantage of the process-service separation and are denied of a number of quality attributes promised. In this paper, we describe a new approach, which incorporates process translation and a three-layer SOA, for delivering specification-based eLearning processes. Specially, an eLearning course description specified in IMS Learning Design is translated into a process of Business Process Execution Language (BPEL). The translated BPEL process is then executed on a BPEL engine, which powers the process service layer of the SOA and keeps the learning processes separated from the underlying Web services. The architecture achieves extensibility, reusability, and ease of integration by allowing advanced eLearning standards to be incrementally implemented as a group of collaborating processes in BPEL. Translation rules from IMS Learning Design into BPEL are presented. The benefits of the proposed approach are investigated and compared with existing eLearning architectures.

Watermarking MPEG-4 2D mesh animation with time-series analysis

Former watermarking techniques have been largely developed for application to natural videos. Important applications, including virtual reality, computer games, cartoons, and movies, involve another category of visual data: computer animation. In this study, we developed robust watermarking techniques to protect MPEG-4 2D mesh animation against copyright infringement. Three time-series analysis tools, the discrete cosine transform (DCT), singular spectrum analysis (SSA), and discrete wavelet transform (DWT), are employed to analyze the motion characteristics of mesh animation. The watermark is cast upon the important motion components by employing the spread-spectrum principle. During watermark extraction, a spatial-domain least-squares registration technique is used to restore the distorted mesh. Each watermark bit is then detected by a hard decision with the aid of cryptographically secure keys. We have tested the proposed system against a variety of attacks, including affine transformations, temporal smoothing, spectral enhancement and attenuation, and additive random noise. The time-series analysis tools studied here are evaluated in terms of their robustness to attacks and the required computational complexity.