William C. Chu

A quantitative approach for evaluating the quality of design patterns

In recent years, the influence of design patterns on software quality has attracted an increasing attention in the area of software engineering, as design patterns encapsulate valuable knowledge to resolve design problems, and more importantly to improve design quality. As the paradigm continues to increase in popularity, a systematic and objective approach to verify the design of a pattern is increasingly important. The intent session in a design pattern indicates the problem the design pattern wants to resolve, and the solution session describes the structural model for the problem. When the problem in the intent is a quality problem, the structure model should provide a solution to improve the relevant quality. In this work we provide an approach, based on object-oriented quality model, to validate if a design pattern is well-designed, i.e., it answers the question of the proposed structural model really resolves the quality problems described in the intent. We propose a validation approach to help pattern developers check if a design pattern is well-designed. In addition, a quantitative method is proposed to measure the effectiveness of the quality improvement of a design pattern that pattern users can determine which design patterns are applicable to meet their functional and quality requirements.

A new approach to verify rule-based systems using petri nets

Abstract In the past several years, various graphical techniques were proposed to analyze various types of structural errors, including inconsistency (conflict rules), incompleteness (missing rules), redundancy (redundant rules), and circularity (circular depending rules), in rule-based systems in which rules can be represented in propositional logic. In this paper, we present a special reachability graph technique based on ω-nets (a special type of low-level petri nets) to detect all of the above types of structural errors. Our new technique is simple, efficient, and can be easily automated. We highlight the unique features of this new approach and demonstrate its application through two examples.

Applying dynamic fuzzy Petri Net to web learning system

This investigation presents a DFPN (Dynamic Fuzzy Petri Net) model to increase the flexibility of the tutoring agents behaviour and thus provide a learning content structure for a lecture course. The tutoring agent is a software assistant for a single user, who may be an expert in an e-Learning course. Based on each learners behaviour, the tutoring agent derives a different learning content structure, and then maps it onto a SCORM activity tree structure. SCORM is the most widely accepted standard e-Learning application. However, it is too complex to enable the lecturers to apply SCORM Sequencing and Navigation in developing a course. Accordingly, this investigation applies DFPN to provide a graphical editing interface, to enable the tutoring agent to help each learner reach his (or her) learning target.

An orthogonal simulated annealing algorithm for large floorplanning problems

The conventional simulated annealing with some random generation mechanism using the sequence-pair topological representation in block placement and floorplanning is effective for a very small number of modules (40-50). This paper proposes an orthogonal simulated annealing algorithm (OSA) with an efficient generation mechanism (EGM) for solving large floorplanning problems. EGM samples a small number of representative floorplans and then efficiently derives a high-performance floorplan by using a systematic reasoning method for the next move of OSA based on orthogonal experimental design. Furthermore, an improved swap operation is proposed which cooperates with EGM to make OSA efficient. Excellent experimental results using the Microelectronics Center of North Carolina and the Gigascale Systems Research Center benchmarks show that OSA performs better than existing methods for large floorplanning problems.

An object-oriented architecture supporting Web application testing

The flexibility and rich application frameworks of the Web model make Web applications more prevalent in both Internet and intranet environments. Programmers enjoy various Web application frameworks with support ranging from simple user interactions based on the plain client-server model, to complicated distributed-object computations based on CORBA. The variety gives users the flexibility to decide a proper framework, and leads to demands for new support tools and a testing framework to test and maintain Web applications. This paper presents an architecture containing several supporting tools which enhance traditional software testing architecture to fit common Web application frameworks. The architecture suits current Web models and reuses several software patterns and architectures from traditional testing environments. In addition, a prototype Web application testing environment is constructed for demonstration.

Extracting entity-relationship diagram from a table-based legacy database

Current database reverse engineering researches presume that the information regarding semantics of attributes, primary keys, and foreign keys in database tables is complete. However, this may not be the case. In this paper, we present a process that extracts an extended entity relationship diagram from a table-based database with little descriptions for the fields in its tables and no description for keys. The primary inputs of our approach are system display forms and table schema. An extended ER diagram is successfully extracted in a case study.

A complexity measure for ontology based on UML

UML is a good tool to represent ontologies. When using UML for ontology development, one of the principal goals is to assure the quality of ontologies. UML class diagrams provide a static modeling capability that is well suited for representing ontologies, so the structural complexity of a UML class diagram is one of the most important measures to evaluate the quality of the ontologies. This paper uses weighted class dependence graphs to represent given class diagrams, and then presents a structure complexity measure for the UML class diagrams based on entropy distance. It considers complexity of both classes and relationships between the classes, and presents rules for transforming complexity value of classes and different kinds of relations into weighted class dependence graphs. This method can measure the structure complexity of class diagrams objectively.

Agent-based Web services evolution for pervasive computing

Pervasive computing will be a fertile source of challenging research problems in computer systems for many years to come. The ability to obtain services and information from an environment anywhere at anytime is part of pervasive computing. The problem is that most of existing services and applications are designed for stationary PCs. How to evolve these so called legacy system towards those mobile users in a controlled manner is vital for that pervasive computing can become more widespread. In this paper, we report our efforts on the PerEvo project. After discussing the basic features and challenges of pervasive computing, we present an agent-based Web services evolution approach, which is well suited to building software solutions for pervasive computing, and illustrate our solutions through a booking scenario.

Green Power Management with Dynamic Resource Allocation for Cloud Virtual Machines

With the development of electronics in governments and business, the implementation of these services are increasing demand for servers. Continued expansion of servers represents our need for more space, power, air conditioning, network, human resources and other infrastructure. Regardless of how powerful servers now become, we do not make good use of all resources and strive for the waste. In this paper, the Green Power Management (GPM) is proposed for load balancing for virtual machine management on cloud. It includes three main phrases: (1) supporting green power mechanism, (2) implementing virtual machine resource monitor onto Open Nebula with web-based interface, and (3) integrating a Dynamic Resource Allocation (DRA) and Open Nebula functions as bases instead of traditionally booting physical machines with command mode.

Extracting Reusable Object-Oriented Legacy Code Segments with Combined Formal Concept Analysis and Slicing Techniques for Service Integration

Web services, together with service-oriented architectures, are promising integration technology to facilitate legacy system Webification and evolution. However, a service-oriented re-engineering process is still essential for legacy systems to survive in the service-oriented computing environment. In this service-oriented re-engineering process, understanding and reusing object-oriented code turn to be important activities. In this paper, we proposed a comprehensive approach to support the extraction and integration of reusable object-oriented legacy code. In the extraction phase, formal concept analysis, which is a general and flexible technique for recovering structural design information, and inter-procedural program slicing are adopted as main reverse engineering techniques to recover reusable object-oriented code. In the integration phase, service packaging processes are presented in details. Our approach produces extracted components with core legacy object-oriented code function in Web services by wrapping underlying computing models with XML