Carl K. Chang

Event-based traceability for managing evolutionary change

Although the benefits of requirements traceability are widely recognized, the actual practice of maintaining a traceability scheme is not always entirely successful. The traceability infrastructure underlying a software system tends to erode over its lifetime, as time-pressured practitioners fail to consistently maintain links and update impacted artifacts each time a change occurs, even with the support of automated systems. This paper proposes a new method of traceability based upon event-notification and is applicable even in a heterogeneous and globally distributed development environment. Traceable artifacts are no longer tightly coupled but are linked through an event service, which creates an environment in which change is handled more efficiently, and artifacts and their related links are maintained in a restorable state. The method also supports enhanced project management for the process of updating and maintaining the system artifacts.

Genetic Algorithms for Project Management

The scheduling of tasks and the allocation of resource in medium to large-scale development projects is an extremely hard problem and is one of the principal challenges of project management due to its sheer complexity. As projects evolve any solutions, either optimal or near optimal, must be continuously scrutinized in order to adjust to changing conditions. Brute force exhaustive or branch-and-bound search methods cannot cope with the complexity inherent in finding satisfactory solutions to assist project managers. Most existing project management (PM) techniques, commercial PM tools, and research prototypes fall short in their computational capabilities and only provide passive project tracking and reporting aids. Project managers must make all major decisions based on their individual insights and experience, must build the project database to record such decisions and represent them as project nets, then use the tools to track progress, perform simple consistency checks, analyze the project net for critical paths, etc., and produce reports in various formats such as Gantt or Pert charts.Our research has developed a new technique based on genetic algorithms (GA) that automatically determines, using a programmable goal function, a near-optimal allocation of resources and resulting schedule that satisfies a given task structure and resource pool. We assumed that the estimated effort for each task is known a priori and can be obtained from any known estimation method such as COCOMO. Based on the results of these algorithms, the software manager will be able to assign tasks to staff in an optimal manner and predict the corresponding future status of the project, including an extensive analysis on the time-and-cost variations in the solution space. Our experiments utilized Walls GALib as the search engine. The algorithms operated on a richer, refined version of project management networks derived from Chaos seminal work on GA-based Software Project Management Net (SPMnet). Generalizing the results of Chaos solution, the new GA algorithms can operate on much more complex scheduling networks involving multiple projects. They also can deal with more realistic programmatic and organizational assumptions. The results of the GA algorithm were evaluated using exhaustive search for five test cases. In these tests our GA showed strong scalability and simplicity. Its orthogonal genetic form and modularized heuristic functions are well suited for complex conditional optimization problems, of which project management is a typical example.

WS-Net: a Petri-net based specification model for Web services

The emerging paradigm of Web services opens a new way of Web application design and development to quickly develop and deploy Web applications by integrating independently published Web services components to conduct new business transactions. As research aiming at facilitating Web services integration and verification, WS-Net is an executable architectural description language incorporating the semantics of colored Petri-net with the style and understandability of object-oriented concepts. WS-Net describes each Web services component in three layers: interface net declares the services that the component provides to other components; interconnection net specifies the services that the component acquires to accomplish its mission; and interoperation net describes the internal operational behaviors of the component. As an architectural model that formalizes the architectural topology and behaviors of each Web services component as well as the entire system, WS-Net facilitates the verification and monitoring of Web services integration.

Time-line based model for software project scheduling with genetic algorithms

Effective management of complex software projects depends on the ability to solve complex, subtle optimization problems. Most studies on software project management do not pay enough attention to difficult problems such as employee-to-task assignments, which require optimal schedules and careful use of resources. Commercial tools, such as Microsoft Project, assume that managers as users are capable of assigning tasks to employees to achieve the efficiency of resource utilization, while the project continually evolves. Our earlier work applied genetic algorithms (GAs) to these problems. This paper extends that work, introducing a new, richer model that is capable of more realistically simulating real-world situations. The new model is described along with a new GA that produces optimal or near-optimal schedules. Simulation results show that this new model enhances the ability of GA-based approaches, while providing decision support under more realistic conditions.

QoS-Based Dynamic Web Service Composition with Ant Colony Optimization

Service-oriented architecture (SOA) provides a scalable and flexible framework for service composition. Service composition algorithms play an important role in selecting services from different providers to reach desirable QoS levels according to the performance requirements of composite services, and improve customer satisfaction. This paper proposes a novel QoS-based dynamic service composition technique for web services with Ant Colony Optimization (ACO) in an optimization approach. The novelty of this work lies with our multi-objective optimal-path selection modeling for QoS-based dynamic web service composition and a new version of ACO algorithm that is proposed to solve this multi-objective optimization problem. The experiments show that the new version of ACO algorithm is very efficient in solving such a problem.

Perceptions of Technology Among Older Adults

Changes and advancements in technology have the potential to benefit older adults by promoting independence and increasing the ability to age in place. However, older adults are less likely to adopt new technology unless they see benefits to themselves. This study assessed the perceptions of 30 older adults in the Midwest concerning technology via three separate focus groups (i.e., independent apartment complex, a rural community, exercise program participants), which addressed a need in the literature (i.e., inclusion of oldest-old and rural individuals). The focus group questions included items such as what technology older adults currently used, desired improvements in technology, and the greatest challenges participants were facing or would face in the future. Overall, older adults were enthusiastic about learning new forms of technology that could help them maintain their independence and quality of life. Five themes emerged from all three focus groups: (a) Frustrations, Limitations, and Usability Concerns; (b) Transportation; (c) Help and Assistance; (d) Self-Monitoring; and (e) Gaming. The themes have important implications for future technology developed for older adults; in particular, older adults were willing and eager to adopt new technology when usefulness and usability outweighed feelings of inadequacy.

Situ: A Situation-Theoretic Approach to Context-Aware Service Evolution

Evolvability is essential for computer systems to adapt to the dynamic and changing requirements in response to instant or delayed feedback from a service environment that nowadays is becoming more and more context aware; however, current context-aware service-centric models largely lack the capability to continuously explore human intentions that often drive system evolution. To support service requirements analysis of real-world applications for services computing, this paper presents a situation-theoretic approach to human-intention-driven service evolution in context-aware service environments. In this study, we give situation a definition that is rich in semantics and useful for modeling and reasoning human intentions, whereas the definition of intention is based on the observations of situations. A novel computational framework is described that allows us to model and infer human intentions by detecting the desires of an individual as well as capturing the corresponding context values through observations. An inference process based on hidden Markov model makes instant definition of individualized services at runtime possible, and significantly, shortens service evolution cycle. We illustrate the possible applications of this framework through a smart home example aimed at supporting independent living of elderly people.

Automating speculative queries through event-based requirements traceability

Posing speculative questions about a software system is an important yet often unsupported activity. Current impact analysis techniques tend to focus upon the functionality of the system, whilst the effects of change upon performance requirements are largely ignored until after implementation. This tendency can lead to costly and time-consuming mistakes. Event-based traceability provides a robust method for handling both long-term evolutionary change as well as the short-term speculative change needed to support performance related impact analysis. By establishing dynamic links, capable of propagating data values and commands between requirements and performance models, it becomes possible to automate a wide range of speculative queries and to enhance the overall ability to predict the impact of change upon the performance of the system.

Supporting event based traceability through high-level recognition of change events

Although requirements traceability is crucial in both the development and maintenance of a software system, traceability links and related artifacts tend to deteriorate, as time-pressured practitioners fail to systematically update them in response to change. Event-based traceability addresses this issue by establishing links through a loosely coupled publisher/subscriber scheme. Dependent entities subscribe to requirements and receive event notifications as changes occur. This paper focuses upon the role played by the requirements specification as a publisher of events. A set of standard change events is defined and a method for monitoring a users actions within a requirements management environment and the subsequent recognition and publication of the change events is proposed. Early results obtained from testing this approach are reported.

Incremental Latent Semantic Indexing for Automatic Traceability Link Evolution Management

Maintaining traceability links among software artifacts is particularly important for many software engineering tasks. Even though automatic traceability link recovery tools are successful in identifying the semantic connections among software artifacts produced during software development, no existing traceability link management approach can effectively and automatically deal with software evolution. We propose a technique to automatically manage traceability link evolution and update the links in evolving software. Our novel technique, called incremental latent semantic indexing (iLSI), allows for the fast and low-cost LSI computation for the update of traceability links by analyzing the changes to software artifacts and by reusing the result from the previous LSI computation before the changes. We present our iLSI technique, and describe a complete automatic traceability link evolution management tool, TLEM, that is capable of interactively and quickly updating traceability links in the presence of evolving software artifacts. We report on our empirical evaluation with various experimental studies to assess the performance and usefulness of our approach.