Conceptual models of software artifacts

According to constructivism, learning takes place by constructing cognitive structures based upon current, perhaps naive, knowledge and new experiences. In the case of software artifacts like programming languages and applications, current knowledge is not a solid base upon which to build viable new knowledge. Therefore, we conjecture that explicit conceptual models constructed by educators should be able to improve the performance of users in their interaction with software artifacts, in our case the popular word processor MS-Word. The experiments described in this paper support this idea: we found that learners who used our conceptual models were able to analyze and solve problems conceptually, while learners who used task-oriented learning materials of equivalent scope employed aimless trial and error.     

Assessing traceability of software engineering artifacts

The generation of traceability links or traceability matrices is vital to many software engineering activities. It is also person-power intensive, time-consuming, error-prone, and lacks tool support. The activities that require traceability information include, but are not limited to, risk analysis, impact analysis, criticality assessment, test coverage analysis, and verification and validation of software systems. Information Retrieval (IR) techniques have been shown to assist with the automated generation of traceability links by reducing the time it takes to generate the traceability mapping. Researchers have applied techniques such as Latent Semantic Indexing (LSI), vector space retrieval, and probabilistic IR and have enjoyed some success. This paper concentrates on examining issues not previously widely studied in the context of traceability: the importance of the vocabulary base used for tracing and the evaluation and assessment of traceability mappings and methods using secondary measures. We examine these areas and perform empirical studies to understand the importance of each to the traceability of software engineering artifacts.     

Protocols in the use of empirical software engineering artifacts

If empirical software engineering is to grow as a valid scientific endeavor, the ability to acquire, use, share, and compare data collected from a variety of sources must be encouraged. This is necessary to validate the formal models being developed within computer science. However, within the empirical software engineering community this has not been easily accomplished. This paper analyses experiences from a number of projects, and defines the issues, which include the following: (1) How should data, testbeds, and artifacts be shared? (2) What limits should be placed on who can use them and how? How does one limit potential misuse? (3) What is the appropriate way to credit the organization and individual that spent the effort collecting the data, developing the testbed, and building the artifact? (4) Once shared, who owns the evolved asset? As a solution to these issues, the paper proposes a framework for an empirical software engineering artifact agreement. Such an agreement is intended to address the needs for both creator and user of such artifacts and should foster a market in making available and using such artifacts. If this framework for sharing software engineering artifacts is commonly accepted, it should encourage artifact owners to make the artifacts accessible to others (gaining credit is more likely and misuse is less likely). It may be easier for other researchers to request artifacts since there will be a well-defined protocol for how to deal with relevant matters.     

Commonality and variability in software engineering

The article describes how to perform domain engineering by identifying the commonalities and variabilities within a family of products. Through interesting examples dealing with reuse libraries, design patterns, and programming language design, the authors suggest a systematic scope, commonalities, and variabilities approach to formal analysis. Their SCV analysis has been an integral part of the FAST (Family-oriented Abstraction, Specification, and Translation) technology applied to over 25 domains at Lucent Technologies     

Challenges of working with artifacts in requirements engineering and software engineering

When developing or evolving software systems of non-trivial size, having the requirements properly documented is a crucial success factor. The time and effort required for creating and maintaining non-code artifacts are significantly influenced by the tools with which practitioners view, navigate and edit these artifacts. This is not only true for requirements, but for any artifacts used when developing or evolving systems. However, there is not much evidence about how practitioners actually work with artifacts and how well software tools support them. Therefore, we conducted an exploratory study based on 29 interviews with software practitioners to understand the current practice of presenting and manipulating artifacts in tools, how practitioners deal with the challenges encountered, and how these challenges affect the usability of the tools used. We found that practitioners typically work with several interrelated artifacts concurrently, less than half of these artifacts can be displayed entirely on a large screen, the artifact interrelationship information is often missing, and practitioners work collaboratively on artifacts without sufficient support. We identify the existing challenges of working with artifacts and discuss existing solutions proposed addressing them. Our results contribute to the body of knowledge about how practitioners work with artifacts when developing or evolving software, the challenges they are faced with, and the attempts to address these challenges.     

LCD models to analyze and simulate motion artifacts

Abstract— In this paper, two models to evaluate the temporal behavior of liquid‐crystal displays are described: a model assuming a linear display behavior and a model that incorporates non‐linear effects. For the linear temporal model, it can be predicted that the response time starts to contribute to motion blur when it is longer than one‐sixth of the hold time and becomes dominant when it is longer than eight times the hold time. The non‐linear model can be used to visualize the appearance of effects that cannot be determined via linear system theory. Also, some means to reduce display artifacts are described and its impact is illustrated. Although the main focus in this article is on the temporal behavior of liquid‐crystal displays, the spatial properties defined by the pixel structure can be simulated as well. A formula for the spatio‐temporal display behavior is given, which can be evaluated numerically to simulate the perceived image for arbitrary image‐sequence input material.     

Mental models and software maintenance

Understanding how a program is constructed and how it functions are significant components of the task of maintaining or enhancing a computer program. We have analyzed vidoetaped protocols of experienced programmers as they enhanced a personnel data base program. Our analysis suggests that there are two strategies for program understanding, the systematic strategy and the as-needed strategy. The programmer using the systematic strategy traces data flow through the program in order to understand global program behavior. The programmer using the as-needed strategy focuses on local program behavior in order to localize study of the program. Our empirical data show that there is a strong relationship between using a systematic approach to acquire knowledge about the program and modifying the program successfully. Programmers who used the systematic approach to study the program constructed successful modifications; programmers who used the as-needed approach failed to construct successful modifications. Programmers who used the systematic strategy gathered knowledge about the causal interactions of the program's functional components. Programmers who used the as-needed strategy did not gather such causal knowledge and therefore failed to detect interactions among components of the program.     

Recalibrating software reliability models

There is no universally applicable software reliability growth model which can be trusted to give accurate predictions of reliability in all circumstances. A technique of analyzing predictive accuracy called the u-plot allows a user to estimate the relationship between the predicted reliability and the true reliability. It is shown how this can be used to improve reliability predictions in a very general way by a process of recalibration. Simulation results show that the technique gives improved reliability predictions in a large proportion of cases. However, a user does not need to trust the efficacy of recalibration, since the new reliability estimates produced by the technique are truly predictive and their accuracy in a particular application can be judged using the earlier methods. The generality of this approach suggests its use whenever a software reliability model is used. Indeed, although this work arose from the need to address the poor performance of software reliability models, it is likely to have applicability in other areas such as reliability growth modeling for hardware     

软件Agent的通信模型

在分布式多Agent系统中,Agent之间的通信是合作的基础,但Agent技术综合了人工智能、分布式计算、软件工程等多种领域的成就,应用面广,所以通信机制多种多样,非常灵活,分析了Agent系统中最常用的3种通信模型及其优缺点,适用领域,介绍了几种综合运用多种通信方式的实例,讨论了软件Agent通信中的安全问题并对未来的发展趋势进行了展望。     

Integrating business and software development models

Developing the right products the right way is challenging, not least in software product development. It requires sound business decisions as well as good engineering practices. Various software development life-cycle models can be mapped to business decision models by mapping business decision gates and major development milestones. Two well-known life-cycle models have been mapped to the ABB Gate Model, a business decision model for product development projects that was developed to ensure that released products could be successfully deployed into the marketplace.     

Mining software repositories for comprehensible software fault prediction models

Software managers are routinely confronted with software projects that contain errors or inconsistencies and exceed budget and time limits. By mining software repositories with comprehensible data mining techniques, predictive models can be induced that offer software managers the insights they need to tackle these quality and budgeting problems in an efficient way. This paper deals with the role that the Ant Colony Optimization (ACO)-based classification technique AntMiner+ can play as a comprehensible data mining technique to predict erroneous software modules. In an empirical comparison on three real-world public datasets, the rule-based models produced by AntMiner+ are shown to achieve a predictive accuracy that is competitive to that of the models induced by several other included classification techniques, such as C4.5, logistic regression and support vector machines. In addition, we will argue that the intuitiveness and comprehensibility of the AntMiner+ models can be considered superior to the latter models.     

Dealing with variability in context-aware mobile software

Mobile context-aware software pose a set of challenging requirements to developers as these applications exhibit novel features, such as handling varied sensing devices and dynamically adapting to the user’s context (e.g. his or her location), and evolve quickly according to technological advances.In this paper, we discuss how to handle variability both across different domains and during the evolution of a single application. We present a set of design structures for solving different problems related with mobility (such as location sensing, behaviour adaptation, etc.), together with the design rationale underlying them, and show how these sound micro-architectural constructs impact on variability. Our presentation is illustrated with case studies in different domains.     

Managing infinite variability in mobile terminal software

Mobile terminals have evolved from basic portable telephones to complex and diverse devices that encompass dozens of other features, ranging from tri‐dimensional games to office suites with data transmission capabilities. Variability is value: mobile terminal manufacturers must succeed in fulfilling the requirements of hundreds of mobile telecom operators worldwide, and at the same time increase the value of their brand by adopting a common user interface style while offering the features that the target end‐user category desires. This makes for practically infinite variability and creates a business problem. The complexity of the variability problem increases due to issues such as the ability to ‘plug and play’ and ‘feature descension’ (the down‐scaling of high‐end features and their introduction into lower‐end models). The main lesson we have learned from our experience in this field is that the application of relatively simple architectural patterns usually eases up management of the complexity at the architectural level. However, tackling the variability problem at the technical level is ineffective unless the organization is able to ensure the application of the solutions. We analyze the main challenges that lie behind the variability problem in mobile terminals, at both technical and organizational level, and illustrate some of the solutions we have implemented together with our product developers and system architects. Our experience calls for more applied research in the area of variability management, as well as for a number of enhancements to academic curricula. Copyright © 2005 John Wiley & Sons, Ltd.     

构件行为模型的构造研究

提出了基于 UML构件规格说明自动构造构件行为模型的方法 ,并用一个实例对该方法进行了说明。该方法构造的构件行为模型包含状态与状态之间的转换 ,接口操作作为状态转换弧上的输入 ,能够很好地体现接口的操作调用序列 ,因而可以作为构件测试的测试模型 ,对于构件的开发者和使用者进行构件的黑盒测试以及第三方构件的评估很有价值。     

Planning models for software reliability and cost

This paper presents modeling frameworks for distributing development effort among software components to facilitate cost-effective progress toward a system reliability goal. Emphasis on components means that the frameworks can be used, for example, in cleanroom processes and to set certification criteria. The approach, based on reliability allocation, uses the operational profile to quantify the usage environment and a utilization matrix to link usage with system structure. Two approaches for reliability and cost planning are introduced: Reliability-Constrained Cost-Minimization (RCCM) and Budget-Constrained Reliability-Maximization (BCRM). Efficient solutions are presented corresponding to three general functions for measuring cost-to-attain failure intensity. One of the functions is shown to be a generalization of the basic COCOMO form. Planning within budget, adaptation for other cost functions and validation issues are also discussed. Analysis capabilities are illustrated using a software system consisting of 26 developed modules and one procured module. The example also illustrates how to specify a reliability certification level, and minimum purchase price, for the procured module     

产品线可变性的需求方法研究

软件产品线领域需求记录了不同软件产品的共性和可变性。在现有需求过程框架下,对产品线需求获取方法与需求分析方法进行了研究,完善了产品线需求可变性的管控机制。以原子需求为视点,提出了利用需求场景获取产品线领域需求的方法;通过原子需求构建的产品需求矩阵与用例需求矩阵,分析得出需求资源的可变性关系;通过可变性关系的形式化描述,建立产品线可变性用例模型。     

Inference from models of software systems

The inferences which can validly be drawn about a software system based on reasoning about a model of the system depend on the precise relationship between the system and the model. Formal properties of a variety of such modeling relationships are examined, particularly relationships in which, if a given computation is possible in the system, the corresponding computations (if any) are also possible in the model. Therefore, if a particular (perhaps undesirable) computation is not possible in the model, no corresponding computation is possible in the original system. Inferences like these can be used to show, for example, that a particular error is absent from the original system if it is not manifested in the model. It is shown that many modeling techniques that are intuitively rather natural and easy to describe are of this kind.