Code quality analysis in open source software development

Abstract Proponents of open source style software development claim that better software is produced using this model compared with the traditional closed model. However, there is little empirical evidence in support of these claims. In this paper, we present the results of a pilot case study aiming: (a) to understand the implications of structural quality; and (b) to figure out the benefits of structural quality analysis of the code delivered by open source style development. To this end, we have measured quality characteristics of 100 applications written for Linux, using a software measurement tool, and compared the results with the industrial standard that is proposed by the tool. Another target of this case study was to investigate the issue of modularity in open source as this characteristic is being considered crucial by the proponents of open source for this type of software development. We have empirically assessed the relationship between the size of the application components and the delivered quality measured through user satisfaction. We have determined that, up to a certain extent, the average component size of an application is negatively related to the user satisfaction for this application.     

藏文Web应用的质量模糊综合评判

为给藏文Web应用提供一种定量的质量评判方法,将模糊数学中的模糊综合评判方法应用于对Web中藏文文字的规范呈现、藏文Web中的功能特性、效率和易用性等因素进行综合评价,提出了数学模型和评判方法,同时说明在模糊综合评判中权重至关重要,并且给出了权重的确定方法.最后通过实例说明这种方法在藏文Web评判中的应用中是有效和可行的.     

Formalizing and validating the web quality model for web source quality evaluation

The proposed web quality model (WebQM) is formalized with ISO/IEC Z language and empirically studied based on the Structural Equation Modeling (SEM) approach. By building the sample data set and constructing the structure equation model, the goodness-of-fit of WebQM is analyzed based on generalized least square method. A web source quality evaluation process based on validated WebQM is implemented and verified as more objective and credible, because the weights of quality criteria are automatically produced in the validation procedure, which avoids the subjective weight assignment in some classic assessment approaches. The model validation and implemented evaluation show that WebQM fits the real web source quality data and is feasible, reliable, and effective for web source quality evaluation.     

A dynamic software release model

The determination of optimal software release times constitutes an interesting decision making problem which involves the stochastic structure of the underlying software reliability model, as well as various cost parameters. There is an apparent tradeoff between testing the software further to improve its reliability, and releasing it for operational use to decrease the costs. We propose and analyze in depth a new dynamic model with sufficient generality. After each failure, a debugging activity, possibly imperfect, is undertaken and a decision is made regarding the duration of additional testing. If no failure is observed during this time, then the software is released. Otherwise, the failure is debugged and the decision process is repeated in a dynamic fashion. The problem is formulated using dynamic programming and interesting characterizations of the optimal release policy are presented. The dynamic solution procedure is demonstrated by some numerical illustrations.     

The impact of software evolution and reuse on software quality

This paper presents a case study of a software project in the maintenance phase. The case study was based on a sample of modules, representing about 1.3 million lines of code, from a very large telecommunications system. Software quality models were developed to predict the number of faults expected from the coding through operations phases. Since modules from the prior release were often reused to develop a new release, one model incorporated reuse data as additional independent variables. We compare this model's performance to a similar model without reuse data.Software quality models often have product metrics as the only input data for predicting quality. There is an implicit assumption that all the modules have had a similar development history, so that product attributes are the primary drivers of different quality levels. Reuse of software as components and software evolution do not fit this assumption very well, and consequently, traditional models for such environments may not have adequate accuracy. Focusing on the software maintenance phase, this study demonstrated that reuse data can significantly improve the predictive accuracy of software quality models.     

Definition and collection of metrics for comprehensive software measurement

The approach to defining software metrics in terms of software models such as control graphs or call graphs has two limitations. First, since a model of the software will not, by its very nature, have all the properties of the software itself, the model-based approach is not well suited as a basis for comprehensive programmes of software measurement. Secondly, although software metrics are usually well defined in terms of the software models to which they relate, the models themselves are often not well defined in terms of the source code, or other software artefact, which they purport to measure. The paper describes approaches to metric definition designed to overcome these limitations.     

A formal approach for run-time verification of web applications using scope-extended LTL

ContextIn the past decade, the World Wide Web has been subject to rapid changes. Web sites have evolved from static information pages to dynamic and service-oriented applications that are used for a broad range of activities on a daily basis. For this reason, thorough analysis and verification of Web Applications help assure the deployment of high quality applications.ObjectivesIn this paper, an approach is presented to the formal verification and validation of existing web applications. The approach consists of using execution traces of a web application to automatically generate a communicating automata model. The obtained model is used to model checking the application against predefined properties, to perform regression testing, and for documentation.MethodsTraces used in the proposed approach are collected by monitoring a web application while it is explored by a user or a program. An automata-based model is derived from the collected traces by mapping the pages of the application under test into states and the links and forms used to browse the application into transitions between the states. Properties, meanwhile, express correctness and quality requirements on web applications and might concern all states of the model; in many cases, these properties concern only a proper subset of the states, in which case the model is refined to designate the subset of the global states of interest. A related problem of property specification in Linear Temporal Logic (LTL) over only a subset of states of a system is solved by means of specialized operators that facilitate specifying properties over propositional scopes in a concise and intuitive way. Each scope constitutes a subset of states that satisfy a propositional logic formula.ResultsAn implementation of the verification approach that uses the model checker Spin is presented where an integrated toolset is developed and empirical results are shown. Also, Linear Temporal Logic is extended with propositional scopes.Conclusiona formal approach is developed to build a finite automata model tuned to features of web applications that have to be validated, while delegating the task of property verification to an existing model checker. Also, the problem of property specification in LTL over a subset of the states of a given system is addressed, and a generic and practical solution is proposed which does not require any changes in the system model by defining specialized operators in LTL using scopes.     

Modelling methods for web application verification and testing: state of the art

Models are considered an essential step in capturing different system behaviours and simplifying the analysis required to check or improve the quality of software. Verification and testing of web software requires effective modelling techniques that address the specific challenges of web applications. In this study we survey 24 different modelling methods used in web site verification and testing. Based on a short catalogue of desirable properties of web applications that require analysis, two different views of the methods are presented: a general categorization by modelling level, and a detailed comparison based on property coverage. Copyright © 2008 John Wiley & Sons, Ltd.     

Empirical study of open source software selection for adoption,based on software quality characteristics

Currently, open source software (OSS) products have started to become popular in the market as an alternative to traditional proprietary or closed source software. Governments and organizations are beginning to adopt OSS on a large scale and several governmental initiatives have encouraged the use of OSS in the private sector. One major issue for the government and private sector is the selection of appropriate OSS. This paper uses new internal quality characteristics for selecting OSS that can be added to the dimensions of DeLone and McLean information systems’ model. Through this study, the quality characteristics are organized in a two level hierarchy, which list characteristics and sub-characteristics that are interconnected with three main dimensions: system quality, information quality and service quality. These characteristic dimensions are tailored to the criteria having been built from literature study and standard for software quality and guidelines. This paper presents case study results of applying the proposed quality characteristic on eight different open source software that are divided between open source network tools and learning management systems.     

基于正交设计的软件过程度量分析方法

软件过程度量的一项工作是分析、确定影响过程能力的显著因素,并将其结果作为建立过程改进决策的基础,即在软件过程度量中找出影响某一指标的主要因素,针对这些因素对软件过程加以控制和改进.这一过程对建立过程改进的有效决策是至关重要的.将数理统计学中的正交设计方法引入到软件过程度量中,提出了一种基于正交设计的软件过程度量分析方法,量化标识软件过程的主要因素,协助决策者找出需要进行重点监控的关键因素,为过程改进提供了基础.     

Reliability analysis and optimal version-updating for open source software

Context

Although reliability is a major concern of most open source projects, research on this problem has attracted attention only recently. In addition, the optimal version-dating for open source software considering its special properties is not yet discussed.

Objective

In this paper, the reliability analysis and optimal version-updating for open source software are studied.

Method

A modified non-homogeneous Poisson process model is developed for open source software reliability modeling and analysis. Based on this model, optimal version-updating for open source software is investigated as well. In the decision process, the rapid release strategy and the level of reliability are the two most important factors. However, they are essentially contradicting with each other. In order to consider these two conflicting factors simultaneously, a new decision model based on multi-attribute utility theory is proposed.

Results

Our models are tested on the real world data sets from two famous open source projects: Apache and GNOME. It is found that traditional software reliability models provide overestimations of the reliability of open source software. In addition, the proposed decision model can help management to make a rational decision on the optimal version-updating for open source software.

Conclusion

Empirical results reveal that the proposed model for open source software reliability can describe the failure process more accurately. Furthermore, it can be seen that the proposed decision model can assist management to appropriately determine the optimal version-update time for open source software.     

软件研发中的项目质量管理工具与技术

重点介绍了软件研发中的项目质量管理常用的工具与技术,涉及配置管理、软件测试技术、帕累托分析、质量功能分布图等质量管理工具。     

面向CMMI的软件度量分析过程研究与应用

为了辅助软件组织有效实施符合CMMI模型的软件度量过程,提出了一种GREDR过程框架模型,以指导软件度量的目标策划与过程实施。在实际软件项目过程中的应用结果表明：GREDR模型能够提高软件度量过程的系统性与效用。     

Comparing practices for reuse in integration‐oriented software product lines and large open source software projects

This article compares the organization and practices for software reuse in integration‐oriented software product lines (SPLs) and open source software projects. The main observation is that both approaches are successful regarding large variability and reuse, but differ widely in their practices and organization. To capture practices in large open source projects, we describe an open compositional model, which reflects their more decentralized organization of software development. We capture key practices and organizational forms for this and validate these by comparing four case studies of this model. Two of these studies are based on published SPL case studies, for the other two we analyze the practices in two large and successful open source projects based on their published developer documentation. Our analysis highlights key differences between the practices in the two open source organizations and the more integrational practices used in the other two cases. Finally, we discuss which practices are successful in which environment and how the current practices can move towards more open, widely scoped and distributed software development. Copyright © 2010 John Wiley & Sons, Ltd.     

Managing Problems for Global Software Production – Experience and Lessons

With the increase in size and complexity of current software projects, many large companies have established global software production lines over the world to develop and deliver software products with collaborative software development processes involving multiple teams located at different sites. Supporting global software production needs an effective software-engineering environment to meet the special requirements of the collaborative software development process, diverse management methods and engineering practice. WWW technology provides powerful means to set up an enterprise-oriented software engineering environment for global software production due to its advantages in networking, global access, internationalization, and communication. Although there are many articles addressing the methods and experience in building web-based applications systems and tools, very few papers discuss the real-world problems and solutions in the development and deployment of web-based software tools to support a collaborative software development process for global software production. This paper discusses the real world issues, and reports our experience and lessons in building and deploying a web-based problem information management system (PIMS) to support global software development processes at Fujitsu. It focuses on the real issues and needs of current collaborative development process involving multiple teams, and highlights the benefits and impact of the PIMS on global software production. Moreover, it discusses our technical solutions and trade-offs in the development of PIMS, and shares our experience and lessons. Furthermore, it introduces a new data-centered conceptual process model to support diverse collaborative processes for project and problem management in global software production. Finally, the paper shares our key successes and weaknesses, and reports our experience and lessons in the deployment of the system.     

A framework for QoS-aware binding and re-binding of composite web services

QoS-aware dynamic binding of composite services provides the capability of binding each service invocation in a composition to a service chosen among a set of functionally equivalent ones to achieve a QoS goal, for example minimizing the response time while limiting the price under a maximum value.This paper proposes a QoS-aware binding approach based on Genetic Algorithms. The approach includes a feature for early run-time re-binding whenever the actual QoS deviates from initial estimates, or when a service is not available. The approach has been implemented in a framework and empirically assessed through two different service compositions.     

Defect proneness estimation and feedback approach for software design quality improvement

Context

Modern software engineering demands professionals and researchers to proactively and collectively work towards exploring and experimenting viable and valuable mechanisms in order to extract all kinds of degenerative bugs, security holes, and possible deviations at the initial stage. Having understood the real need here, we have introduced a novel methodology for the estimation of defect proneness of class structures in object oriented (OO) software systems at design stage.

Objective

The objective of this work is to develop an estimation model that provides significant assessment of defect proneness of object oriented software packages at design phase of SDLC. This frame work enhances the efficiency of SDLC through design quality improvement.

Method

This involves a data driven methodology which is based on the empirical study of the relationship existing between design parameters and defect proneness. In the first phase, a mapping of the relationship between the design metrics and normal occurrence pattern of defects are carried out. This is represented as a set of non linear multifunctional regression equations which reflects the influence of individual design metrics on defect proneness. The defect proneness estimation model is then generated by weighted linear combination of these multifunctional regression equations. The weighted coefficients are evaluated through GQM (Goal Question Metric) paradigm.

Results

The model evaluation and validation is carried out with a selected set of cases which is found to be promising. The current study is successfully dealt with three projects and it opens up the opportunity to extend this to a wide range of projects across industries.

Conclusion

The defect proneness estimation at design stage facilitates an effective feedback to the design architect and enabling him to identify and reduce the number of defects in the modules appropriately. This results in a considerable improvement in software design leading to cost effective products.     

软件研发中的项目质量管理过程研究

重点介绍了软件研发中的项目质量管理知识体系,涉及软件质量计划编制、软件质量保证、软件质量控制等过程。