Model-based early and rapid estimation of COSMIC functional size – An experimental evaluation

ContextFunctional size measurement methods are widely used but have two major shortcomings: they require a complete and detailed knowledge of user requirements, and they involve relatively expensive and lengthy processes.ObjectiveUML is routinely used in the software industry to effectively describe software requirements in an incremental way, so UML models grow in detail and completeness through the requirements analysis phase. Here, we aim at defining the characteristics of increasingly more refined UML requirements models that support increasingly more sophisticated – hence presumably more accurate – size estimation processes.MethodWe consider the COSMIC method and three alternative processes (two of which are proposed in this paper) to estimate COSMIC size measures that can be applied to UML diagrams at progressive stages of the requirements definition phase. Then, we check the accuracy of the estimates by comparing the results obtained on a set of projects to the functional size values obtained with the standard COSMIC method.ResultsOur analysis shows that it is possible to write increasingly more detailed and complete UML models of user requirements that provide the data required by COSMIC size estimation methods, which in turn yield increasingly more accurate size measure estimates of the modeled software. Initial estimates are based on simple models and are obtained quickly and with little effort. The estimates increase their accuracy as models grow in completeness and detail, i.e., as the requirements definition phase progresses.ConclusionDevelopers that use UML for requirements modeling can obtain an early estimation of the application size at the beginning of the development process, when only a very simple UML model has been built for the application, and can obtain increasingly more accurate size estimates while the knowledge of the product increases and UML models are refined accordingly.     

On evaluating the layout of UML diagrams for program comprehension

UML class and sequence diagrams are helpful for understanding the static structure and dynamic behavior of a software system. Algorithms and tools have been developed to generate these UML diagrams automatically for program understanding purposes. Many tools, however, often ignore perceptual factors in the layout of these diagrams. Therefore, users still have to spend much time and effort rearranging boxes and lines to make the diagram understandable. This article presents key criteria and guidelines for the effective layout of UML class and sequence diagrams from the perspective of perceptual theories. Two UML tools are evaluated to illustrate how the criteria can be applied to assess the readability of their generated diagrams. Kenny Wong is an Associate Professor in the Department of Computing Science at the University of Alberta. His main areas of research include software comprehension, evolution, and visualization. This research includes building, using, and evaluating integrated environments for reverse engineering, and devising strategies to understand and evolve diverse software systems. He is General Chair of the 2007 International Conference on Program Comprehension in Banff, and Program Chair of the 2008 International Conference on Software Maintenance in Beijing. Dabo Sun is an M.Sc. student in the Department of Computing Science at the University of Alberta. His research interests include program comprehension, software visualization, and end-user software engineering. He has assisted the teaching of courses in software engineering and web information systems. He also has been working as a software engineer on developing and maintaining industrial software systems.     

Automated COSMIC Function Point measurement using a requirements engineering ontology

ContextThere are two interrelated difficulties in requirements engineering processes. First, free-format modelling practices in requirements engineering activities may lead to low quality artefacts and productivity problems. Second, the COSMIC Function Point Method is not yet widespread in the software industry because applying measurement rules to imprecise and ambiguous textual requirements is difficult and requires additional human measurement effort. This challenge is common to all functional size measurement methods.ObjectiveIn this study, alternative solutions have been investigated to address these two difficulties. Information created during the requirements engineering process is formalized as an ontology that also becomes a convenient model for transforming requirements into COSMIC Function Point Method concepts.MethodA method is proposed to automatically measure the functional size of software by using the designed ontology. The proposed method has been implemented as a software application and verified with real projects conducted within the ICT department of a leading telecommunications provider in Turkey.ResultsWe demonstrated a novel method to measure the functional size of software in COSMIC FP automatically. It is based on a newly developed requirements engineering ontology. Our proposed method has several advantages over other methods explored in previous research.ConclusionManual and automated measurement results are in agreement, and the tool is promising for the company under study and for the industry at large.     

Towards a simplified definition of Function Points

BackgroundThe measurement of Function Points is based on Base Functional Components. The process of identifying and weighting Base Functional Components is hardly automatable, due to the informality of both the Function Point method and the requirements documents being measured. So, Function Point measurement generally requires a lengthy and costly process.ObjectivesWe investigate whether it is possible to take into account only subsets of Base Functional Components so as to obtain functional size measures that simplify Function Points with the same effort estimation accuracy as the original Function Points measure. Simplifying the definition of Function Points would imply a reduction of measurement costs and may help spread the adoption of this type of measurement practices. Specifically, we empirically investigate the following issues: whether available data provide evidence that simplified software functionality measures can be defined in a way that is consistent with Function Point Analysis; whether simplified functional size measures by themselves can be used without any appreciable loss in software development effort prediction accuracy; whether simplified functional size measures can be used as software development effort predictors in models that also use other software requirements measures.MethodWe analyze the relationships between Function Points and their Base Functional Components. We also analyze the relationships between Base Functional Components and development effort. Finally, we built effort prediction models that contain both the simplified functional measures and additional requirements measures.ResultsSignificant statistical models correlate Function Points with Base Functional Components. Basic Functional Components can be used to build models of effort that are equivalent, in terms of accuracy, to those based on Function Points. Finally, simplified Function Points measures can be used as software development effort predictors in models that also use other requirements measures.ConclusionThe definition and measurement processes of Function Points can be dramatically simplified by taking into account a subset of the Base Functional Components used in the original definition of the measure, thus allowing for substantial savings in measurement effort, without sacrificing the accuracy of software development effort estimates.     

On the conversion between IFPUG and COSMIC software functional size units: A theoretical and empirical study

Since 1984 the International Function Point Users Group (IFPUG) has produced and maintained a set of standards and technical documents about a functional size measurement methods, known as IFPUG, based on Albrecht function points. On the other hand, in 1998, the Common Software Measurement International Consortium (COSMIC) proposed an improved measurement method known as full function points (FFP). Both the IFPUG and the COSMIC methods both measure functional size of software, but produce different results. In this paper, we propose a model to convert functional size measures obtained with the IFPUG method to the corresponding COSMIC measures. We also present the validation of the model using 33 software projects measured with both methods. This approach may be beneficial to companies using both methods or migrating to COSMIC such that past data in IFPUG can be considered for future estimates using COSMIC and as a validation procedure.     

Source-code comprehension tasks supported by UML design models: Results from a controlled experiment and a differentiated replication

Objective: The main objective is to investigate whether the comprehension of object-oriented source-code increases when it is added with UML class and sequence diagrams produced in the software design phase.Methods: We conducted a controlled experiment and a differentiated replication with young software maintainers. In particular, groups of Bachelor and Master students were involved.Results: The results show that more experienced participants better comprehend source-code when added with UML design models. An average improvement (or benefit) of circa 12% was achieved when the participants accomplished the comprehension task with UML class and sequence diagrams. The results of an analysis on the time to accomplish comprehension tasks showed that less experienced participants significantly spent more time when comprehending source-code with UML design models. This kind of participants spent on average 44.8% of the time to accomplish the same task with source-code alone.Implications: It is useless to give UML design models to comprehend source-code in case maintainers are not adequately experienced with the UML. Furthermore, the less the experience of participants, the more the time to accomplish a comprehension task with UML diagram is.     

基于UML的COSMIC-FFP度量方法

针对目前的软件规模度量方法中存在的主观性强、可重复性差的问题,通过将UML引入到度量过程中来改善当前的软件度量方法。分析UML主要部件(用例图、类图和时序图)的语义和COSMIC-FFP的主要元素(功能用户、层、边界、数据组和功能过程),建立其间的对应关系,给出15条映射规则,同时还提出基于UML的COSMIC-FFP度量步骤。实例结果证明,该方法能客观有效地度量软件功能规模。     

Source code size estimation approaches for object-oriented systems from UML class diagrams: A comparative study

BackgroundSource code size in terms of SLOC (source lines of code) is the input of many parametric software effort estimation models. However, it is unavailable at the early phase of software development.ObjectiveWe investigate the accuracy of early SLOC estimation approaches for an object-oriented system using the information collected from its UML class diagram available at the early software development phase.MethodWe use different modeling techniques to build the prediction models for investigating the accuracy of six types of metrics to estimate SLOC. The used techniques include linear models, non-linear models, rule/tree-based models, and instance-based models. The investigated metrics are class diagram metrics, predictive object points, object-oriented project size metric, fast&&serious class points, objective class points, and object-oriented function points.ResultsBased on 100 open-source Java systems, we find that the prediction model built using object-oriented project size metric and ordinary least square regression with a logarithmic transformation achieves the highest accuracy (mean MMRE = 0.19 and mean Pred(25) = 0.74).ConclusionWe should use object-oriented project size metric and ordinary least square regression with a logarithmic transformation to build a simple, accurate, and comprehensible SLOC estimation model.     

基于UML模型的全功能点自动化度量

软件规模在项目估算和决策中起着举足轻重的作用。基于软件需求从用户角度和功能角度度量规模的全功能点(FFP)广受欢迎，但为手工操作，弊端显而易见，所以亟需自动化度量。本文提出并实现了基于UML模型全功能点自动化度量系统，不但能得到精确的量化结果，而且能减轻工作量、降低花费，以及很大程度上避免抽取数据及度量过程中差错所造成的风险，更重要的是具有可重复性，从而易于功能规模度量方法的推广。     

由序列图合成状态图

序列图和状态图对于描述和理解面向对象软件系统有着极其重要的作用。符合UML标准的序列图和状态图存在信息重叠，根据序列图提供的信息可以合成状态图。给出了在Rational Rose中由序列图合成状态图工具的实现。     

An exploratory study on the accuracy of FPA to COSMIC measurement method conversion types

BackgroundFunctional size measurement methods are increasingly being adopted by software organizations due to the benefits they provide to software project managers. The Function Point Analysis (FPA) measurement method has been used extensively and globally in software organizations. The COSMIC measurement method is considered a second generation FSM method, because of the novel aspects it brings to the FSM field. After the COSMIC method was proposed, the issue of convertibility from FPA to COSMIC method arose, the main problem being the ability to convert FPA historical data to the corresponding COSMIC Function Point (CFP) data with a high level of accuracy, which would give organizations the ability to use the data in their future planning. Almost all the convertibility studies found in the literature involve converting FPA measures to COSMIC measures statistically, based on the final size generated by both methods.ObjectivesThis paper has three main objectives. The first is to explore the accuracy of the conversion type that converts FPA measures to COSMIC measures statistically, and that of the type that converts FPA transaction function measures to COSMIC measures. The second is to propose a new conversion type that predicts the number of COSMIC data movements based on the number of file type references referenced by all the elementary processes in a single application. The third is to compare the accuracy of our proposed conversion type with the other two conversion types found in the literature.MethodOne dataset from the management information systems domain was used to compare the accuracy of all three conversion types using a systematic conversion approach that applies three regression models: Ordinary Least Squares, Robust Least Trimmed Squares, and logarithmic transformation were used. Four datasets from previous studies were used to evaluate the accuracy of the three conversion types, to which the Leave One Out Cross Validation technique was applied to obtain the measures of fitting accuracy.ResultsThe conversion type most often used as well as the conversion type based on transaction function size were found to generate nonlinear, inaccurate and invalid results according to measurement theory. In addition, they produce a loss of measurement information in the conversion process, because of the FPA weighting system and FPA structural problems, such as illegal scale transformation. Our proposed conversion type avoids the problems inherent in the other two types but not the nonlinearity problem. Furthermore, the proposed conversion type has been found to be more accurate than the other types when the COSMIC functional processes comprise dataset applications that are systematically larger than their corresponding FPA elementary processes, or when the processes vary from small to large. Finally, our proposed conversion type delivered better results over the tested datasets, whereas, in general, there is no statistical significant difference between the accuracy of the conversion types examined for every dataset, particularly the conversion type most often used is not the most accurate.ConclusionsOur proposed conversion type achieves accurate results over the tested datasets. However, the lack of knowledge needed to use it over all the datasets in the literature limits the value of this conclusion. Consequently, practitioners converting from FPA to COSMIC should not stay with only one conversion type, assuming that it is the best. In order to achieve a high level of accuracy in the conversion process, all three conversion types must be tested via a systematic conversion approach.     

简化数据流图的功能点分析方法研究

随着软件工程在各个行业的日益深入以及软件规模的日益庞大,在软件生命周期的早期阶段对软件系统进行规模度量显得尤为重要。在需求分析阶段所建立的逻辑模型的基础上,使用E-R图来简化数据流图,并结合功能点分析的度量原理,以简化的数据流图作为度量要素,详细给出了度量简化数据流图的映射规则和度量规则,以实例验证了这些规则的使用方法,简单实用。     

基于UML的软件使用模型生成技术研究

软件可靠性测试是高可靠软件质量保证的重要过程，而软件使用模型则是进行软件可靠性测试的基础。UML(Unified Modeling Language)作为事实上的工业标准，在软件开发中得到了日益广泛的应用。研究基于UML的软件可靠性测试具有很强的现实意义。利用在软件开发早期阶段生成的UML模型，如用例图、顺序图、活动图，可以生成软件使用模型，进而可据此产生测试用例。     

UML2．0顺序图的XYZ／E时序逻辑语义研究

UML2．0顺序图适合于描述软件体系结构的各个组件之间和复合组件内部各个子组件之间的动态交互行为，但由于UML2．0顺序图的语义不够精确，使得它的描述结果不利于进一步的分析和验证。基于此，本文在定义UML2．0顺序图的语法和语法约束的基础上，给出了UML2．0顺序图的XYZ／E时序逻辑语义，为使用UML2．0顺序图与XYZ／E相结合的方式来描述软件体系结构的动态交互行为奠定了基础。     

Static generation of UML sequence diagrams

UML sequence diagrams are visual representations of object interactions in a system and can provide valuable information for program comprehension, debugging, maintenance, and software archeology. Sequence diagrams generated from legacy code are independent of existing documentation that may have eroded. We present a framework for static generation of UML sequence diagrams from object-oriented source code. The framework provides a query refinement system to guide the user to interesting interactions in the source code. Our technique involves constructing a hypergraph representation of the source code, traversing the hypergraph with respect to a user-defined query, and generating the corresponding set of sequence diagrams. We implemented our framework as a tool, StaticGen (supporting software: StaticGen), analyzing a corpus of 30 Android applications. We provide experimental results demonstrating the efficacy of our technique (originally appeared in the Proceedings of Fundamental Approaches to Software Engineering—20th International Conference, FASE 2017, Held as Part of the European Joint Conferences on Theory and Practice of Software, ETAPS 2017, Uppsala, Sweden, April 22–29, 2017).

     

基于UML图和不同粒度切片的回归测试研究

针对面向对象软件回归测试的新特点,本文引入了基于UML图的不同粒度切片。首先,对描述类间关系的UML类图和描述状态变迁关系的UML状态图形式化定义。接着,对定义的图进行切片分析,其中类间测试提出一种基于UML类图的粗粒度切片工具;类内测试提出一种基于UML状态图细粒度切片的方法。最后,将其应用于销售订单系统,结果表明以上两种分析方法可以有效地提高回归测试效率。     

The impact of UML modeling on defect density and defect resolution time in a proprietary system

Background: The contribution of modeling in software development has been a subject of debates. The proponents of model-driven development argue that a big upfront modeling requires substantial investment, but it will payoff later in the implementation phase in terms of increased productivity and quality. Other software engineers perceive modeling activity as a waste of time and money without any real contribution to the final software product. Considering present advancement of model-based software development in software industry, we are challenged to investigate the real contribution of modeling in software development. Objective: We analyze the impacts of UML modeling, specifically the production of class and sequence diagrams, on the quality of the code, as measured by defect density, and on defect resolution time. Method: Using data of a proprietary system, we conduct post-mortem analyses to test the difference in defect density between software modules that are modeled and not modeled. Similarly, we test the difference in resolution time between defects that are related to modeled and not modeled functionality. Result: We have found that the production of UML class diagrams and sequence diagrams reduces defect density in the code and the time required to fix defects. These results are obtained after controlling for the effects of co-factors such as code coupling and complexity. Conclusion: The results confirm that not only does the production of UML class diagrams and sequence diagrams possibly help improve the quality of software, but also it possibly help increase the productivity in software maintenance.     

Horizontal dispersion of software functional size with IFPUG and COSMIC units

Software development companies today are widely using software functional size measurement (FSM) as the main variable to assess the effort and time needed to perform a new software project. In the recent years, this has led to a grown interest in improving the way the measures are taken.In such sense, one of the main aspects that could have impact on measurements and that has not been enough studied is the error introduced by the measurer of the software application, through the subjectivity that can be introduced in the interpretation of the unit application rules. Such error could be evident in a measurement dispersion, defined in this paper in two possible ways: (a) Horizontal Dispersion, where the error could be introduced by the fact that two or more different people counted the same application at the same moment in the project development; and (b) Vertical Dispersion, where the error could be introduced by same measurer that count the same application at different times during the development.Since its definition by Albrecht in 1979 and its subsequent change of name in 1986, IFPUG function points have been the functional software measurement unit mostly applied, despite the definition and standardization of other variants such as NESMA, Mk-II, or more recently FiSMA. However in recent years a new method has been introduced called COSMIC that has been defined as a 2nd-generation FSM method, attracting the interest of the international software measurement community.The aim of this research is to draw some preliminary conclusions from statistical analysis of the software functional size data in which the horizontal dispersion degree could have been introduced in measurements taken into account IFPUG and COSMIC methods.     

Manual test case derivation from UML activity diagrams and state machines: A controlled experiment

ContextIt is a difficult and challenging task to fully automatize model-based testing because this demands complete and unambiguous system models as input. Therefore, in practice, test cases, especially on the system level, are still derived manually from behavioral models like UML activity diagrams or state machines. But this kind of manual test case derivation is error-prone and knowing these errors makes it possible to provide guidelines to reduce them.ObjectiveThe objective of the study presented in this paper therefore is to examine which errors are possible and actually made when manually deriving test cases from UML activity diagrams or state machines and whether there are differences between these diagram types.MethodWe investigate the errors made when deriving test cases manually in a controlled student experiment. The experiment was performed and internally replicated with overall 84 participants divided into three groups at two institutions.ResultsAs a result of our experiment, we provide a taxonomy of errors made and their frequencies. In addition, our experiment provides evidence that activity diagrams have a higher perceived comprehensibility but also a higher error-proneness than state machines with regard to manual test case derivation. This information helps to develop guidelines for manual test case derivation from UML activity diagrams and state machines.ConclusionMost errors observed were due to missing test steps, conditions or results, or content was written into the wrong field. As activity diagrams have a higher perceived comprehensibility, but also more error-prone than state machines, both diagram types are useful for manual test case derivation. Their application depends on the context and should be complemented with clear rules on how to derive test cases.     

一种顺序图的形式化描述与推理过程

以统一建模语言(UML,Unified Modeling Language)规范为基础,给出UML顺序图的形式化定义和语法描述,并进一步分析了对象消息发送和接收之间的一致性问题.最后,通过对实例推理过程的分析,对UML顺序图的特性作进一步的解释.这为基于UML顺序图的模型转换和模型验证提供了必要的前提条件,可用于对软件...