International Journal of Software Engineering and Knowledge Engineering

Software planning is very important for the success of a software project. Even if the same developers work on the same project, the time span of the project and the quality of software may change based on the project plan. When software managers plan a software project, they strive to allocate human resources in a more efficient way to produce a better software with less cost. The planning process is, however, time-consuming and complicated, especially when the size of the software project is large.

Many approaches have been proposed to help software project managers by providing optimal human resource allocations in terms of minimizing the cost. Previous approaches, however, only concentrated on minimizing the cost, and no existing works have considered the practical issues affecting project schedules in practice.

We elicited the practical considerations relating to the human resource allocation problem through discussions with a group of software project experts. The practical considerations can affect the project schedule in practice, but their importance has not been taken into consideration in previous approaches. Reflecting the practical considerations, we propose an approach for solving the human resource allocation problem using a genetic algorithm (GA).

We compare our approach to an approach that only considers minimization of the time span. Our evaluation shows that the proposed algorithm considers the practical considerations well, in terms of continuous allocation on relevant tasks, minimization of developer multitasking time, and balance of allocation. We also conducted a survey targeting software developers and managers, and the responses showed that practical considerations are as important as minimizing the cost, and our approach would be helpful to software managers. We also investigate the effect of weight factors and coefficient between sub-scores, and find that it is difficult to consider some practical considerations at the same time.

Although the Earned Value Management (EVM) technique has been used by several companies in various industrial sectors (software development, construction, aerospace, aeronautics, among others) for over 35 years to predict time and cost outcomes, many studies have found vulnerabilities, including: (i) cost performance data do not always have normal distribution, which makes reliable projections difficult; (ii) instability of cost performance indexes during the execution of projects, (iii) there is a worsening tendency in cost performance indexes when project approaches termination. This paper proposes an extension of the EVM technique through the integration of historical cost performance data of processes as a means to improve the project's cost predictability. The proposed technique was evaluated through an empirical study, which evaluated the implementation of the proposed technique in 22 software development projects. The proposed technique has been applied in real projects with the aim of evaluating the accuracy and variation compared to the traditional technique. Hypotheses tests with 95% significance level were performed, and the proposed technique was more accurate and more precise than the traditional technique for calculating the Cost Performance Index (CPI) and Estimates at Completion (EAC).

In this paper, we present Dominoes, an approach for analyzing software repositories with thousands of artifacts by considering multiple perspectives of the software development data. In order to achieve computational power we model the data and its relationships as matrices, making possible to efficiently process them with a GPUs (Graphics Processing Unit) based architectures. Dominoes can support automated exploration of different relationships among project artifacts, where users have the flexibility to interactively combine and compose them. Our solution organizes data extracted from software repositories into multiple matrices that can be treated as domino pieces (e.g. [commit|method]). The connection of such pieces corresponds to a set of matrices operations, which derive additional domino pieces. These derived domino pieces represent specific project entity relationships (e.g. number of commits in which two methods co-occurred) and can be used for further explorations. As an evaluation of the Dominoes framework we present two exploratory case studies based on Apache Derby. First, we use Dominoes to show how dependencies among artifacts can be derived. Then, we identify expertise of developers by considering the commits that developers make to artifacts. We show that identifying relationships among 34,335 elements along 7,578 commits takes about 0.2 minutes in GPU, while the same processing in CPU takes about 413 minutes. Besides, identifying expertise of developer on a set of 34,335 files and 36 developers takes about 0.1 minute in GPU, whereas in CPU it takes 324 minutes.

Software Product Line Engineering (SPLE) is a systematic reuse approach to develop a short time-to-market and quality products, called Software Product Line (SPL). Usually, a SPL is not developed from scratch but it is developed by reusing features (resp. their implementing source code elements) of existing similar systems previously developed by ad-hoc reuse techniques. The features implementations that are reused may be changed for developing new products (SPL) using SPLE. Any code element can be a part of (shared by) different features implementations; modifying one feature's implementation can thus impact others. Therefore, feature-level Change Impact Analysis (CIA) is important to predict affected features for change management purpose. In this paper, we propose a feature-level CIA approach using Formal Concept Analysis (FCA) applied to SPL evolution. In our experimental evaluation using three case studies of different domains and sizes, we show the effectiveness of our technique in terms of the most commonly used metrics on the subject.

The basic measurements for software quality control and management are the various project and software metrics collected at various states of a software development life cycle. The software metrics may not all be relevant for predicting the fault proneness of software components, modules, or releases. Thus creating the need for the use of feature (software metric) selection. The goal of feature selection is to find a minimum subset of attributes that can characterize the underlying data with results as well as, or even better than the original data when all available features are considered. As an example of inter-disciplinary research (between data science and software engineering), this study is unique in presenting a large comparative study of wrapper-based feature (or attribute) selection techniques for building defect predictors. In this paper, we investigated thirty wrapper-based feature selection methods to remove irrelevant and redundant software metrics used for building defect predictors. In this study, these thirty wrappers vary based on the choice of search method (Best First or Greedy Stepwise), leaner (Naïve Bayes, Support Vector Machine, and Logistic Regression), and performance metric (Overall Accuracy, Area Under ROC (Receiver Operating Characteristic) Curve, Area Under the Precision-Recall Curve, Best Geometric Mean, and Best Arithmetic Mean) used in the defect prediction model evaluation process. The models are trained using the three learners and evaluated using the five performance metrics. The case study is based on software metrics and defect data collected from a real world software project.

The results demonstrate that Best Arithmetic Mean is the best performance metric used within the wrapper. Naïve Bayes performed significantly better than Logistic Regression and Support Vector Machine as a wrapper learner on slightly and less imbalanced datasets. We also recommend Greedy Stepwise as a search method for wrappers. Moreover, comparing to models built with full datasets, the performances of defect prediction models can be improved when metric subsets are selected through a wrapper subset selector.

Defect prediction is very challenging in software development practice. Classification models are useful tools that can help for such prediction. Classification models can classify program modules into quality-based classes, e.g. fault-prone (fp) or not-fault-prone (nfp). This facilitates the allocation of limited project resources. For example, more resources are assigned to program modules that are of poor quality or likely to have a high number of faults based on the classification. However, two main problems, high dimensionality and class imbalance, affect the quality of training datasets and therefore classification models. Feature selection and data sampling are often used to overcome these problems. Feature selection is a process of choosing the most important attributes from the original dataset. Data sampling alters the dataset to change its balance level. Another technique, called boosting (building multiple models, with each model tuned to work better on instances misclassified by previous models), is found to also be effective for resolving the class imbalance problem.

In this study, we investigate an approach for combining feature selection with this ensemble learning (boosting) process. We focus on two different scenarios: feature selection performed prior to the boosting process and feature selection performed inside the boosting process. Ten individual base feature ranking techniques, as well as an ensemble ranker based on the ten, are examined and compared over the two scenarios. We also employ the boosting algorithm to construct classification models without performing feature selection and use the results as the baseline for further comparison. The experimental results demonstrate that feature selection is important and needed prior to the learning process. In addition, the ensemble feature ranking method generally has better or similar performance than the average of the base ranking techniques, and more importantly, the ensemble method exhibits better robustness than most base ranking techniques. As for the two scenarios, the results show that applying feature selection inside boosting performs better than using feature selection prior to boosting.

Today more and more information on the Web makes it difficult to get domain-specific information due to the huge amount of data sources and the keywords that have few features. Anchor texts, which contain a few features of a specific topic, play an important role in domain-specific information retrieval, especially in Web page classification. However, the features contained in anchor texts are not informative enough. This paper presents a novel incremental method for Web page classification enhanced by link-contexts and clustering. Directly applying the vector of anchor text to a classifier might not get a good result because of the limited amount of features. Link-context is used first to obtain the contextual information of the anchor text. Then, a hierarchical clustering method is introduced to cluster feature vectors and content unit, which increases the length of a feature vector belonging to one specific class. Finally, incremental SVM is proposed to get the final classifier and increase the accuracy and efficiency of a classifier. Experimental results show that the performance of our proposed method outperforms the conventional topical Web crawler in Harvest rate and Target recall.

It has been estimated that about 2% of global carbon dioxide emissions can be attributed to IT systems. Green (or sustainable) computing refers to supporting business critical computing needs with the least possible amount of power. This phenomenon changes the priorities in the design of new software systems and in the way companies handle existing ones. In this paper, we present the results of a research project aimed to develop a migration strategy to give an existing software system a new and more eco-sustainable lease of life. We applied a strategy for migrating a subject system that performs intensive and massive computation to a target architecture based on a Graphics Processing Unit (GPU). We validated our solution on a system for path finding robot simulations. An analysis on execution time and energy consumption indicated that: (i) the execution time of the migrated system is less than the execution time of the original system; and (ii) the migrated system reduces energy waste, so suggesting that it is more eco-sustainable than its original version. Our findings improve the body of knowledge on the effect of using the GPU in green computing.