Software Engineering Laboratory Series: Collected Software Engineering Papers

The Software Engineering Laboratory (SEL) is an organization sponsored by NASA/GSFC and created to investigate the effectiveness of software engineering technologies when applied to the development of application software. The activities, findings, and recommendations of the SEL are recorded in the Software Engineering Laboratory Series, a continuing series of reports that includes this document

An Empirical investigation into metrics for object-oriented software

Object-Oriented methods have increased in popularity over the last decade, and are now the norm for software development in many application areas. Many claims were made for the superiority of object-oriented methods over more traditional methods, and these claims have largely been accepted, or at least not questioned by the software community. Such was the motivation for this thesis. One way of capturing information about software is the use of software metrics. However, if we are to have faith in the information, we must be satisfied that these metrics do indeed tell us what we need to know. This is not easy when the software characteristics we are interested in are intangible and unable to be precisely defined. This thesis considers the attempts to measure software and to make predictions regarding maintainabilty and effort over the last three decades. It examines traditional software metrics and considers their failings in the light of the calls for better standards of validation in terms of measurement theory and empirical study. From this five lessons were derived. The relatively new area of metrics for object-oriented systems is examined to determine whether suggestions for improvement have been widely heeded. The thesis uses an industrial case study and an experiment to examine one feature of objectorientation, inheritance, and its effect on aspects of maintainability, namely number of defects and time to implement a change. The case study is also used to demonstrate that it is possible to obtain early, simple and useful local prediction systems for important attributes such as system size and defects, using readily available measures rather than attempting predefined and possibly time consuming metrics which may suffer from poor definition, invalidity or inability to predict or capture anything of real use. The thesis concludes that there is empirical evidence to suggest a hypothesis linking inheritance and increased incidence of defects and increased maintenance effort and that more empirical studies are needed in order to test the hypothesis. This suggests that we should treat claims regarding the benefits of object-orientation for maintenance with some caution. This thesis also concludes that with the ability to produce, with little effort, accurate local metrics, we have an acceptable substitute for the large predefined metrics suites with their attendant problems

IDENTIFICATION AND QUANTIFICATION OF VARIABILITY MEASURES AFFECTING CODE REUSABILITY IN OPEN SOURCE ENVIRONMENT

Open source software (OSS) is one of the emerging areas in software engineering, and is gaining the interest of the software development community. OSS was started as a movement, and for many years software developers contributed to it as their hobby (non commercial purpose). Now, OSS components are being reused in CBSD (commercial purpose). However, recently, the use of OSS in SPL is envisioned recently by software engineering researchers, thus bringing it into a new arena. Being an emerging research area, it demands exploratory study to explore the dimensions of this phenomenon. Furthermore, there is a need to assess the reusability of OSS which is the focal point of these disciplines (CBSE, SPL, and OSS). In this research, a mixed method based approach is employed which is specifically 'partially mixed sequential dominant study'. It involves both qualitative (interviews) and quantitative phases (survey and experiment). During the qualitative phase seven respondents were involved, sample size of survey was 396, and three experiments were conducted. The main contribution of this study is results of exploration of the phenomenon 'reuse of OSS in reuse intensive software development'. The findings include 7 categories and 39 dimensions. One of the dimension factors affecting reusability was carried to the quantitative phase (survey and experiment). On basis of the findings, proposal for reusability attribute model was presented at class and package level. Variability is one of the newly identified attribute of reusability. A comprehensive theoretical analysis of variability implementation mechanisms is conducted to propose metrics for its assessment. The reusability attribute model is validated by statistical analysis of I 03 classes and 77 packages. An evolutionary reusability analysis of two open source software was conducted, where different versions of software are analyzed for their reusability. The results show a positive correlation between variability and reusability at package level and validate the other identified attributes. The results would be helpful to conduct further studies in this area

INFUSE Test Management

This technical report consists of the two papers discussing testing technology. INFUSE: Integration Testing with Crowd Control describes the test management facilities provided by the lNFUSE change management system. lNFUSE partially automates the construction of test harnesses and regression test suites at each level of the integration hierarchy from components available from lower levels. Adequate Testing and Object-Oriented Programming applies the axions of adequate testing to object-oriented programming languages and examines their implications. Contrary to our original expectations, we discover that in the general case classes must be retested in every context of reuse