Parastoo Mohagheghi

Object-Oriented Reading Techniques for Inspection of UML Models – An Industrial Experiment

Object-oriented design and modeling with UML has become a central part of software development in industry. Software inspections are used to cost-efficiently increase the quality of the developed software by early defect detection and correction. Several models presenting the total system need to be inspected for consistency with each other and with external documents such as requirement specifications. Special Object Oriented Reading Techniques (OORTs) have been developed to help inspectors in the individual reading step of inspection of UML models. The paper describes an experiment performed at Ericsson in Norway to evaluate the cost-efficiency of tailored OORTs in a large-scale software project. The results showed that the OORTs fit well into an incremental development process, and managed to detect defects not found by the existing reading techniques. The study demonstrated the need for further development and empirical assessment of these techniques, and for better integration with industrial work practice.

An empirical study of software change: origin, acceptance rate, and functionality vs. quality attributes

The paper presents results from an empirical study of change requests in four releases of a large-scale telecom system that is developed incrementally. The results show that earlier releases of the system are no longer evolved. Perfective changes to functionality and quality attributes are most common. Functionality is enhanced and improved in each release, while quality attributes are mostly improved, and have fewer changes in forms of new requirements. The share of adaptive/preventive changes is lower, but still not as low as reported in some previous studies. Data for corrective changes (defect fixing) have been reported by us in other studies. The project organization initiates most change requests, rather than customers or changing environments. The releases show an increasing tendency to accept change requests, which normally impact project plans. Changes related to functionality and quality attributes seem to have similar acceptance rates. We did not identify any significant difference between the change-proneness of reused and non-reused components.

A Study of Developer Attitude to Component Reuse in Three IT Companies

Incremental development, software reuse, product families and component-based development seem to be the potent technologies to achieve benefits in productivity, quality and maintainability, and to reduce the risks of changes. These approaches have multiple and crosscutting impacts on development practices and quality attributes. Empirical studies in industry answer questions about why and when certain approaches are chosen, how these are applied with impact on single instances and how to generalize over classes or systems. Large, long-lived systems place more demands on software engineering approaches. Complexity is increased, systems should have the correct subset of functionality and be maintainable for several years to return the investment.The research in this thesis is based on several empirical studies performed at Ericsson in Grimstad, Norway and in the context of the Norwegian INCO project (INcremental and COmponent-Based Software Development). A product family with two large-scale products that have been developed incrementally is described. The work aimed to assess the impact of development approaches on quality and improve the practice in some aspects. The research has been a mixed-method design and the studies use qualitative data collected from sources such as web pages, text documents and own studies, as well as quantitative data from company’s data repositories for several releases of one product. The thesis contains five main novel contributions:C1. Empirical verification of reuse benefits. Quantitative analyses of defect reports, change requests and component size showed reuse benefits in terms of lower defect-density, higher stability between releases, and no significant difference in change-proneness between reused and non-reused components.C2. Increased understanding of the origin and type of changes in requirements in each release and changes of software between releases. A quantitative analysis of change requests showed that most changes are initiated by the organization. Perfective changes to functionality and quality attributes are most common. Functionality is enhanced and improved in each release, while quality attributes are mostly improved and have fewer changes in form of new requirements.C3. Developing an effort estimation method using use case specifications and the distribution of effort in different phases of incremental software development. The estimation method is tailored for complex use case specifications, incremental changes in these and reuse of software from previous releases. Historical data on effort spent in two releases are used to calibrate and validate the method.C4. Identifying metrics for a combination of reuse of software components and incremental development. Results of quantitative and qualitative studies are used to relate quality attributes to development practices and approaches, and to identify metrics for a combination of software reuse and incremental development.C5. Developing a data mining method for exploring industrial data repositories based on experience from the quantitative studies. This thesis also proposes how to improve the software processes for incremental development of product families. These are considered minor contributions:C6a. Adaptation of the Rational Unified Process for reuse to improve consistency between practice and the software process model.C6b. Improving techniques for incremental inspection of UML models to improve the quality of components. A controlled industrial experiment is performed.