An empirical study of package coupling in Java open-source

Excessive coupling between object-oriented classes in systems is generally acknowledged as harmful and is recognised as a maintenance problem that can result in a higher propensity for faults in systems and a „stored up‟ future problem. Characterisation and understanding coupling at different levels of abstraction is therefore important for both the project manager and developer both of whom have a vested interest in software quality. In this Thesis, coupling trends are empirically investigated over multiple versions of seven Java open-source systems (OSS). The first investigation explores the trends in longitudinal changes to open-source systems given by six coupling metrics. Coupling trends are then explored from the perspective of: the relationship between removed classes and their coupling with other classes in the same package; the relationships between coupling and 'warnings’ in packages and the time interval between versions in Java OSS; the relationship between some of these coupling metrics are also explored. Finally, the existence of an 80/20 rule for the coupling metrics is inspected. Results suggest that developer activity comprises a set of high and low periods (peak and trough‟ effect) evident as a system evolves. Findings also demonstrate that addition of coupling may have beneficial effects on a system, particularly if they are added as new functionality through the package Java feature. The fan-in and fan-out coupling metrics reveal particular features and exhibited a wide range of traits in the classes depending on their high or low values; finally, we revealed that one metric (fan-in) is the only metric that appears consistently to exhibit an 80/20 (Pareto) relationship.

Grantor dc:publisher

Brunel University, School of Information Systems, Computing and Mathematics

Year dc:date.issued

2010

Author dc:creator

• Mubarak, Asma

Advisors dc:contributor.advisor

• Counsell, S
• Hierons, RM

• Software metrics
• Evolution
• Refactoring
• Power law
• Warning

Language dc:language.iso

en

Repository record dc:identifier.uri

http://bura.brunel.ac.uk/handle/2438/4527

OAI identifier oai:identifier

oai:bura.brunel.ac.uk:2438/4527