Jan Verelst

Refactoring - improving coupling and cohesion of existing code

Refactorings are widely recognised as ways to improve the internal structure of object-oriented software while maintaining its external behaviour. Unfortunately, refactorings concentrate on the treatment of symptoms (the so called code-smells), thus improvements depend a lot on the skills of the maintained coupling and cohesion on the other hand are quality attributes which are generally recognized as being among the most likely quantifiable indicators for software maintainability. Therefore, this paper analyzes how refactorings manipulate coupling/cohesion characteristics, and how to identify refactoring opportunities that improve these characteristics. As such we provide practical guidelines for the optimal usage of refactoring in a software maintenance process.

Should You Adopt Open Source Software

Many organizations use open source infrastructure software such as Linux, and open source software (OSS) is generally considered a viable technology. Both professional and academic literature devote much attention to the OSS phenomenon. However, decision makers considering the adoption of OSS face a plethora of books, research papers, and articles highlighting OSSs advantages and disadvantages. Different articles attach different levels of importance to these advantages or factors related to the adoption decision. Reasons for adopting OSS vary from the pragmatic. Organizations must consider the advantages and disadvantages of open source software before adopting it.

The discipline of enterprise engineering

A century ago, Taylor published a landmark in the organisational sciences: his Principles of Scientific Management. Many researchers have elaborated on Taylor’s principles, or have been influenced otherwise. The authors of the current paper evaluate a century of enterprise development, and conclude that a paradigm shift is needed for dealing adequately with the challenges that modern enterprises face. Three generic goals are identified. The first one, intellectual manageability, is the basis for mastering complexity; current approaches fall short in assisting professionals to master the complexity of enterprises and enterprise changes. The second goal, organisational concinnity, is conditional for making strategic initiatives operational; current approaches do not, or inadequately, address this objective. The third goal, social devotion, is the basis for achieving employee empowerment as well as knowledgeable management and governance; modern employees are highly educated knowledge workers; yet, the mindset of managers has not evolved accordingly. The emerging discipline of Enterprise Engineering, as conceived by the authors, is considered to be a suitable vehicle for achieving these goals. It does so by providing new, powerful theories and effective methodologies. A theoretical framework is presented for positioning the theories, goals, and fundamentals of enterprise engineering in four classes: philosophical, ontological, ideological and technological.

Towards evolvable software architectures based on systems theoretic stability

In todays increasingly volatile environments, evolvability is quickly becoming the most desirable characteristic of information systems. Current information systems still struggle to provide these high levels of evolvability. Based on the concept of stability from systems theory, we require that information systems should be stable with respect to a set of anticipated changes in order to exhibit high evolvability. This requires that information systems should be free from so‐called combinatorial effects. Combinatorial effects occur when the impact of a change is dependent on the size of the information system. To eliminate these combinatorial effects, we propose four theorems that are constraints on the modular structure of software architectures. The theorems are prescriptive and ensure that stable information systems are built, thereby guaranteeing high evolvability. We further present five higher level modular structures called elements. These elements provide the core functionality of information systems and comply fully with the stringent constraints implied by the four theorems. The internal structure of these elements is described by design patterns which are eligible for automatic code generation. These design patterns offer a constructive proof that it is possible to build information systems in practice by applying this set of theorems. Copyright

The transformation of requirements into software primitives: Studying evolvability based on systems theoretic stability

Evolvability is widely considered to be a crucial characteristic of software architectures, particularly in the area of information systems. Although many approaches have been proposed for improving evolvability, most indications are that it remains challenging to deliver the required levels of evolvability. In this paper, we present a theoretical approach to how the concept of systems theoretic stability can be applied to the evolvability of software architectures of information systems. We define and formalize the transformation of a set of basic functional requirements into a set of instantiations of software constructs. We define this transformation using both a static and a dynamic perspective. In the latter perspective, we formulate the postulate that information systems should be stable against new requirements. Based on this postulate, we derive a number of design theorems for software implementation. Using this transformation we use theoretical arguments to derive that these theorems contribute to achieving stability.

Techniques for Modeling Workflows and Their Support of Reuse

Several authors propose their own technique based on Petri Nets to model workflow processes. Most of them recognise the adaptability problem inherent to workflows, viz. the frequently and/or radically changing character due to changing business process rules, but suggest totally different solutions. Because the proposed techniques are fundamentally different, eleven of these techniques are briefly discussed and compared. Next, we survey approaches to reuse in the workflow field and we classify them in a framework derived from the information systems literature.

The Impact of Ideology on the Organizational Adoption of Open Source Software

Previous research has shown that the open source movement shares a common ideology. Employees belonging to the open source movement often advocate the use of open source software within their organization. Hence, their belief in the underlying open source software ideology may influence the decision making on the adoption of open source software. This may result in an ideological—rather than pragmatic—decision. A recent study has shown that American organizations are quite pragmatic in their adoption decision. We argue that there may be circumstances in which there is more opportunity for ideological behavior. We therefore investigated the organizational adoption decision in Belgian organizations. Our results indicate that most organizations are pragmatic in their decision making. However, we have found evidence that suggests that the influence of ideology should not be completely disregarded in small organizations.

Does the "Refactor to Understand" reverse engineering pattern improve program comprehension?

Program comprehension is a fundamental requirement for all but the most trivial maintenance activities. Previous research has demonstrated key principles for improving comprehension. Among others, these consist of the introduction of beacons as indexes into knowledge, and the chunking of low-level structures into higher-level abstractions. These principles are naturally reflected in the reverse engineering pattern Refactor to Understand, which uses incremental renaming and extracting of program elements as the means to decipher cryptic code. In this paper, we discuss a controlled experiment to explore differences in program comprehension between the application of Refactor to Understand and the traditional Read to Understand pattern. Our results support added value of Refactor to Understand regarding specific aspects of program comprehension and specific types of source code. These findings illustrate the need for further experiments to provide clear guidelines on the application of refactorings for improving program comprehension.

The Organizational Adoption of Open Source Server Software by Belgian Organizations

This study reports on five case studies in Belgian organizations that currently use open source server software. Respondents were asked about their motivation to use open source server software. Our results indicate that the lower cost, high reliability and availability of external support are the prime reasons why organizations use open source software. The often claimed advantage of open source software of having access to the source code was found relevant only for those organizations who perform development based on open source software. Some factors that were found relevant in previous studies (such as the support of standards) were however deemed less important by the organizations in our sample.

The Importance of External Support in the Adoption of Open Source Server Software

IT managers seem to be hesitant to adopt OSS in the absence of professional support. Previous qualitative studies have indeed suggested that the availability of external support is important for the adoption of OSS. Therefore, we feel it is interesting to gain more insight into the role of external support in the adoption process. To this end, we performed a web survey involving 95 Belgian organizations. Our data suggests a balanced picture. As expected, our results show that the majority of organizations in our sample rely on commercial support such as vendor or third party support. Even organizations that have deployed OSS to a large extent—and that are therefore likely to have some experience and familiarity with OSS—rely on commercial support. Nevertheless, a considerable proportion of organizations indicated not to rely on commercial support, which suggests that internal expertise can be sufficient for successful adoption. Finally, and most surprisingly, we have found that the OSS community is used by a large proportion of organizations. This indicates that the OSS community is a valuable source of external support for organizations. Nevertheless, it appears that it is primarily used by organizations with a rather strong background in IT.