A systematic review of software architecture evolution research

Context

Software evolvability describes a software system’s ability to easily accommodate future changes. It is a fundamental characteristic for making strategic decisions, and increasing economic value of software. For long-lived systems, there is a need to address evolvability explicitly during the entire software lifecycle in order to prolong the productive lifetime of software systems. For this reason, many research studies have been proposed in this area both by researchers and industry practitioners. These studies comprise a spectrum of particular techniques and practices, covering various activities in software lifecycle. However, no systematic review has been conducted previously to provide an extensive overview of software architecture evolvability research.

Objective

In this work, we present such a systematic review of architecting for software evolvability. The objective of this review is to obtain an overview of the existing approaches in analyzing and improving software evolvability at architectural level, and investigate impacts on research and practice.

Method

The identification of the primary studies in this review was based on a pre-defined search strategy and a multi-step selection process.

Results

Based on research topics in these studies, we have identified five main categories of themes: (i) techniques supporting quality consideration during software architecture design, (ii) architectural quality evaluation, (iii) economic valuation, (iv) architectural knowledge management, and (v) modeling techniques. A comprehensive overview of these categories and related studies is presented.

Conclusion

The findings of this review also reveal suggestions for further research and practice, such as (i) it is necessary to establish a theoretical foundation for software evolution research due to the fact that the expertise in this area is still built on the basis of case studies instead of generalized knowledge; (ii) it is necessary to combine appropriate techniques to address the multifaceted perspectives of software evolvability due to the fact that each technique has its specific focus and context for which it is appropriate in the entire software lifecycle.     

Software performance tuning of software product family architectures: Two case studies in the real-time embedded systems domain

Software performance is an important non-functional quality attribute and software performance evaluation is an essential activity in the software development process. Especially in embedded real-time systems, software design and evaluation are driven by the needs to optimize the limited resources, to respect time deadlines and, at the same time, to produce the best experience for end-users. Software product family architectures add additional requirements to the evaluation process. In this case, the evaluation includes the analysis of the optimizations and tradeoffs for the whole products in the family. Performance evaluation of software product family architectures requires knowledge and a clear understanding of different domains: software architecture assessments, software performance and software product family architecture. We have used a scenario-driven approach to evaluate performance and dynamic memory management efficiency in one Nokia software product family architecture. In this paper we present two case studies. Furthermore, we discuss the implications and tradeoffs of software performance against evolvability and maintenability in software product family architectures.     

Decision support for moving from a single product to a product portfolio in evolving software systems

Successful software systems continuously evolve to accommodate ever-changing needs of customers. Accommodating the feature requests of all the customers in a single product increases the risks and costs of software maintenance. A possible approach to mitigate these risks is to transition the evolving software system (ESS) from a single system to a portfolio of related product variants, each addressing a specific customers’ segment. This evolution should be conducted such that the extent of modifications required in ESS's structure is reduced. The proposed method COPE+ uses preferences of customers on product features to generate multiple product portfolios each containing one product variant per segment of customers. Recommendations are given to the decision maker to update the product portfolios based on structural analysis of ESS. Product portfolios are compared with the ESS using statechart representations to identify the level of similarity in their behaviors. A proof of concept is presented by application to an open-source text editing system. Structural and behavioral analysis of candidate portfolios helped the decision maker to select one portfolio out of three candidates.     

Determining factors that affect long-term evolution in scientific application software

One of the characteristics of scientific application software is its long lifetime of active maintenance. There has been little software engineering research into the development characteristics of scientific software and into the factors that support its successful long evolution. The research described in this paper introduces a novel model to examine the nature of change that influenced an example of industrial scientific software over its lifetime. The research uses the model to provide an objective analysis of factors that contributed to long-term evolution of the software system. Conclusions suggest that the architectural design of the software and the characteristics of the software development group played a major role in the successful evolution of the software. The novel model of change and the research method developed for this study are independent of the type of software under study.     

A systematic review of evaluation of variability management approaches in software product lines

Context

Variability management (VM) is one of the most important activities of software product-line engineering (SPLE), which intends to develop software-intensive systems using platforms and mass customization. VM encompasses the activities of eliciting and representing variability in software artefacts, establishing and managing dependencies among different variabilities, and supporting the exploitation of the variabilities for building and evolving a family of software systems. Software product line (SPL) community has allocated huge amount of effort to develop various approaches to dealing with variability related challenges during the last two decade. Several dozens of VM approaches have been reported. However, there has been no systematic effort to study how the reported VM approaches have been evaluated.

Objective

The objectives of this research are to review the status of evaluation of reported VM approaches and to synthesize the available evidence about the effects of the reported approaches.

Method

We carried out a systematic literature review of the VM approaches in SPLE reported from 1990s until December 2007.

Results

We selected 97 papers according to our inclusion and exclusion criteria. The selected papers appeared in 56 publication venues. We found that only a small number of the reviewed approaches had been evaluated using rigorous scientific methods. A detailed investigation of the reviewed studies employing empirical research methods revealed significant quality deficiencies in various aspects of the used quality assessment criteria. The synthesis of the available evidence showed that all studies, except one, reported only positive effects.

Conclusion

The findings from this systematic review show that a large majority of the reported VM approaches have not been sufficiently evaluated using scientifically rigorous methods. The available evidence is sparse and the quality of the presented evidence is quite low. The findings highlight the areas in need of improvement, i.e., rigorous evaluation of VM approaches. However, the reported evidence is quite consistent across different studies. That means the proposed approaches may be very beneficial when they are applied properly in appropriate situations. Hence, it can be concluded that further investigations need to pay more attention to the contexts under which different approaches can be more beneficial.