Hongyu Pei Breivold

A systematic review of software architecture evolution research

Context: Software evolvability describes a software systems 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.

Component-Based and Service-Oriented Software Engineering: Key Concepts and Principles

Component-based software engineering (CBSE) and service-oriented software engineering (SOSE) are two of the most dominant engineering paradigms in current software community and industry. Although they have continued their development tracks in parallel and have different focus, both paradigms have similarities in many senses, which also have resulted in confusion in understanding and applying similar concepts or the same concepts designated differently. In this paper, we present a comparison analysis framework of CBSE and SOSE and analyze them from a variety of perspectives. We discuss as well the possibility of combining the strengths of the two paradigms to meet non-functional requirements. The contribution of this paper is to clarify the characteristics of CBSE and SOSE, shorten the gap between them and bring the two worlds together so that researchers and practitioners become aware of essential issues of both paradigms, which may serve as inputs for further utilizing them in a reasonable and complementary way.

What Does Research Say about Agile and Architecture

Agile has been used to refer to a software development paradigm that emphasizes rapid and flexible development. In the meanwhile, we have through our practical experiences in scaling up agile methods, noticed that architecture plays an important role. Due to the inter-relationship between agile methods and architecture, as well as divergent perceptions on their correlation stated in numerous sources, we are motivated to find out how these perceptions are supported by findings in the research community in general and in empirical studies in particular. To fully benefit from agile practices and architectural disciplines, we need empirical data on the perceived and experienced impacts of introducing agile methods to existing software development process, as well as correlations between agile and architecture. In this paper, we survey the research literature for statements made regarding the relationship between agile development and software architecture. The main findings are that there is a lack of scientific support for many of the claims that are concerned with agile and architecture, and more empirical studies are needed to fully reveal the benefits and drawbacks implied by an agile software development method.

Analyzing Software Evolvability

Software evolution is characterized by inevitable changes of software and increasing software complexities, which in turn may lead to huge costs unless rigorously taking into account change accommodations. This is in particular true for long-lived systems in which changes go beyond maintainability. For such systems, there is a need to address evolvability explicitly during the entire lifecycle. Nevertheless, there is a lack of a model that can be used for analyzing, evaluating and comparing software systems in terms of evolvability. In this paper, we describe the initial establishment of an evolvability model as a framework for analysis of software evolvability. We motivate and exemplify the model through an industrial case study of a software-intensive automation system.

Migrating Industrial Systems towards Software Product Lines: Experiences and Observations through Case Studies

Software product line engineering has emerged as one of the dominant paradigms for developing variety of software products based on a shared platform and shared software artifacts. An important and challenging type of software maintenance and evolution is how to cost-effectively manage the migration of legacy systems towards product lines. This paper presents a structured migration method and describes our experiences in migrating industrial legacy systems into product lines. In addition, we present a number of specific recommendations for the transition process which will be of value to organizations that are considering a product line approach to their business. The recommendations cover four perspectives: business, organization, product development processes and technology.

Using dependency model to support software architecture evolution

Evolution of software systems is characterized by inevitable changes of software and increasing software complexity, which in turn may lead to huge maintenance and development costs. For long-lived systems, there is a need to address and maintain evolvability (i.e. a systempsilas ability to easily accommodate changes) during the entire lifecycle. As designing software for ease of extension and contraction depends on how well the software structure is organized, this paper explores the relationships between evolvability, modularity and inter-module dependency. Through a case study of an industrial power control and protection system, we describe our work in managing its software architecture evolution, guided by the dependency analysis at the architectural level. The paper includes also the main analysis results, our experiences and reflections during the dependency analysis process in the case study.

Internet of Things for Industrial Automation -- Challenges and Technical Solutions

Using internet of things (IoT) to connect things, service, and people for intelligent operations has been discussed and deployed in many industry domains such as smart city, smart energy, healthcare, food and water tracking, logistics and retail, and transportation. However, scarce information is available for IoT usage in industrial automation domain for reliable and collaborative automation with respect to e.g., enabling scalable collaboration between heterogeneous devices and systems, offering predictable and fault-tolerant real-time closed-loop control, and inclusion of intelligent service features from edge devices to the cloud. In this paper, we will clarify the specific quality attribute constraints within industrial automation, present specific industrial IoT challenges due to these constraints, and discuss the potentials of utilizing some technical solutions to cope with these challenges.

Scalability and Robustness of Time-Series Databases for Cloud-Native Monitoring of Industrial Processes

Todays industrial control systems store large amounts of monitored sensor data in order to optimize industrial processes. In the last decades, architects have designed such systems mainly under the assumption that they operate in closed, plant-side IT infrastructures without horizontal scalability. Cloud technologies could be used in this context to save local IT costs and enable higher scalability, but their maturity for industrial applications with high requirements for responsiveness and robustness is not yet well understood. We propose a conceptual architecture as a basis to designing cloud-native monitoring systems. As a first step we benchmarked three open source time-series databases (OpenTSDB, KairosDB and Databus) on cloud infrastructures with up to 36 nodes with workloads from realistic industrial applications. We found that at least KairosDB fulfills our initial hypotheses concerning scalability and reliability.

A Systematic Review of Studies of Open Source Software Evolution

Software evolution relates to how software systems evolve over time. With the emergence of the open source paradigm, researchers are provided with a wealth of data for open source software evolution analysis. In this paper, we present a systematic review of open source software (OSS) evolution. The objective of this review is to obtain an overview of the existing studies in open source software evolution, with the intention of achieving an understanding of how software evolvability (i.e., a software system’s ability to easily accommodate changes) is addressed during development and evolution of open source software. The primary studies for this review were identified based on a pre-defined search strategy and a multi-step selection process. Based on their research topics, we have identified four main categories of themes: software trends and patterns, evolution process support, evolvability characteristics addressed in OSS evolution, and examining OSS at software architecture level. A comprehensive overview and synthesis of these categories and related studies is presented as well.

A Systematic Review on Architecting for Software Evolvability

For long-lived systems, there is a need to address evolvability (i.e. a system’s ability to easily accommodate changes) explicitly during the entire lifecycle. In this paper, we undertake a systematic review to obtain an overview of the existing studies in promoting software evolvability at architectural level. The search strategy identified 58 studies that were catalogued as primary studies for this review after using multi-step selection process. The studies are classified into five main categories of themes, including techniques that support quality considerations during software architecture design, architectural quality evaluation, economic valuation, architectural knowledge management and modeling techniques. The review investigates what is currently known about architecting software evolvability at architecture level. Implications for research and practice are presented.