Antony Tang

A rationale-based architecture model for design traceability and reasoning

Large systems often have a long life-span and comprise many intricately related elements. The verification and maintenance of these systems require a good understanding of their architecture design. Design rationale can support such understanding but it is often undocumented or unstructured. The absence of design rationale makes it much more difficult to detect inconsistencies, omissions and conflicts in an architecture design. We address these issues by introducing a rationale-based architecture model that incorporates design rationale, design objects and their relationships. This model provides reasoning support to explain why design objects exist and what assumptions and constraints they depend on. Based on this model, we apply traceability techniques for change impact analysis and root-cause analysis, thereby allowing software architects to better understand and reason about an architecture design. In order to align closely with industry practices, we choose to represent the rationale-based architecture model in UML. We have implemented a tool-set to support the capture and the automated tracing of the model. As a case study, we apply this approach to an real-world electronic payment system.

A survey of architecture design rationale

Many claims have been made about the consequences of not documenting design rationale. The general perception is that designers and architects usually do not fully understand the critical role of systematic use and capture of design rationale. However, there is to date little empirical evidence available on what design rationale mean to practitioners, how valuable they consider it, and how they use and document it during the design process. This paper reports a survey of practitioners to probe their perception of the value of design rationale and how they use and document the background knowledge related to their design decisions. Based on 81 valid responses, this study has discovered that practitioners recognize the importance of documenting design rationale and frequently use them to reason about their design choices. However, they have indicated barriers to the use and documentation of design rationale. Based on the findings, we conclude that further research is needed to develop methodology and tool support for design rationale capture and usage. Furthermore, we put forward some specific research questions about design rationale that could be further investigated to benefit industry practice.

A comparative study of architecture knowledge management tools

Recent research suggests that architectural knowledge, such as design decisions, is important and should be recorded alongside the architecture description. Different approaches have emerged to support such architectural knowledge (AK) management activities. However, there are different notions of and emphasis on what and how architectural activities should be supported. This is reflected in the design and implementation of existing AK tools. To understand the current status of software architecture knowledge engineering and future research trends, this paper compares five architectural knowledge management tools and the support they provide in the architecture life-cycle. The comparison is based on an evaluation framework defined by a set of 10 criteria. The results of the comparison provide insights into the current focus of architectural knowledge management support, their advantages, deficiencies, and conformance to the current architectural description standard. Based on the outcome of this comparison a research agenda is proposed for future work on AK tools.

A comparative analysis of architecture frameworks

Architecture frameworks are methods used in architecture modeling. They provide a structured and systematic approach to designing systems. To date there has been little analysis on their roles in system and software engineering and if they are satisfactory. This study provides a model of understanding through analyzing the goals, inputs and outcomes of six architecture frameworks. It characterizes two classes of architecture frameworks and identifies some of their deficiencies. To overcome these deficiencies, we propose to use costs, benefits and risks for architecture analysis. We also propose a method to delineate architecture activities from detailed design activities.

Collision avoidance timing analysis of DSRC-based vehicles

Dedicated short-range communication (DSRC) has been used in prototyped vehicles to test vehicle-to-vehicle communication for collision avoidance. However, there is little study on how collision avoidance software should behave to best mitigate accident collisions. In this paper, we analyse the timing of events and how they influence software-based collision avoidance strategies. We have found that the warning strategies for collision avoidance are constrained by the timing of events such as DSRC communication latency, detection range, road condition, driver reaction and deceleration rate. With these events, we define two collision avoidance timings: critical time to avoid collision and preferred time to avoid collision, and they dictate the design of software-based collision avoidance systems.

A Survey of the Use and Documentation of Architecture Design Rationale

Many claims have been made about the problems caused by not documenting design rationale. The general perception is that designers and architects usually do not fully understand the critical role of systematic use and capture of design rationale. However, there is to date little empirical evidence available on what design rationale mean to practitioners, how valuable they consider them, and how they use and document design rationale during the design process. This paper reports an empirical study that surveyed practitioners to probe their perception of the value of design rationale and how they use and document background knowledge related to their design decisions. Based on eighty-one valid responses, this study has discovered that practitioners recognize the importance of documenting design rationale and frequently use them to reason about their design choices. However, they have indicated barriers to the use and documentation of design rationale. Based on the findings, we conclude that much research is needed to develop methodology and tool support for design rationale capture and usage. Furthermore, we put forward some research questions that would benefit from further investigation into design rationale in order to support practice in industry.

Using Bayesian belief networks for change impact analysis in architecture design

Research into design rationale in the past has focused on argumentation-based design deliberations. These approaches cannot be used to support change impact analysis effectively because the dependency between design elements and decisions are not well represented and cannot be quantified. Without such knowledge, designers and architects cannot easily assess how changing requirements and design decisions may affect the system. In this article, we introduce the Architecture Rationale and Element Linkage (AREL) model to represent the causal relationships between architecture design elements and decisions. We apply Bayesian Belief Networks (BBN) to AREL, to capture the probabilistic causal relationships between design elements and decisions. We employ three different BBN-based reasoning methods to analyse design change impact: predictive reasoning, diagnostic reasoning and combined reasoning. We illustrate the application of the BBN modelling and change impact analysis methods by using a partial design of a real-world cheque image processing system. To support its implementation, we have developed a practical, integrated tool set for the architects to use.

Software Architecture Design Reasoning: A Case for Improved Methodology Support

This paper presents the capturing and recording of reasoning behind software architecture design to encourage architects to more carefully consider design decisions and better support future maintenance.

Knowledge-based approaches in software documentation: A systematic literature review

Context: Software documents are core artifacts produced and consumed in documentation activity in the software lifecycle. Meanwhile, knowledge-based approaches have been extensively used in software development for decades, however, the software engineering community lacks a comprehensive understanding on how knowledge-based approaches are used in software documentation, especially documentation of software architecture design. Objective: The objective of this work is to explore how knowledge-based approaches are employed in software documentation, their influences to the quality of software documentation, and the costs and benefits of using these approaches. Method: We use a systematic literature review method to identify the primary studies on knowledge-based approaches in software documentation, following a pre-defined review protocol. Results: Sixty studies are finally selected, in which twelve quality attributes of software documents, four cost categories, and nine benefit categories of using knowledge-based approaches in software documentation are identified. Architecture understanding is the top benefit of using knowledge-based approaches in software documentation. The cost of retrieving information from documents is the major concern when using knowledge-based approaches in software documentation. Conclusions: The findings of this review suggest several future research directions that are critical and promising but underexplored in current research and practice: (1) there is a need to use knowledge-based approaches to improve the quality attributes of software documents that receive less attention, especially credibility, conciseness, and unambiguity; (2) using knowledge-based approaches with the knowledge content in software documents which gets less attention in current applications of knowledge-based approaches in software documentation, to further improve the practice of software documentation activity; (3) putting more focus on the application of software documents using the knowledge-based approaches (knowledge reuse, retrieval, reasoning, and sharing) in order to make the most use of software documents; and (4) evaluating the costs and benefits of using knowledge-based approaches in software documentation qualitatively and quantitatively.

Design Reasoning Improves Software Design Quality

Making justifiable decisions is a critical aspect of software architec-ture design. However, there has been limited empirical research on the effects of design reasoning on the quality of software design. The goal of this work is to investigate if there is any quality improvement to software design when design reasoning is applied. We conducted an empirical study involving twenty designers, the designers were asked to design a user interface and their designs were scored and compared. The results showed that the test group that was equipped with design reasoning produced a higher quality design than the control group, especially for inexperienced designers.