Two controlled experiments on model-based architectural decision making

ContextIn recent years, architectural design decisions are becoming more and more common for documenting software architectures. Rather than describing the structure of software systems, architectural decisions capture the design rationale and – often reusable – architectural knowledge. Many approaches and tools have been proposed in the literature to support architectural decision making and documentation (for instance, based on models, ontologies, or templates). In this context, the capturing, organization, and effective reuse of architectural knowledge has gained a lot of attention.ObjectiveHowever, there is little empirical evidence about the supportive effect of reusable architectural knowledge on the effectiveness and efficiency of architectural decision making.MethodTo investigate these aspects, we conducted two separate controlled experiments with software architecture students in which we tested the supportive effect of reusable decision models in decision making and documentation.ResultsOur results show that the use of reusable decision models can significantly increase both the efficiency and the effectiveness of novice architects.ConclusionWe can report, that our findings are in line with similar studies and support the claims regarding reusable architectural design decisions in principle.     

Harmonizing architectural decisions with component view models using reusable architectural knowledge transformations and constraints

Architectural design decisions (ADDs) have been used in recent years for capturing design rationale and documenting architectural knowledge (AK). However, various architectural design views still provide the most common means for describing and communicating architectural design. The evolution of software systems requires that both ADDs and architectural design views are documented and maintained, which is a tedious and time-consuming task in the long run. Also, in lack of a systematic and automated support for bridging between ADDs and architectural design views, decisions and designs tend to become inconsistent over time. In our proposal, we introduce a reusable AK transformation language for supporting the automated transformation of reusable AK knowledge to component-and-connector models, the architectural design view used most commonly today. In addition, reusable consistency checking rules verify the consistency between decisions and designs. We evaluate our approach in an industrial case study and show that it offers high reusability, provides automation, and can, in principle, deal with large numbers of recurring decisions.     

Semi-automated architectural abstraction specifications for supporting software evolution

In this paper we present an approach for supporting the semi-automated architectural abstraction of architectural models throughout the software life-cycle. It addresses the problem that the design and implementation of a software system often drift apart as software systems evolve, leading to architectural knowledge evaporation. Our approach provides concepts and tool support for the semi-automatic abstraction of architecture component and connector views from implemented systems and keeping the abstracted architecture models up-to-date during software evolution. In particular, we propose architecture abstraction concepts that are supported through a domain-specific language (DSL). Our main focus is on providing architectural abstraction specifications in the DSL that only need to be changed, if the architecture changes, but can tolerate non-architectural changes in the underlying source code. Once the software architect has defined an architectural abstraction in the DSL, we can automatically generate architectural component views from the source code using model-driven development (MDD) techniques and check whether architectural design constraints are fulfilled by these models. Our approach supports the automatic generation of traceability links between source code elements and architectural abstractions using MDD techniques to enable software architects to easily link between components and the source code elements that realize them. It enables software architects to compare different versions of the generated architectural component view with each other. We evaluate our research results by studying the evolution of architectural abstractions in different consecutive versions of five open source systems and by analyzing the performance of our approach in these cases.     

Toward a discipline of scenario‐based architectural engineering

Software architecture analysis is a cost‐effective means of controlling risk and maintaining system quality throughout the processes of software design, development and maintenance. This paper presents a sequence of steps that maps architectural quality goals into scenarios that measure the goals, mechanisms that realize the scenarios and analytic models that measure the results. This mapping ensures that design decisions and their rationale are documented in such a fashion that they can be systematically explored, varied, and potentially traded off against each other. As systems evolve, the analytic models can be used to assess the impact of architectural changes, relative to the system's changing quality goals. Although scenarios have been extensively used in software design to understand the ways in which a system meets its operational requirements, there has been little systematic use of scenarios to support analysis, particularly analysis of a software architecture's quality attributes: modifiability, portability, extensibility, security, availability, and so forth. In this paper we present a unified approach to using scenarios to support both the design, analysis and maintenance of software architectures, and examples from large‐scale software development projects where we have applied the approach. We also present a tool, called Brie, that aids in: scenario capture, mapping scenarios to software architectures, and the association of analytic models with particular portions of architectures. The approach that we have devised, and that Brie supports, is a foundation for a discipline of architectural engineering. Architectural engineering is an iterative method of design, analysis and maintenance where design decisions are motivated by scenarios, and are supported by documented analyses.     

Bridging the gap between software architecture rationale formalisms and actual architecture documents: An ontology-driven approach

Documenting software architecture rationale is essential to reuse and evaluate architectures, and several modeling and documentation guidelines have been proposed in the literature. However, in practice creating and updating these documents rarely is a primary activity in most software projects, and rationale remains hidden in casual and semi-structured records, such as e-mails, meeting notes, wikis, and specialized documents. This paper describes the TREx (Toeska Rationale Extraction) approach to recover, represent and explore rationale information from text documents, combining: (1) pattern-based information extraction to recover rationale; (2) ontology-based representation of rationale and architectural concepts; and (3) facet-based interactive exploration of rationale. Initial results from TREx’s application suggest that some kinds of architecture rationale can be semi-automatically extracted from a project’s unstructured text documents, namely decisions, alternatives and requirements. The approach and some tools are illustrated with a case study of rationale recovery for a financial securities settlement system.     

Architectural knowledge discovery with latent semantic analysis: Constructing a reading guide for software product audits

Architectural knowledge is reflected in various artifacts of a software product. In a software product audit this architectural knowledge needs to be uncovered and its effects assessed in order to evaluate the quality of the software product. A particular problem is to find and comprehend the architectural knowledge that resides in the software product documentation. In this article, we discuss how the use of a technique called Latent Semantic Analysis can guide auditors through the documentation to the architectural knowledge they need. We validate the use of Latent Semantic Analysis for discovering architectural knowledge by comparing the resulting vector-space model with the mental model of documentation that auditors possess.     

Optimizing INTBIS on the CRAY Y-MP

INTBIS is a well-tested software package which uses an interval Newton/generalized bisection method to find all numerical solutions to nonlinear systems of equations. Since INTBIS uses interval computations, its results are guaranteed to contain all solutions. To efficiently solve very large nonlinear systems on a parallel vector computer, it is necessary to effectively utilize the architectural features of the machine In this paper, we report our implementations of INTBIS for large nonlinear systems on the Cray Y-MP supercomputer. We first present the direct implementation of INTBIS on a Cray. Then, we report our work on optimizing INTBIS on the Cray Y-MP     

Software's secret sauce: the "-ilities" [software quality]

If beauty is in the eye of the beholder, then quality must be as well. We live in a world where beauty to one is a complete turnoff to another. Software quality is no different. We have the developer's perspective, the end users perspective, the testers perspective, and so forth. As you can see, meeting the requirements might be different from being fit for a purpose, which can also be different from complying with rules and regulations on how to develop and deploy the software. Yet we can think of all three perspectives as ways to determine how to judge and assess software quality. These three perspectives tie directly to the persistent software attributes focus section in this issue and, consequently, to the concept of software "-ilities". The -ilities (or software attributes) are a collection of closely related behaviors that by themselves have little or no value to the end users but that can greatly increase a software application or system's value when added.     

Architectural styles for distributed processing systems and practical selection method

The software architecture of a system has influences against various software characteristics of the system such as efficiency, reliability, maintainability, etc. For supporting to design the software architecture, we have developed architectural styles for distributed processing systems. The styles classify the architecture for distributed processing systems into nine categories based on the location of data storage and the type of processing between a client and a server. This paper describes our architectural styles and proposes a simple but practical method to select an appropriate architectural style for developing an application system. The selection method introduces the characterization of architectural styles and the characteristic charts to visualize their characteristics of architectural styles. Next, we propose a method to select an appropriate architectural style using the conformity between characteristic charts of a system and architectural styles. We have verified the applicability of this selection method using our customers' real application systems.     

软件体系结构求精方法研究

1.引言软件设计在相当大的程度上可与建筑设计相类比,在古今中外建筑设计中,有诸多如欧洲的“歌特式”、“巴洛克式”、“维多利亚式”,中国的“园林式”、“宫廷式”等不同结构风格的建筑。同样在软件设计上,经过多年的理论探索和工程实践,也逐渐形成了一系列不同结构风格的软件体系结构。如UNIX操作系统中的管道一过滤器(pipe-filters)风格、分布式系统中典型的客户机/服务器(client/server)风格以及通信系统中的分层(layer)系统等等。     

苏北与苏南传统民居建筑的比较——立足于徐州户部山崔家大院的研究

苏北民居因其地理位置和气候特点而不同于与北方民居和南方民居,徐州地处南北交通要道,自古为北门锁钥,南国屏障,因此建筑风格承南袭北,形成自己独特的建筑风貌。文章以苏北民居的典型代表崔家大院为例与苏南传统民居进行比较,试图从比较中挖掘出隐藏在形式背后的文化涵义。在迷失中国建筑特色的今天,如何将这些传统建筑的精神融合到现代建筑设计中,则是研究中国传统建筑的意义之所在。     

Industrial Applications of Software Synthesis via Category Theory—Case Studies Using Specware

Over the last two years, we have demonstrated the feasibility of applying category-theoretic methods in specifying, synthesizing, and maintaining industrial strength software systems. We have been using a first-of-its-kind tool for this purpose, Kestrel's Specware^TM software development system. In this paper, we describe our experiences and give an industrial perspective on what is needed to make this technology have broader appeal to industry. Our overall impression is that the technology does work for industrial strength applications, but that it needs additional work to make it more usable. We believe this work marks a turning point in the use of mathematically rigorous approaches to industrial strength software development and maintenance.It is interesting to note that when this technology is applied to software systems whose outputs are designs for airplane parts, the design rationale that is captured is not only software engineering design rationale, but also design rationale from other engineering disciplines (e.g., mechanical, material, manufacturing, electrical, human factors, etc.). This suggests the technology provides an approach to general systems engineering that enables one to structure and reuse engineering knowledge broadly.     

以决策为中心的软件体系结构设计方法

提出针对体系结构层次设计的决策抽象和问题分解原则,以及基于该原则的一种以决策为中心的体系结构设计方法.该方法从决策的视角对体系结构进行建模,并通过一个从导出体系结构关键问题到对体系结构方案决策的过程完成设计,还在其中实现了候选体系结构方案的自动合成以及设计决策与理由的捕捉.这种以决策为中心的方法切合体系结构层次的特点,降低了体系结构设计的复杂性和设计决策与理由捕捉的代价.     

Inconsistency management for multiple-view software developmentenvironments

Developers need tool support to help manage the wide range of inconsistencies that occur during software development. Such tools need to provide developers with ways to define, detect, record, present, interact with, monitor and resolve complex inconsistencies between different views of software artifacts, different developers and different phases of software development. This paper describes our experience with building complex multiple-view software development tools that support diverse inconsistency management facilities. We describe software architectures that we have developed and user interface techniques that are used in our multiple-view development tools, and we discuss the effectiveness of our approaches compared to other architectural and HCI techniques     

Motivations for Open Source Project Participation and Decisions of Software Developers

We provide a rationale for open source project participation by studying the decision problems of the software programmers, whose types are different in terms of ability and intrinsic motivation. We find that motivations, both intrinsic and extrinsic, and the ability level positively affect the optimal level of effort exerted by the programmers in the open source project. In the commercial project, the programmers with higher ability exert much effort although their high level of effort is not compensated properly. Thus, the open source project might be more likely to attract capable and motivated programmers than the commercial project.