Systematic pattern selection using pattern language grammars and design space analysis

Software patterns provide reusable solutions to recurring design problems in a particular context. The software architect or designer must find the relevant patterns and pattern languages that need to be considered, and select the appropriate patterns, as well as the best order to apply them. If the patterns and pattern languages are written by multiple pattern authors, it might be necessary to identify interdependencies and overlaps between these patterns and pattern languages first. Out of the possible multitude of patterns and pattern combinations that might provide a solution to a particular design problem, one fitting solution must be selected. This can only be mastered with a sufficient expertise for both the relevant patterns and the domain in which they are applied. To remedy these issues we provide an approach to support the selection of patterns based on desired quality attributes and systematic design decisions based on patterns. We propose to formalize the pattern relationships in a pattern language grammar and to annotate the grammar with effects on quality goals. In a second step, complex design decisions are analyzed further using the design spaces covered by a set of related software patterns. This approach helps to systematically find and categorize the appropriate software patterns—possibly even from different sources. As a case study of our approach, we analyze patterns from a pattern language for distributed object middleware. Copyright © 2006 John Wiley & Sons, Ltd.     

A quantitative approach for evaluating the quality of design patterns

In recent years, the influence of design patterns on software quality has attracted an increasing attention in the area of software engineering, as design patterns encapsulate valuable knowledge to resolve design problems, and more importantly to improve design quality. As the paradigm continues to increase in popularity, a systematic and objective approach to verify the design of a pattern is increasingly important. The intent session in a design pattern indicates the problem the design pattern wants to resolve, and the solution session describes the structural model for the problem. When the problem in the intent is a quality problem, the structure model should provide a solution to improve the relevant quality. In this work we provide an approach, based on object-oriented quality model, to validate if a design pattern is well-designed, i.e., it answers the question of the proposed structural model really resolves the quality problems described in the intent. We propose a validation approach to help pattern developers check if a design pattern is well-designed. In addition, a quantitative method is proposed to measure the effectiveness of the quality improvement of a design pattern that pattern users can determine which design patterns are applicable to meet their functional and quality requirements.     

An expert system for the selection of software design patterns

Abstract: This paper describes the development of a prototype expert system for the selection of design patterns that are used in object-oriented software. Design patterns provide one method of software reuse, which supports the goal of improved software development productivity. The prototype system represents an initial step towards providing an automated solution regarding the design pattern application problem, i.e. leading a designer to a suitable design pattern which is applicable to the problem at hand. The feasibility of using expert system technology to aid in the selection problem is demonstrated.     

Software design patterns classification and selection using text categorization approach

ContextNumerous software design patterns have been introduced and cataloged either as a canonical or a variant solution to solve a design problem. The existing automatic techniques for design pattern(s) selection aid novice software developers to select the more appropriate design pattern(s) from the list of applicable patterns to solve a design problem in the designing phase of software development life cycle.GoalHowever, the existing automatic techniques are limited to the semi-formal specification, multi-class problem, an adequate sample size to make precise learning and individual classifier training in order to determine a candidate design pattern class and suggest more appropriate pattern(s).MethodTo address these issues, we exploit a text categorization based approach via Fuzzy c-means (unsupervised learning technique) that targets to present a systematic way to group the similar design patterns and suggest the appropriate design pattern(s) to developers related to the specification of a given design problem. We also propose an evaluation model to assess the effectiveness of the proposed approach in the context of several real design problems and design pattern collections. Subsequently, we also propose a new feature selection method Ensemble-IG to overcome the multi-class problem and improve the classification performance of the proposed approach.ResultsThe promising experimental results suggest the applicability of the proposed approach in the domain of classification and selection of appropriate design patterns. Subsequently, we also observed the significant improvement in learning precision of the proposed approach through Ensemble-IG.ConclusionThe proposed approach has four advantages as compared to previous work. First, the semi-formal specification of design patterns is not required as a prerequisite; second, the ground reality of class label assignment is not mandatory; third, lack of classifier’s training for each design pattern class and fourth, an adequate sample size is not required to make precise learning.     

设计模式在网管系统中的应用

设计模式是指在软件设计过程中反复出现的一些问题的解决方法,文章详细论述了单件模式、观察者模式、命令模式、装饰模式、工厂模式在一个网管系统中的设计应用,并详细分析了如果不使用模式设计会给系统带来的问题。     

The Potemkin village and the art of deception

Potemkin village is "something that appears elaborate and impressive but in actual fact lacks substance". The software analogies for the Potemkin village are ripe for exploration. Software antipatterns address problem-solution pairs in which the typical solution is more harmful than the problem it solves. In essence, an antipattern presents an identifiable problem, the accompanying harmful effects of the typical solution, and a more appropriate solution called a refactoring. In this sense, the software version of a Potemkin village is an antipattern: Problem: deliver software with an impressive interface quickly. Solution: employ a ready-made architecture that provides an impressive interface quickly; spend as little time as possible on the back-end processing. Refactoring: do it right the first time. The author doesn't want to make the case too strongly that the building of Potemkin villages is a deliberate strategy of fraud that companies perpetrate. Is a weak piece of software covered by an elaborate GUI a deliberate fraud or simply poor design? You must assume the latter in the absence of proof. When faced with a Potemkin village or an emperor's new clothes situation, you must expose it immediately. Doing so is not easy when a high-quality GUI masks the shortcomings. You can, however, detect the situation through design reviews, and code inspections, reviews, or walkthroughs. Therefore, managers who oversee software projects (and customers who buy software) should require these reviews. Testing can sometimes uncover the situation, but it might be too late at this point. Test-driven design, on the other hand, can help avoid a Potemkin village.     

An exploratory study on cooccurrence of design patterns and bad smells using software metrics

A design pattern is a general reusable solution to commonly recurring problems in software projects. Bad smells are symptoms existing in the source code that possibly indicate the presence of a structural problem that requires code refactoring. Although design pattern and bad smells be different concepts, literature has shown that they may be related and cooccur during the evolution of a software system. This paper presents an empirical study that investigates cooccurrences of design patterns and bad smells as well as identifies the main factors that contribute to the emergence of the relationship between them. We carried out a case study with five Java systems to: (1) investigate if the use of design pattern reduces bad smell occurrence, (2) identify cooccurrences of design patterns and bad smells, and (3) identify situations that contribute for the cooccurrence emergence. As the main result, we found that the application of design pattern not necessarily avoid bad smell occurrences. The results also show that some design patterns such as composite, factory method, and singleton, are intrinsically modular and might be useful in creating high-quality systems. However, other design patterns such as adapter-command, proxy, and state-strategy, have presented high cooccurrence frequency with bad smells; therefore, they require attention in their implementation. Finally, via manual inspection in the components with cooccurrence, we found that the identified cooccurrences appeared due to poor planning and inadequate application of design patterns.     

基于设计模式的管网GIS

设计模式是近年来软件工程领域中的热门研究课题,它有效地解决了软件设计策略的复用问题。文章探讨了适合GIS领域的设计模式,并基于设计模式进行了管网GIS的设计,最后举出了一个武汉排水管理信息系统的实例。     

SDH网管软件开发中的设计模式

设计模式描述了在软件开发过程中经常出现的问题及其解决方案,是软件复用的有效途径。文章详细地分析了设计摸式中的Factory模式、Observer模式、Bridge模式在SDH网管软件开发中的应用,证明了在SDH网管系统中运用设计模式能够有效地提高系统质量、优化系统结构。     

A controlled experiment in maintenance: comparing design patternsto simpler solutions

Software design patterns package proven solutions to recurring design problems in a form that simplifies reuse. We are seeking empirical evidence whether using design patterns is beneficial. In particular, one may prefer using a design pattern even if the actual design problem is simpler than that solved by the pattern, i.e., if not all of the functionality offered by the pattern is actually required. Our experiment investigates software maintenance scenarios that employ various design patterns and compares designs with patterns to simpler alternatives. The subjects were professional software engineers. In most of our nine maintenance tasks, we found positive effects from using a design pattern: either its inherent additional flexibility was achieved without requiring more maintenance time or maintenance time was reduced compared to the simpler alternative. In a few cases, we found negative effects: the alternative solution was less error-prone or required less maintenance time. Overall, we conclude that, unless there is a clear reason to prefer the simpler solution, it is probably wise to choose the flexibility provided by the design pattern because unexpected new requirements often appear. We identify several questions for future empirical research     

Pattern-based design evolution using graph transformation

In recent years, design patterns gain more interest in software engineering communities for both software development and maintenance. As a template to solve a certain recurring problem, a design pattern documents successful experiences of software experts and gradually becomes the design guidelines of software development. Applying design patterns correctly can improve the efficiency of software design in terms of reusability and enhance maintainability during reverse engineering. Software can be evolved when developers modify their initial designs as requirements change. For instance, a developer may add/delete a set of design elements, such as classes and methods. Modifications on software artifacts can introduce conflicts and inconsistencies in the previously applied design patterns, which are difficult to find and time-consuming to correct. This paper presents a graph-transformation approach to pattern level design validation and evolution. Based on a well founded formalism, we validate a given design by a graph grammar parser and automatically evolve the design at pattern level using a graph-transformation system. Rules for potential pattern evolutions are predefined. The graph-transformation approach preserves the integrity and consistency of design patterns in the system when designs change. A prototype system is built and a case study on the Strategy pattern demonstrates the feasibility of pattern-based design validation and evolution using graph transformation techniques.     

角色模型在软件建模中的应用

本文针对模式应用中出现的由于软件模式是解决问题的详细设计而无法实现从分析到设计的平滑转换的问题，提出在分析阶段便使用软件模式，引入了Role模式并把它作为从分析阶段至类图设计阶段的中介，阐述了如何从Use case中抽取Role模式，如何从Ro1e模式转换至Class类图，最终得到Class详细设计图，以帮助软件开发者有效利用软件模式，顺利实现从分析过程至设计过程的过渡。     

Patterns for design in microtechnology

Miniaturization is a trend in mechanical engineering, in which 3D mechanical structures are required. Consequences are changed production and design processes. Furthermore micro-specific design requires in-depth knowledge of production technology. One successful means for ensuring the consideration of these restrictions are design rules. However, many aspects of design relevant knowledge are not restrictive and cannot be represented by design rules. The authors propose the application of design patterns, which represent problem- and solution-oriented knowledge. A pattern describes the abstract solution for a frequently occurring problem in a specific context. This approach was first introduced to architecture and then adapted to software engineering. Also first moves were made to use pattern languages in engineering design. The authors propose design patterns to represent design knowledge for microsystem technologies. As methodological means of support, a pattern lifecycle activity model and subordinate methods are presented.     

Design patterns selection: An automatic two-phase method

Over many years of research and practices in software development, hundreds of software design patterns have been invented and published. Now, a question which naturally arises is how software developers select the right design patterns from all relevant patterns to solve design problems in the software design phase. To address this issue, in this paper, we propose a two-phase method to select a right design pattern. The proposed method is based on a text classification approach that aims to show an appropriate way to suggest the right design pattern(s) to developers for solving each given design problem. There are two advantages of the proposed method in comparison to previous works. First, there is no need for semi-formal specifications of design patterns and second, the suitable design patterns are suggested with their degree of similarity to the design problem. To evaluate the proposed method, we apply it on real problems and several case studies. The experimental results show that the proposed method is promising and effective.     

Mining Design Pattern Use Scenarios and Related Design Pattern Pairs: A Case Study on Online Posts

In common design pattern collections, e.g., design pattern books, design patterns are documented with templates that consist of multiple attributes, such as intent, structure, and sample code. To adapt to modern developers, the depictions of design patterns, especially some specific attributes, should advance with the current programming technologies, for example, “known uses”, which exemplifies the use scenarios of design patterns in practice, and “related patterns”, which describes the relatedness between a design pattern and the others within a context. However, it is not easy to update the contents of these attributes manually due to the diversity of the programming technologies. To address this problem, in this work, we conducted a case study to mine design pattern use scenarios and related design pattern pairs from Stack Overflow posts to enrich the two attributes. We first extracted the question posts relevant to each design pattern by identifying the design pattern tags. Then, the topics of the posts were discovered by applying topic modeling techniques. Finally, by analyzing the topics specified for each design pattern, we detected 195 design pattern use scenarios and 70 related design pattern pairs, involving 61 design patterns totally. These findings are associated with a variety of popular software frameworks and programming techniques. They could complement the existing design pattern collections and help developers better acknowledge the usage and relatedness of design patterns in today’s programming practice.

     

面向Java语言的设计模式抽取方法的研究

从源码中抽取设计模式对于提高软件可理解性和可维护性、软件设计重用以及软件重构具有重要意义。文章面向Java语言提出了一个从源码中抽取设计模式的方法。具体地,研究了一种特定的设计模式描述方法、定义了源码信息模型及其化简方法,以此为基础提出了设计模式模型和源码模型的匹配方法。特别讨论了在抽取设计模式时与container类相关的问题及其解决方案。最后根据抽取结果从模式及其实例的角度对方法进行了评价,并提出了必要的优化技术。     

一个更容易应用软件模式的方法

当前的软件模式都是解决某个特定问题的详细设计方案，一般都用类结构图来表示，无法实现从分析到设计的平滑过渡，从而导致了在模式的应用中对模式的生搬硬套，达不到应有的效果。该文使用了Role、Meta-pattern等技术，获得了一个更加容易的使用方法.     

JAVA类库中的策略模式

为了使程序具有一个良好、灵活的结构，充分的可扩展性和代码的可重用性，设计模式在面向对象程序设计中的应用具有重要的意义和作用。本文以策略模式在JAVA类库中的应用为例，具体介绍策略模式问题的产生、解决和效果。最后以实例说明运用此设计模式带来软件扩充和复用的方便性。     

基于角色的设计模式建模和实现方法

虽然设计模式有利于软件的重用,但当设计模式实例化时,存在模式的重叠、可追踪性以及模式代码难于重用等问题.提出一种基于角色的设计模式的建模和实现方法,在设计和实现两个层面上解决上述问题.该方法把设计模式的角色作为独立的建模元素,在应用程序类和角色间导入RoleOf关系,使应用逻辑和模式逻辑完全分离,从而提高其重用性.使用UML的标准扩充机制,给出了RoleOf关系的元模型和语义,以及标识模式信息的构造型和标记值,以此解决模式的重叠和可追溯性等问题.通过对Java语言进行扩充(称为Rava),实现了应用逻辑和模式逻辑的动态绑定.该方法较好地解决了设计模式实例化时的模式重叠和可追踪性问题,提高了模式逻辑的可重用性,对运用设计模式开发软件有一定的指导作用.