Does aspect-oriented modeling help improve the readability of UML state machines?

Aspect-oriented modeling (AOM) is a relatively recent and very active field of research, whose application has, however, been limited in practice. AOM is assumed to yield several potential benefits such as enhanced modularization, easier evolution, increased reusability, and improved readability of models, as well as reduced modeling effort. However, credible, solid empirical evidence of such benefits is lacking. We evaluate the “readability” of state machines when modeling crosscutting behavior using AOM and more specifically AspectSM, a recently published UML profile. This profile extends the UML state machine notation with mechanisms to define aspects using state machines. Readability is indirectly measured through defect identification and fixing rates in state machines, and the scores obtained when answering a comprehension questionnaire about the system behavior. With AspectSM, crosscutting behavior is modeled using so-called “aspect state machines”. Their readability is compared with that of system state machines directly modeling crosscutting and standard behavior together. An initial controlled experiment and a much larger replication were conducted with trained graduate students, in two different institutions and countries, to achieve the above objective. We use two baselines of comparisons—standard UML state machines without hierarchical features (flat state machines) and standard state machines with hierarchical/concurrent features (hierarchical state machines). The results showed that defect identification and fixing rates are significantly better with AspectSM than with both flat and hierarchical state machines. However, in terms of comprehension scores and inspection effort, no significant difference was observed between any of the approaches. Results of the experiments suggest that one should use, when possible, aspect state machines along with hierarchical and/or concurrent features of UML state machines to model crosscutting behaviors.     

基于扩展UML的面向方面的建模

提出了一个新的扩展UML进行面向方面建模的方法,它以合适的语义表达了AspectJ和AspectC++的元素和织入机制。在这个方法中,方面继承自类,切入点和通知继承自特征,这样切入点和通知是方面的一部分,方面与基本类的关系用横切依赖表示。切入点的图符可以表达多个方面在相同连接点的横切行为,通知以一致的方式建模结构横切和行为横切,通过在顺序图上新加一个通知发出焦点,并通知表示为消息,这样可以清晰建模通知在何时何处怎样影响系统的行为。     

基于 UML扩展的面向方面建模 *

面向方面编程 ( AOP)把横切关注点从系统中分离 ,解决了面向对象编程 ( OOP)中代码纠缠、散射的问题。但在面向方面建模中 ,横切方面没有得到很好的支持。首先 ,在统一建模语言 ( UML)元模型的基础上利用类图建立了整体框架模型 ,设计了核心类、方面、横切元素及其之间的关系 ;其次 ,利用 UML扩展机制为切点、通知、方面等主要元素建立了新的模型 ,设计了它们与方面之间新的关联关系并为其定义了语义。通过 UML扩展,使得 UML能够直接表达面向方面概念 ,支持面向方面建模设计 ,实现了面向方面模型     

基于 UML扩展的面向方面建模 *

面向方面编程（AOP）把横切关注点从系统中分离,解决了面向对象编程（OOP）中代码纠缠、散射的问题。但在面向方面建模中,横切方面没有得到很好的支持。首先,在统一建模语言（UML）元模型的基础上利用类图建立了整体框架模型,设计了核心类、方面、横切元素及其之间的关系;其次,利用UML扩展机制为切点、通知、方面等主要元素建立了新的模型,设计了它们与方面之间新的关联关系并为其定义了语义。通过UML扩展,使得UML能够直接表达面向方面概念,支持面向方面建模设计,实现了面向方面模型的可视化和可辨别性;整体框架模型使得面向方面整体结构清晰,各个核心元素之间关系明确,为面向方面建模提供了一个整体设计平台,提高了面向方面软件设计的模块化,增强了代码的重用性和系统的可维护性。     

面向方面的软件系统动态交互行为建模

面向方面编程是一种基于关注点分离的新技术,它成功地解决了面向对象编程中存在的代码缠结和散射问题。但是,在软件设计阶段,面向方面建模并没有得到很好的支持。通过分析面向方面编程的特点以及UML2．0新增的复合片段概念,本文提出了应用顺序图中的可选片段来表示Aspect与组件之间的横切交互行为,并给出将Aspect引入顺序图 的相关规定,实现了UML2．0顺序图对面向方面建模的支持。     

Aspect-Oriented Modeling and Verification with Finite State Machines

Aspect-oriented programming modularizes crosscutting concerns into aspects with the advice invoked at the specified points of program execution. Aspects can be used in a harmful way that invalidates desired properties and even destroys the conceptual integrity of programs. To assure the quality of an aspect-oriented system, rigorous analysis and design of aspects are highly desirable. In this paper, we present an approach to aspect-oriented modeling and verification with finite state machines. Our approach provides explicit notations (e.g., pointcut, advice and aspect) for capturing crosscutting concerns and incremental modification requirements with respect to class state models. For verification purposes, we compose the aspect models and class models in an aspect-oriented model through a weaving mechanism. Then we transform the woven models and the class models not affected by the aspects into FSP (Finite State Processes), which are to be checked by the LTSA (Labeled Transition System Analyzer) model checker against the desired system properties. We have applied our approach to the modeling and verification of three aspect-oriented systems. To further evaluate the effectiveness of verification, we created a large number of flawed aspect models and verified them against the system requirements. The results show that the verification has revealed all flawed models. This indicates that our approach is effective in quality assurance of aspect-oriented state models. As such, our approach can be used for model-checking state-based specification of aspect-oriented design and can uncover some system design problems before the system is implemented.     

一种基于面向侧面技术的并发式软件建模方法

基于面向侧面（Aspect-Oriented）技术及统一建模语言状态图提出了并发式软件系统开发过程中横切特性的建模方法。本方法将并发软件系统的业务逻辑和横切行为分别封装到复合状态的不同正交区域中，并通过事件广播机制反映二者的交互关系。同时，以模块化的状态迁移系统 （Modular Transition System）作为基本计算模型，对该建模方法进行形式化描述，给出了模型元素及建模过程的精确语义。实例研究表明，该方法在并发软件设计阶段实现了横切关注点的分离策略，并使得系统模型具有松耦合、适应性和可跟踪性的优点。     

基于UML的面向方面建模方法

面向方面编程（AOP）技术通过横切关注来实现软件系统.面向方面建模可通过扩展UML来实现,在元模型层次上设计面向方面软件开发（AOSD）模型框架.从结构建模、行为建模、方面织入以及代码产生几个方面实现面向方面的建模方法.利用UML类图实现方面的结构模型,方面与核心组件及方面之间的静态模型关系.协作图表达方面与核心组件及方面之间的动态行为,并通过状态图细化方面和核心组件的动态行为,实现状态图的方面与核心组件及方面之间的织入关系,最终实现方面代码的自动生成.基于UML的方面建模填补AOP与OOP技术之间的空白,提高软件设计的模块化,增强代码的重用性、维护性.     

Aspect-oriented modeling framework for security hardening

Aspect-oriented modeling (AOM) emerged as a promising paradigm for handling crosscutting concerns, such as security, at the software modeling level. Most existing AOM contributions are presented from a practical perspective and lack formal syntax and semantics. In this paper, we present a practical and formal AOM framework for software security hardening. Our contributions are threefold. First, we define an AOM approach for the specification of security aspects at the unified modeling language (UML) design level. Second, we design and implement the matching and the weaving processes into UML design models. Third, we elaborate formal specifications for aspect matching and weaving in UML activity diagrams. Finally, we demonstrate the viability and the relevance of our propositions using a case study. The proposed framework is supported by a tool built on top of IBM-Rational Software Modeler.     

基于UML面向方面需求建模

面向方面编程(AOP)提供模块化横切关注点的机制,有效地解决横切属性引起的代码混乱和代码分散等问题.但是,AOP目前大都用在程序级和执行级,在软件开发的早期阶段中运用较少.在需求分析阶段分离功能关注点和非功能关注点,运用UML类图、状态图对方面进行建模,并实现非功能关注点的编织,完成系统建模的整个过程,并在此基础上给出了方面间的检测和解决方法.     

Synthesizing Distributed Protocol Specifications from a UML State Machine Modeled Service Specification

The object-oriented paradigm is widely applied in designing and implementing communication systems.Unified Modeling Language(UML) is a standard language used to model the design of object-oriented systems.A protocol state machine is a UML adopted diagram that is widely used in designing communication protocols.It has two key attractive advantages over traditional finite state machines:modeling concurrency and modeling nested hierarchical states.In a distributed communication system,each entity of the system has its own protocol that defines when and how the entity exchanges messages with other communicating entities in the system.The order of the exchanged messages must conform to the overall service specifications of the system.In object-oriented systems,both the service and the protocol specifications are modeled in UML protocol state machines.Protocol specification synthesis methods have to be applied to automatically derive the protocol specification from the service specification.Otherwise,a time-consuming process of design,analysis,and error detection and correction has to be applied iteratively until the design of the protocol becomes error-free and consistent with the service specification.Several synthesis methods are proposed in the literature for models other than UML protocol state machines,and therefore,because of the unique features of the protocol state machines,these methods are inapplicable to services modeled in UML protocol state machines.In this paper,we propose a synthesis method that automatically synthesizes the protocol specification of distributed protocol entities from the service specification,given that both types of specifications are modeled in UML protocol state machines.Our method is based on the latest UML version(UML2.3),and it is proven to synthesize protocol specifications that are syntactically and semantically correct.As an example application,the synthesis method is used to derive the protocol specification of the H.323 standard used in Internet calls.     

ATM系统的面向方面模型

基于UML的ATM系统面向方面模型,能够把关注从系统中分离出来,形成一个独立于系统的方面模块。面向方面编程(AOP)技术允许把设计好的方面模块根据特定需要重新织入系统,组合为完整系统。模型扩展了UML来表达方面元素概念,并从系统的静态结构模型和方面织入建模ATM系统。     

Synthesizing object life cycles from business process models

Unified modeling language (UML) activity diagrams can model the flow of stateful business objects among activities, implicitly specifying the life cycles of those objects. The actual object life cycles are typically expressed in UML state machines. The implicit life cycles in UML activity diagrams need to be discovered in order to derive the actual object life cycles or to check the consistency with an existing life cycle. This paper presents an automated approach for synthesizing a UML state machine modeling the life cycle of an object that occurs in different states in a UML activity diagram. The generated state machines can contain parallelism, loops, and cross-synchronization. The approach makes life cycles that have been modeled implicitly in activity diagrams explicit. The synthesis approach has been implemented using a graph transformation tool and has been applied in several case studies.     

一种基于CSP的面向方面状态图形式化描述方法

面向方面通过分离关注点解决软件系统中的横切问题,通过扩展UML可实现对面向方面的建模。本文利用UML的扩展机制将方面加入状态图中,描述了状态图中的方面与核心组件以及方面之间的编织,然后利用进程代数的形式化语义描述了扩展后的UML状态图,克服了扩展UML描述状态图的缺乏形式化动态语义,不利于对模型进行形式化验证和证明的缺
点。最后,以ATM自动取款机为例验证了基于CSP的面向方面状态图形式化描述的有效性。     

OPM vs. UML--Experimenting with Comprehension and Construction of Web Application Models

Object-Process Methodology (OPM), which is a holistic approach to modeling and evolving systems, views objects and processes as two equally important entities that describe the system's structure and behavior in a single model. Unified Modeling Language (UML), which is the standard object-oriented modeling language for software systems, separates the system model into various aspects, each of which is represented in a different view (diagram type).The exponential growth of the Web and the progress of Internet-based architectures have set the stage for the proliferation of a variety of Web applications, which are classified as hybrids between hypermedia and information systems. Such applications require a modeling approach that is capable of clearly specifying aspects of their architecture, communication, and distributive nature. Since UML and OPM are two candidates for this task, this study has been designed to establish the level of comprehension and the quality of the constructed Web application models using each one of these two approaches.In the experiment we carried out, third year undergraduate information systems engineering students were asked to respond to comprehension and construction questions about two representative Web application models. The comprehension questions related to the system's structure, dynamics, and distribution aspects. The results suggest that OPM is better than UML in modeling the dynamics aspect of the Web applications. In specifying structure and distribution aspects, there were no significant differences. The results further suggest that the quality of the OPM models students built in the construction part was superior to that of the corresponding UML models.     

Using UML Action Semantics for model execution and transformation

The Unified Modelling Language (UML) lacks precise and formal foundations and semantics for several modeling constructs, such as transition guards or method bodies. These semantic discrepancies and loopholes prevent executability, making early testing and validation out of reach of UML tools. Furthermore, the semantic gap from high-level UML concepts to low-level programming constructs found in traditional object-oriented language prevents the development of efficient code generators.The recent Action Semantics (AS) proposal tackles these problems by extending the UML with yet another formalism for describing behavior, but with a strong emphasis on dynamic semantics. This formalism provides both, a metamodel integrated into the UML metamodel, and a model of execution for these statements. As a future OMG standard, the AS eases the move to tool interoperability, and allows for executable modeling and simulation.We explore in this paper a specificity of the AS: its applicability to the UML metamodel, itself a UML model. We show how this approach paves the way for powerful metaprogramming for model transformation. Furthermore, the overhead for designers is minimal, as mappings from usual object-oriented languages to the AS will be standardized.     

实时系统的面向方面模型

基于UML的实时系统面向方面模型,能够把实时关注从系统中分离出来,形成一个独立于系统的时间方面,实现时间方面的并发设计和系统时间特性的统一管理。面向方面编程（AOP）技术允许把设计好的时间方面根据特定需要重新织入系统,组合为实时系统。模型扩展了UML来表达AOP技术和时间概念,并从系统的静态结构模型、动态行为模型和时间方面的织入等几部分建模实时系统。一个电梯控制系统例子充分说明这种设计过程。     

一种面向方面的UML建模方法研究

针对面向对象编程(OOP)中横切关注点与业务逻辑代码纠缠的现象,提出了一种面向方面编程(AOP)的统一建模方法以弥补OOP的不足;该基于UML的方面建模方法从AOP与OOP技术存在的问题出发,通过基于UML的AOP建模方法研究,提高了软件设计的模块化,增强了代码的重用性、维护性;最后,以银行系统ATM中的取款业务的建模为例来描述用UML建模过程,为AOP建模提供了一种新的研究思路。     

基于AOP的时空Petri网的CPS建模

信息-物理融合系统(Cyber-Physical System,CPS)作为一系列物理过程和计算过程的紧密集成,体现为物理世界和信息世界的交互与融合。针对CPS的时空及非功能属性,提出一种面向方面的时空Petri网建模方法,在保证时空一致性的前提下,分离系统中的核心关注点和横切关注点,将横切关注点单独作为方面进行分析,并将构建规则方面重新织入系统。该方法在系统设计阶段可以对不同的非功能属性进行形式化分析,提高了系统的可靠性和可维护性。最后通过实例说明了该方法的可行性。     

Confluence of aspects for sequence diagrams

The last decade has seen several aspect language proposals for UML 2 sequence diagrams. Aspects allow the modeler to define crosscutting concerns of sequence diagrams and to have these woven with the sequence diagrams of a so-called base model, in order to create a woven model. In a real-world scenario, there may be multiple aspects applicable to the same base model. This raises the need to analyse the set of aspects to identify possible aspect interactions (dependencies and conflicts) between applications of aspects. We call a set of aspects terminating if they may not be applied infinitely many times for any given base model. Furthermore, we call a set of terminating aspects confluent, if they, for any given base model, always yield the same final result regardless of the order in which they are applied. Since confluence must hold for any base model, this is a much stronger result than many of the current approaches that have addressed detection of aspect interactions limited to a specific base model. Our aspects are specified using standard sequence diagrams with some extensions. In this paper, we present a confluence theory specialized for our highly expressive aspect language. For the most expressive aspects, we prove that confluence is undecidable. For another class of aspects with considerable expressiveness, we prescribe an algorithm to check confluence. This algorithm is based on what we call an extended critical pair analysis. These results are useful both for modelers and researchers working with sequence diagram aspects and for researchers wanting to establish a confluence theory for other aspect-oriented modelling or model transformation approaches.