Bigraph理论在自适应软件体系结构上的应用

现有的软件体系结构形式化方法对体系结构的动态性、自适应性支持有限,并不能很好地验证系统演化过程中的一致性、完整性等动态特征.Bigraph理论融合了,π演算和移动Ambient演算的优势,重点强调计算的位置和连接两方面因素,具有较为完整、可扩展的理论框架.这使得Bigraph不仅在概念上能够满足现有自适应软件对结构和行为的需求,而且还提供了直观、普适的表达能力.文中简要介绍了Bigraph的基本概念和现状,利用Bigraph理论对自适应软件体系结构进行了形式化规约,分析和验证了系统动态演化的性质,并探讨了Bigraph理论在自适应软件体系结构形式化方面的优势和拓展方向.     

基于Bigraph的面向方面动态软件体系结构演化研究

随着网络技术的发展,软件运行环境的开放化和用户需求的多样化,使得人们对软件动态演化能力提出了更高的要求.面向方面软件开发中的关注点分离思想很好地支持了软件动态演化,现有的形式化方法难以直观地表示体系结构的动态性,且不能很好地验证系统演化前后的正确性.Bigraph不仅具有直观的图形化表达能力,而且具备良好的数学基础,可以推理和验证系统的演化性质.因此,提出了一种面向方面动态软件体系结构(AODSA)模型,扩展的Bigraph用于描述AODSA的结构,使用Bigraph反应系统(BRS)来描述AODSA的动态演化.最后以一个简化的ATM存款系统模型为例,说明Bigraph表示的ATM模型以及基于BRS的演化过程.     

一种基于Bigraph理论的软件演化过程模型研究

基于Bigraph理论对软件演化过程模型进行研究, 目的是能更好地对软件演化过程中相关动态变化进行建模。利用Bigraph理论和软件演化过程的思想, 首先提出了一个形式化的软件演化过程模型, 然后用扩展的Bigraph来描述软件演化过程模型的结构, 使用Bigraph反应系统来描述软件演化过程模型的动态变化, 最后对软件演化过程模型动态调整后的完整性进行了验证。     

构件系统建模及其动态演化一致性验证方法

基于构件的软件开发已成为软件开发的主流方法,但针对构件系统动态演化后的一致性保持问题,目前尚缺乏统一的标准,为此提出一种验证构件系统动态演化一致性的方法。首先,应用进程代数构造构件模型,并在此基础上得到粗粒度的构件系统模型;然后,根据构件系统模型及其状态的变化,提出构件系统外部行为提取算法,并基于弱互模拟理论定义构件系统动态演化一致性的验证准则;最后,提取演化前后构件系统的行为,并将其转换成便于Pi演算自动工具MWB(Mobility Workbench)识别的格式,以进行行为一致性验证。案例研究表明,该方法是可行且有效的。     

一种支持动态演化的AOP框架

传统面向对象(OOP)框架对软件的变化性和复杂性支持有限.为此,基于C++语言,提出一种支持动态演化的面向方面编程框架——AODF.给出Bigraph理论的静态和动态建模过程,通过Bigraph反应系统实现AODF的动态演化,使用图形及形式化的项语言表述其演化过程.实验结果表明,与传统OOP框架相比,AODF的代码模块化程度更高,软件系统扩展性更好.     

移动IPv6的快速切换的代数验证

利用π演算理论分析移动通信系统,可以严格而规范地描述其协议过程,并给予代数验证。文章基于π演算理论来分析移动IPv6的快速切换机制。首先建立了切换的π演算模型,然后通过推导,证明了模型的一致性。这将为移动IPv6的快速切换的研究提供一定的参考和分析价值。     

基于高阶π演算的构件演化行为研究

用形式化的方法分析软件演化过程中构件的行为已成为目前构件开发中的研究热点。为了满足构件演化过程中行为建模形式化的需要,建立了一种基于高阶π演算的构件演化行为分析方法。对构件演化行为进行分类,将顺序图表示的演化请求转换成高阶π演算进程表达式,通过高阶π演算的语法语义和等价理论等数学基础对演化行为进行推演,并检测演化中是否存在死锁问题。最后通过实例对该方法进行分析说明,从而验证了该方法的可行性和有效性。     

面向软件动态演化的需求建模及其模型规范化

针对目前需求工程阶段对软件动态演化考虑不足的现状,在分析软件动态演化面临的挑战的基础上,设计了面向动态演化的需求元模型(dynamic-evolution-orientedrequi rements meta-model,DERM)。该元模型以特征为基本部件,按特征组合的方式建立需求模型,需求模型由行为特征和属性特征组成。行为特征被区分为计算行为特征和交互行为特征,以实现计算和交互的相对隔离;属性特征通过其作用域,指定其在行为特征模型中的作用范围,从而将行为特征模型和属性特征模型统一为需求模型。在此基础上,讨论了需求模型的参照完整性、依赖一致性和互斥一致性,并进一步把需求模型规范化为需求模型第一范式到第三范式,需求模型规范化的过程提供了一种保证需求模型一致性的方法。最后通过案例研究,表明了该方法的可行性及其对软件动态演化的有效支持。     

基于构件动态演化的行为一致性验证方法

为了保证构件在动态演化中的行为一致性,避免不合法的构件演化,提出一种基于进程代数的构件模型,引入对外主动请求接口和内部连接,形式化描述构件及其对外交互协议,给出相关定理和验证算法。实例证明,该构件模型可以验证动态演化中的接口兼容性、外部交互行为一致性,以及运行时行为完整性。     

构件动态演化内部一致性保证方法

基于构件的软件开发已成为软件开发的主流方法,针对构件式软件动态演化后的一致性保持问题,目前大多数学者主要是从构件式软件的外部一致性角度进行分析和研究。为此,从构件内部的角度出发,提出一种保证构件式软件动态演化构件内部一致性的方法。首先,对构件及其相关模型进行建模,并给出了构件内部类有向图的同态映射关系的判定算法;其次,给出构件式构件动态演化内部一致性的标准,基于进程代数的强模拟理论和图论中的同态映射关系,分别从全局和局部的角度定义了构件式软件动态演化前后构件内部一致性标准的充分条件和必要条件,并对其进行了证明;然后,基于上述工作,给出了构件动态演化内部一致性保证方法的流程;最后,通过案例研究表明该方法的可行性和有效性。     

新的二部图判定算法

二部图是现代图论中一类非常重要的图,然而关于其判定的充要条件却很少,而且用算法实现它们很复杂.需要指数级的时间代价.利用图的广度优先遍历,提出了一个易于实现的二部图判定的充要条件:无向图G是二部图当且仅当G的广度优先生成森林中的同一层上的任意两点在G中不邻接.给出了该判定条件的实现算法,算法的时间复杂度是O(n2),很好地解决了二部图的判定问题.     

动态增量式AOP框架的研究与实现

在研究AOP原理的基础上,提出一种面向aspect的编程框架AODF,采用基于日志技术的增量式编织机制,不仅提高了编织效率,而且基于Bigraph理论的AODF支持方面的动态演化,实现了行为的一致性与相容性。另外,AODF从语言层提供对方面的支持,无需改动语言本身任何结构及特性,而且可以把自行编制的aspect配置为标准组件入库,实现方面的重用。从而使得遗留系统无需变更就可以获得面向方面的扩展。     

Migration of existing software systems to mobile computing platforms: a systematic mapping study

Mobile computing has fast emerged as a pervasive technology to replace the old computing paradigms with portable computation and context-aware communication. Existing software systems can be migrated (while preserving their data and logic) to mobile computing platforms that support portability, context-sensitivity, and enhanced usability. In recent years, some research and development efforts have focused on a systematic migration of existing software systems to mobile computing platforms.To investigate the research state-of-the-art on the migration of existing software systems to mobile computing platforms. We aim to analyze the progression and impacts of existing research, highlight challenges and solutions that reflect dimensions of emerging and futuristic research.We followed evidence-based software engineering (EBSE) method to conduct a systematic mapping study (SMS) of the existing research that has progressed over more than a decade (25 studies published from 1996–2017).We have derived a taxonomical classification and a holistic mapping of the existing research to investigate its progress, impacts, and potential areas of futuristic research and development.The SMS has identified three types of migration namely Static, Dynamic, and State-based Migration of existing software systems to mobile computing platforms.Migration to mobile computing platforms enables existing software systems to achieve portability, context-sensitivity, and high connectivity. However, mobile systems may face some challenges such as resource poverty, data security, and privacy. The emerging and futuristic research aims to support patterns and tool support to automate the migration process. The results of this SMS can benefit researchers and practitioners–by highlighting challenges, solutions, and tools, etc., –to conceptualize the state-ofthe- art and futuristic trends that support migration of existing software to mobile computing.     

Multi-tenant Verification-as-a-Service (VaaS) in a cloud

Formal methods and verification technique are often used to develop mission-critical systems. Cloud computing offers new computation models for applications and the new model can be used for formal verification. But formal verification tools and techniques may need to be updated to exploit the cloud architectures. Multi-Tenant Architecture (MTA) is a design architecture used in SaaS (Software-as-a-Service) where a tenant can customize its applications by integrating either services already stored in the SaaS database or newly supplied services. This paper proposes a new concept VaaS (Verification-as-a-Service), similar to SaaS, by leveraging the computing power offered by a cloud environment with automated provisioning, scalability, and service composition. A VaaS hosts verification software in a cloud environment, and these services can be called on demand, and can be composed to verify a software model. This paper presents a VaaS architecture with components, and ways that a VaaS can be used to verify models. Bigragh is selected as the modeling language for illustration as it can model mobile applications. A Bigraph models can be verified by first converting it to a state model, and the state model can be verified by model-checking tools. The VaaS services combination model and execution model are also presented. The algorithm of distributing VaaS services to a cloud is given and its efficiency is evaluated. A case study is used to demonstrate the feasibility of a VaaS.     

Evolutionary robotics: the Sussex approach

We give an overview of evolutionary robotics research at Sussex over the last five years. We explain and justify our distinctive approaches to (artificial) evolution, and to the nature of robot control systems that are evolved. Results are presented from research with evolved controllers for autonomous mobile robots, simulated robots, co-evolved animats, real robots with software controllers, and a real robot with a controller directly evolved in hardware.     

偶图及其应用研究综述

偶图是由Robin Milner在2001年提出的一种基于图形的形式化理论模型,试图为普适计算提供一个设计、模拟和分析的平台以及为现有的进程代数提供一个统一的可扩展的框架.介绍了偶图的基本概念,揭示了偶图的数学基础——预范畴、范畴、s-范畴、对称偏幺半范畴之间的关系,对偶图的代数系统进行总结,简化了偶图的离散范式的表述形式,并给予证明.综述了偶图的发展及其应用概况.对偶图范畴的定义、商变换等基本理论中存在的一些问题提出讨论,指出偶图范畴应该属于小范畴而不是大范畴,并给出商变换得出的大范畴转换为小范畴的方法.最后简述了偶图模型的扩展、应用的拓广.     

Determinants of behavioral intention to mobile banking

With the improvement of mobile technologies and devices, banking users are able to conduct banking services at anyplace and at anytime. Recently, many banks in the world have provided mobile access to financial information. The reason to understand what factors contribute to users’ intention to use mobile banking is important issue of research. The purpose of this research is to examine and validate determinants of users’ intention to mobile banking. This research used a structural equation modeling (SEM) to test the causalities in the proposed model.The results indicated strong support for the validity of proposed model with 72.2% of the variance in behavioral intention to mobile banking. This study found that self-efficiency was the strongest antecedent of perceived ease-of-use, which directly and indirectly affected behavioral intention through perceived usefulness in mobile banking. Structural assurances are the strongest antecedent of trust, which could increase behavioral intention of mobile banking. This research verified the effect of perceived usefulness, trust and perceived ease-of-use on behavioral intention in mobile banking. The results have several implications for mobile banking managers.