Polymorphic bytecode instrumentation

Bytecode instrumentation is a widely used technique to implement aspect weaving and dynamic analyses in virtual machines such as the Java virtual machine. Aspect weavers and other instrumentations are usually developed independently and combining them often requires significant engineering effort, if at all possible. In this article, we present polymorphic bytecode instrumentation(PBI), a simple but effective technique that allows dynamic dispatch amongst several, possibly independent instrumentations. PBI enables complete bytecode coverage, that is, any method with a bytecode representation can be instrumented. We illustrate further benefits of PBI with three case studies. First, we describe how PBI can be used to implement a comprehensive profiler of inter‐procedural and intra‐procedural control flow. Second, we provide an implementation of execution levels for AspectJ, which avoids infinite regression and unwanted interference between aspects. Third, we present a framework for adaptive dynamic analysis, where the analysis to be performed can be changed at runtime by the user. We assess the overhead introduced by PBI and provide thorough performance evaluations of PBI in all three case studies. We show that pure Java profilers like JP2 can, thanks to PBI, produce accurate execution profiles by covering all code, including the core Java libraries. We then demonstrate that PBI‐based execution levels are much faster than control flow pointcuts to avoid interference between aspects and that their efficient integration in a practical aspect language is possible. Finally, we report that PBI enables adaptive dynamic analysis tools that are more reactive to user inputs than existing tools that rely on dynamic aspect‐oriented programming with runtime weaving. These experiments position PBI as a widely applicable and practical approach for combining bytecode instrumentations. © 2015 The Authors. Software: Practice and Experience Published by John Wiley & Sons Ltd.     

A cross‐cultural study of the effect of a graph‐oriented computer‐assisted project‐based learning environment on middle school students' science knowledge and argumentation skills

The purpose of this mixed‐methods study was to explore how seventh graders in a suburban school in the United States and sixth graders in an urban school in Taiwan developed argumentation skills and science knowledge in a project‐based learning environment that incorporated a graph‐oriented, computer‐assisted application (GOCAA). A total of 42 students comprised the treatment condition and were engaged in a project‐based learning environment that incorporated a GOCAA. Of these 42 students, 21 were located in the United States and 21 were located in Taiwan. A total of 26 students comprised the control condition and were engaged in a project‐based learning environment without the GOCAA. Of these 26 students, 15 were in the United States and 11 were in Taiwan. In each country, verbal collaborative argumentation was recorded and the students' post‐essays were collected. A one‐way analysis of variance (ANOVA) was conducted for each measure of science knowledge about alternative energies. The results showed a significant treatment effect for the outcome of scientific explanation among U.S. students, while among Taiwanese students, a significant treatment effect on scientific facts was observed. A one‐way ANOVA was additionally conducted for each measure of argumentation skills and a significant treatment effect on counterarguments and rebuttals was observed among the U.S. students, while in Taiwan, a significant treatment effect on reasoning and rebuttals was observed. A qualitative analysis was conducted to examine how the GOCAA supported students' development of argumentation skills in different countries. This study found distinct argumentation patterns between the U.S. and Taiwanese intervention teams. Additionally, a distinct gender difference in the use of evidence and division of labour was noted when the Taiwanese teams were compared with the U.S. teams, which may be explained by cultural differences. This study concluded that, in both the United States and Taiwan, a project‐based learning environment incorporating a GOCAA was effective in improving students' science knowledge and developing their scientific argumentation skills.     

基于ESDA的山西省县域经济增长差异分析

采用ESDA技术,通过考察2001年~2010年山西省县域人均GDP增长率的空间分布特征及其动态变化,发现2001年~2010年山西省各地区人均GDP增长速度表现出显著的空间正相关。人均GDP增长速度聚集区的空间分布随时间的变化而变化,主要为HH类型和LL类型。     

专家系统软件开发生存期模型分析

文章根据专家系统类软件的特点,在分析已有软件开发生存期模型优缺点基础上,提出了一种适用于专家系统的开发模型,它以瀑布模型为基本框架,在不同开发阶段引入了快速原型开发模型和面向对象技术以克服瀑布模型的缺点。实践表明这种开发模型是可行的。     

OO技术在多层分布式系统中的应用

在多层分布式系统中,利用OO（Object Oriented面向对象）分析和OO设计才能开发出可以重复使用的企业对象,本文结合实例,在对象,继承,封装等概念的基础上,阐述了OO技术在分布式系统的分析、设计以及实现中的应用。     

XML的研究现状及展望

首先介绍了XML的结构、表现、特点及其建立应用的步骤,并列举了 XML的几种主要分支,然后简述了XML与其它现有相关技术的结合,给出了目前XML的主要应用领域,最后对XML的前景进行了展望。     

智能信息平台Jasmine ii研究及应用

介绍新一代Internet智能信息平台Jasmine ii的结构和特点,包括Jasmine ii的对象模型、访问技术,同时介绍了在该对象平台上开发成功的电子商务套装应用软件E－Mart Suite for Jasmine。最后,比较和分析了该软件的特点和优势。     

面向对象的统一建模语言UML及其应用

由于UML很好地实现了用户、开发人员、设计人员及管理人员之间的信息传递,提高了相互间的协作能力,使软件开发的工程化程度大大提高。基于UML对软件进行分析和建模,很好地体现了这一点。     

CT增强扫描中的小肝癌的自动检测

提出一种用模板匹配来检测CT增强扫描中的小肝癌的算法,该算法先利用改进的区域生长方法提取出完整的肝部以减少模板匹配的计算量,然后简化Y Lee等人的模板匹配方法,从而达到加快计算速度的目的。     

A hierarchical, agent-based service oriented architecture for smart environments

Service Oriented Architectures, which allow for the integration of different subsystems and of applications running on different devices and platforms, may be very suitable to solve the problem of service personalization in large smart environments like cities, where the number of potential users and potentially available services is rapidly growing. Taking this into account, we have designed an agent-based service oriented architecture for smart spaces. Two of the greatest challenges in the design of such a solution are providing effective device, service and context federation and composition mechanisms and handling user mobility. For the first challenge, we have designed a hierarchical architecture and developed a set of inheritance, aggregation and access mechanisms for devices, services and context. To handle user mobility, we have followed three different strategies, using stationary, mobile or nomadic agents. In this paper, we describe the main aspects of our architecture and perform an experimental evaluation to determine the advantages and drawbacks of the different strategies.