面向多租户Web应用的性能隔离方法

提出一种面向应用级共享的多租户Web应用性能隔离方法.首先建立基于事务处理链的应用级资源管理模型,基于信号量机制给出了模型的并发控制算法,支持事务级、分阶段的多租户Web应用资源管理,并在一次事务处理的各阶段实现线程复用,避免因修改交互协议而产生的再工程代价.基于上述工作,给出多租户性能隔离算法及策略,并利用TPC-W电子商务应用验证方法的系统开销及有效性.实验结果表明,该方法可以有效降低租户资源侵占行为的影响,并避免系统过载.     

Cross-company vs. single-company web effort models using the Tukutuku database: An extended study

In 2004 [Kitchenham, B.A., Mendes, E., 2004a. Software productivity measurement using multiple size measures. IEEE Transactions on Software Engineering 30 (12), 1023-1035, Kitchenham, B.A., Mendes, E., 2004b. A comparison of cross-company and single-company effort estimation models for web applications. In: Proceedings Evaluation and Assessment in Software Engineering (EASE’ 04), pp. 47-55] (S1) investigated, using data on 63 Web projects, to what extent a cross-company cost model could be successfully employed to estimate development effort for single-company Web projects. Their effort models were built using Forward Stepwise Regression (SWR) and they found that cross-company predictions were significantly worse than single-company predictions. This study S1 was extended by Mendes and Kitchenham [Mendes, E., Kitchenham, B.A., 2004. Further comparison of cross-company and within company effort estimation models for web applications. In: Proceedings International Software Metrics Symposium (METRICS’04), Chicago, Illinois, September 11-17th, 2004. IEEE Computer Society, pp. 348-357] (S2), who used SWR and Case-based reasoning (CBR), and data on 67 Web projects from the Tukutuku database. They built two cross-company and one single-company models and found that both SWR cross-company models and CBR cross-company data provided predictions significantly worse than single-company predictions. Since 2004 another 83 projects were volunteered to the Tukutuku database, and recently used by Mendes et al. [Mendes, E., Di Martino, S., Ferrucci, F., Gravino, C., in press. Effort estimation: How valuable is it for a web company to use a cross-company data set, compared to using its own single-company data set? In: Proceedings of International World Wide Web Conference (WWW’07), Banff, Canada, 8-12 May] (S3), who partially replicated Mendes and Kitchenham’s study (S2), using SWR and CBR. They corroborated some of S2’s findings (SWR cross-company model and the CBR cross-company data provided predictions significantly worse than single-company predictions) however they replicated only part of S2. The objective of this paper (S4) is therefore to extend Mendes et al.’s work and fully replicate S2. We used the same dataset used in S3, and our results corroborated most of those obtained in S2. The main difference between S2 and our study was that one of our SWR cross-company models showed significantly similar predictions to the single-company model, which contradicts the findings from S2.     

Applying static analysis for automated extraction of database interactions in web applications

Database interactions are among the most essential functional features in web applications. Therefore, for the testing and maintenance of a web application, it is important that the web engineer could identify all the database interactions in the web application. However, the highly dynamic nature of web applications makes it challenging to extract all the possible database interactions from source code.In this paper, we propose an automated approach to extract database interactions from source code by using symbolic execution and inference rules. Our approach automatically identifies all the possible database interaction points. After that, all the program paths, which pass through each interaction point, are also computed. Each of these paths is then symbolically executed following our proposed symbolic evaluation rules. We also develop inference rules to deduce the interaction types from the set of symbolic expressions derived during the symbolic execution. Experiments have been conducted to evaluate the performance and usefulness of the proposed approach. The results indicate that even with some limitations in handling function calls, pointers and polymorphism, our approach still gives an average precision of 79.2%, which is 45.4% more than that of the conservative approach.     

Building test cases and oracles to automate the testing of web database applications

Many organizations rely on web applications that use back-end databases to store important data. Testing such applications requires significant effort. Manual testing alone is often impractical, so testers also rely on automated testing techniques. However, current automated testing techniques may produce false positives (or false negatives) even in a perfectly working system because the outcome of a test case depends on the state of the database which changes over time as data is inserted and deleted. The Automatic Database Tester (AutoDBT) generates functional test cases that account for database updates. AutoDBT takes as input a model of the application and a set of testing criteria. The model consists of a state transition diagram that shows how users navigate pages, a data specification that captures how data flows, and an update specification that shows how the database is updated. AutoDBT generates guard queries to determine whether the database is in a state conducive to performing and evaluating tests. AutoDBT also generates partial oracles to help validate whether a back-end database is updated correctly during testing. This paper describes the design of AutoDBT, a prototype implementation, several experiments with the prototype, and four case studies.     

Testing web applications

Traditional testing techniques are not adequate for web-based applications, since they miss their additional features such as their multi-tier nature, hyperlink-based structure, and event-driven feature. Limited work has been done on testing web applications. In this paper, we propose new techniques for white box testing of web applications developed in the .NET environment with emphasis on their event-driven feature. We extend recent work on modeling of web applications by enhancing previous dependence graphs and proposing an event-based dependence graph model. We apply data flow testing techniques to these dependence graphs and propose an event flow testing technique. Also, we present a few coverage testing approaches for web applications. Further, we propose mutation testing operators for evaluating the adequacy of web application tests.     

Web数据库在图书馆公共公务网中的应用研究

在分析和研究Web应用体系结构和Web数据库技术的基础上,提出了建立跨平台的Web技术的图书馆公共公务网的设计思想,通过网站向各图书馆提供业务服务功能,所有图书馆可以在该网站上建立自己的自动化系统,实现了图书馆业务管理系统网络化.讨论了图书馆公共公务管理系统中Web数据库的建立、连接、数据查询和安全访问等策略方法,给出了切实可行的解决方案.     

Top-k queries over web applications

The core logic of web applications that suggest some particular service, such as online shopping, e-commerce etc., is typically captured by Business Processes (BPs). Among all the (maybe infinitely many) possible execution flows of a BP, analysts are often interested in identifying flows that are “most important”, according to some weight metric. The goal of the present paper is to provide efficient algorithms for top-k query evaluation over the possible executions of Business Processes, under some given weight function. Unique difficulties in top-k analysis in this settings stem from (1) the fact that the number of possible execution flows of a given BP is typically very large, or even infinite in presence of recursion and (2) that the weights (e.g., likelihood, monetary cost, etc.) induced by actions performed during the execution (e.g., product purchase) may be inter-dependent (due to probabilistic dependencies, combined discount deals etc.). We exemplify these difficulties, and overcome them to provide efficient algorithms for query evaluation where possible. We also describe in details an application prototype that we have developed for recommending optimal navigation in an online shopping web site that is based on our model and algorithms.     

利用框架技术构建Web应用

目前开发基于Java的Web应用正逐渐转向开源框架支持的轻量级开发架构,基于框架的Web应用具有高可靠性、可复用性,可扩展性和可维护性等优点.当前主流的开源框架有Struts、Spring和Hibernate,其中Struts是一个优秀的MVC框架,Spring是以AOP为基础并实现了IoC机制的轻量级框架,Hibernate是实现了对象/关系映射的持久化框架,它们三者的整合是目前一个比较流行的开发架构.分别介绍这3个框架,然后介绍整合了它们的一个开发架构,并通过一个实际的例子说明了在应用中将它们整合的方法.     

基于Web数据库安全机制的研究

WWW的迅速发展,使得Web技术与数据库技术紧密结合,因此研究基于Web的数据库安全机制对于信息系统的安全保护有着很重要的实际意义。分析了目前常见的几种Web数据库的连接技术,详细地阐述了利用ASP相关技术来实现基于Web数据库安全机制的一种方法。     

Linux环境下Web数据库的图形统计

Web数据库的图形统计是目前尚未很好解决的一个问题。文中对Linux服务器环境下进Web数据库图形统计的方法进行了分析,重点研究了基于CGI,Java以及目前流行的Linux下的Web数据库开发工具PHP3实现Oracle Web数据库的图形统计的方案,并进行了分析比较。     

Building rich web applications with Ajax

Looks at how developers are going back to the future by building Web applications using Ajax (Asynchronous JavaScript and XML), a set of technologies mostly developed in the 1990s. A key advantage of Ajax applications is that they look and act more like desktop applications. Proponents argue that Ajax applications perform better than traditional Web programs. As an example, Ajax applications can add or retrieve new data for a page it is working with and the page will update immediately without reloading.     

语义Web应用研究综述

介绍了语义Web的关键技术XML、RDF(S)和本体,并指出了语义Web技术的众多应用领域:知识管理、语义搜索、P2P、电子商务、电子政务、语义网格、Web挖掘、语义Web服务,智能信息Agent和语义门户等.从这些领域当前面临的困难和挑战出发,分析和论述了语义Web技术在这些应用领域的作用、应用前景和部分研究成果.     

Perturbation-based user-input-validation testing of web applications

User-input-validation (UIV) is the first barricade that protects web applications from application-level attacks. Most UIV test tools cannot detect semantics-related vulnerabilities in validators, such as filling a five-digit number to a field that accepts a year. To address this issue, we propose a new approach to generate test inputs for UIV based on the analysis of client-side information. In particular, we use input-field information to generate valid inputs, and then perturb valid inputs to generate invalid test inputs. We conducted an empirical study to evaluate our approach. The empirical result shows that, in comparison to existing vulnerability scanners, our approach is more effective than existing vulnerability scanners in finding semantics-related vulnerabilities of UIV for web applications.     

面向Web应用的语义标注方法

提出了一种语义标注的方法来支持用户在网上的浏览活动.采用了基于参考本体转换技术的语义转换,它能够从语义上同类型的标注资源中提取特征.随着获取标注资源的模式建立用户意向模型,利用概率的方法识别用户意向.然后利用启发式函数量化具体用户意向和资源之间的相似度,从而达到用户在浏览语义异构网络信息空间时获取相关信息的目的.     

Dynamic web worker pool management for highly parallel javascript web applications

JavaScript web applications are improving performance mainly thanks to the inclusion of new standards by HTML5. Among others, web workers API allows multithreaded JavaScript web apps to exploit parallel processors. However, developers have difficulties to determine the minimum number of web workers that provide the highest performance. But even if developers found out this optimal number, it is a static value configured at the beginning of the execution. Because users tend to execute other applications in background, the estimated number of web workers could be non‐optimal, because it may overload or underutilize the system. In this paper, we propose a solution for highly parallel web apps to dynamically adapt the number of running web workers to the actual available resources, avoiding the hassle to estimate a static optimal number of threads. The solution consists in the inclusion of a web worker pool and a simple management algorithm in the web app. Even though there are co‐running applications, the results show our approach dynamically enables a number of web workers close to the optimal. Our proposal, which is independent of the web browser, overcomes the lack of knowledge of the underlying processor architecture as well as dynamic resources availability changes. Copyright © 2015 John Wiley & Sons, Ltd.     

A product-line architecture for web service-based visual composition of web applications

A web service-based web application (WSbWA) is a collection of web services or reusable proven software parts that can be discovered and invoked using standard Internet protocols. The use of these web services in the development process of WSbWAs can help overcome many problems of software use, deployment and evolution. Although the cost-effective software engineering of WSbWAs is potentially a very rewarding area, not much work has been done to accomplish short time to market conditions by viewing and dealing with WSbWAs as software products that can be derived from a common infrastructure and assets with a captured specific abstraction in the domain. Both Product Line Engineering (PLE) and Agile Methods (AMs), albeit with different philosophies, are software engineering approaches that can significantly shorten the time to market and increase the quality of products. Using the PLE approach we built, at the domain engineering level, a WSbWA-specific lightweight product-line architecture and combined it, at the application engineering level, with an Agile Method that uses a domain-specific visual language with direct manipulation and extraction capabilities of web services to perform customization and calibration of a product or WSBWA for a specific customer. To assess the effectiveness of our approach we designed and implemented a tool that we used to investigate the return on investment of the activities related to PLE and AMs. Details of our proposed approach, the related tool developed, and the experimental study performed are presented in this article together with a discussion of planned directions of future work.     

Visual development of database applications

An exclusively visual approach to the development of database applications is introduced. Graphical tools and techniques are designed to represent all components of an application system, and all phases of the development process. Data, constraints, queries, transactions and programs are all expressed graphically. Analysis, design, maintenance, and even inference are carried out using graphical techniques. The visual approach is expected to be most appropriate for end users, and it is likely to encourage end-user participation in application development.     

Functional development of database applications

A highly modular and uniformly functional development methodology for database applications is introduced. An event-oriented view of the database is adopted recording the observed events directly and treating the state of the environment as derived data. The relationship between the observed events and the derived state of the system is expressed using a purely functional language. The application systems in this environment are divided into their smallest possible components consisting of only functions and simple functional expressions. The multimode of small but highly independent components generated in this fashion are placed in the database along with the data, to utilize the database management system in maintaining the application system. The semantics of individual applications is captured within the data model serving those applications