基于解析树的Java Web灰盒模糊测试

由于Java Web应用业务场景复杂,且对输入数据的结构有效性要求较高,现有的测试方法和工具在测试Java Web时存在测试用例的有效率较低的问题.为了解决上述问题,本文提出了基于解析树的Java Web应用灰盒模糊测试方法.首先为Java Web应用程序的输入数据包进行语法建模创建解析树,区分分隔符和数据块,并为解析树中每一个叶子结点挂接一个种子池,隔离测试用例的单个数据块,通过数据包拼接生成符合Java Web应用业务格式的输入,从而提高测试用例的有效率;为了保留高质量的数据块,在测试期间根据测试程序的执行反馈信息,为每个数据块种子单独赋予权值;为了突破深度路径,会在相应种子池中基于条件概率学习提取数据块种子特征.本文实现了基于解析树的Java Web应用灰盒模糊测试系统PTreeFuzz,测试结果表明,该系统相较于现有工具取得了更好的测试准确率.     

Developing Java applications for a nuclear fusion experiment: a test case for Java applicability in a demanding environment

The paper describes the experience gained in the development of Java applications in a nuclear fusion experiment. Two Java tools for graphical data display and experiment configuration set‐up are presented as case studies. Based on these tools, the results derived by the application of some metrics for object oriented software and by the analysis of the design patterns imported in the applications are presented to highlight the effective code reuse achieved with Java. The main issues in the applicability of Java in a demanding environment are then introduced and a few weaknesses of the language are finally discussed. Copyright © 2001 John Wiley & Sons, Ltd.     

Dynamically adapting to system load and program behavior in multiprogrammed multiprocessor systems

Parallel execution of application programs on a multiprocessor system may lead to performance degradation if the workload of a parallel region is not large enough to amortize the overheads associated with the parallel execution. Furthermore, if too many processes are running on the system in a multiprogrammed environment, the performance of the parallel application may degrade due to resource contention. This work proposes a comprehensive dynamic processor allocation scheme that takes both program behavior and system load into consideration when dynamically allocating processors. This mechanism was implemented on the Solaris operating system to dynamically control the execution of parallel C and Java application programs. Performance results show the effectiveness of this scheme in dynamically adapting to the current execution environment and program behavior, and that it outperforms a conventional time‐shared system. Copyright © 2002 John Wiley & Sons, Ltd.     

GMarte: Grid middleware to abstract remote task execution

Grid computing technologies are now being largely deployed with the widespread adoption of the Globus Toolkit as the industrial standard Grid middleware. However, its inherent steep learning curve discourages the use of these technologies for non‐experts. Therefore, to increase the use of Grid computing, it is important to have high‐level tools that simplify the process of remote task execution. In this paper we introduce a middleware, developed on top of the Java Commodity Grid, which offers an object‐oriented, user‐friendly application programming interface, from the Java language, which eases remote task execution for computationally intensive applications. Copyright © 2006 John Wiley & Sons, Ltd.     

Studying energy trade offs in offloading computation/compilation in Java-enabled mobile devices

Java-enabled wireless devices are preferred for various reasons. For example, users can dynamically download Java applications on demand. The dynamic download capability supports extensibility of the mobile client features and centralizes application maintenance at the server. Also, it enables service providers to customize features for the clients. In this work, we extend this client-server collaboration further by offloading some of the computations (i.e., method execution and dynamic compilation) normally performed by the mobile client to the resource-rich server in order to conserve energy consumed by the client in a wireless Java environment. In the proposed framework, the object serialization feature of Java is used to allow offloading of both method execution and bytecode-to-native code compilation to the server when executing a Java application. Our framework takes into account communication, computation, and compilation energies to decide where to compile and execute a method (locally or remotely), and how to execute it (using interpretation or just-in-time compilation with different levels of optimizations). As both computation and communication energies vary based on external conditions (such as the wireless channel state and user supplied inputs), our decision must be done dynamically when a method is invoked. Our experiments, using a set of Java applications executed on a simulation framework, reveal that the proposed techniques are very effective in conserving the energy of the mobile client.     

MERPSYS: An environment for simulation of parallel application execution on large scale HPC systems

In this paper we present a new environment called MERPSYS that allows simulation of parallel application execution time on cluster-based systems. The environment offers a modeling application using the Java language extended with methods representing message passing type communication routines. It also offers a graphical interface for building a system model that incorporates various hardware components such as CPUs, GPUs, interconnects and easily allows various formulas to model execution and communication times of particular blocks of code. A simulator engine within the MERPSYS environment simulates execution of the application that consists of processes with various codes, to which distinct labels are assigned. The simulator runs one Java thread per label and scales computations and communication times adequately. This approach allows fast coarse-grained simulation of large applications on large-scale systems. We have performed tests and verification of results from the simulator for three real parallel applications implemented with C/MPI and run on real HPC clusters: a master-slave code computing similarity measures of points in a multidimensional space, a geometric single program multiple data parallel application with heat distribution and a divide-and-conquer application performing merge sort. In all cases the simulator gave results very similar to the real ones on configurations tested up to 1000 processes. Furthermore, it allowed us to make predictions of execution times on configurations beyond the hardware resources available to us.     

JESSICA: Java-Enabled Single-System-Image Computing Architecture

JESSICA stands for Java-enabled single-system-image computing architecture, a middleware that runs on top of the standard UNIX operating system to support parallel execution of multithreaded Java applications in a cluster of computers. JESSICA hides the physical boundaries between machines and makes the cluster appear as a single computer to applications—a single system image. JESSICA supports preemptive thread migration, which allows a thread to freely move between machines during its execution, and global object sharing through the help of a distributed shared-memory subsystem. JESSICA implements location-transparency through a message-redirection mechanism. The result is a parallel execution environment where threads are automatically redistributed across the cluster for achieving the maximal possible parallelism. A JESSICA prototype that runs on a Linux cluster has been implemented and considerable speedups have been obtained for all the experimental applications tested.     

Developing and distributing network based engineering solutions

The need to have easy access to the solutions of a variety of frequently occurring engineering problems, has resulted in the development of a wealth of tools ranging from engineering handbooks to sophisticated desktop engineering software. In this paper, we examine the use of internet/intranet-based methods for providing the tools that are commonly needed by engineers in their daily work. Using the World Wide Web as the distribution medium and the Internet browser as the execution environment, Sun Microsystem's Java technology provides the foundation for the development of an Engineer's Tool Box (ETB) that provides a framework whereby independent engineering software tools are linked, managed, and accessed globally via the Internet. Individual applications are developed to address specific engineering problems using simple, straightforward interfaces and are linked into the distributed ETB framework to solve more complex problems. The capabilities and limitations of the Java platform for developing and supporting such Internet based distributed engineering software tools are discussed herein.     

Improving static resolution of dynamic class loading in Java using dynamically gathered environment information

In Java software, one important flexibility mechanism is dynamic class loading. Unfortunately, the vast majority of static analyses for Java treat dynamic class loading either unsoundly or too conservatively. We present a novel semi-static approach for resolving dynamic class loading by combining static string analysis with dynamically gathered information about the execution environment. The insight behind the approach is that dynamic class loading often depends on characteristics of the environment that are encoded in various environment variables. Such variables are not static elements; however, their run-time values typically remain the same across multiple executions of the application. Thus, the string values reported by our technique are tailored to the current installation of the system under analysis. Additionally, we propose extensions of string analysis to increase the number of sites that can be resolved purely statically, and to track the names of environment variables. An experimental evaluation on the Java 1.4 standard libraries shows that a state-of-the-art purely static approach resolves only 28% of non-trivial sites, while our approach resolves 74% of such sites. We also demonstrate how the information gained from resolved dynamic class loading can be used to determine the classes that can potentially be instantiated through the use of reflection. Our extensions of string analysis greatly increase the number of resolvable reflective instantiation sites. This work is a step towards making static analysis tools better equipped to handle the dynamic features of Java. This material is based upon work supported by the National Science Foundation under CAREER grant CCF-0546040.     

A Platform-Independent Distributed Runtime for Standard Multithreaded Java

JavaSplit is a portable runtime environment for distributed execution of standard multithreaded Java programs. It gains augmented computational power and increased memory capacity by distributing the threads and objects of an application among the available machines. Unlike previous works, which either forfeit Java portability by using a nonstandard Java Virtual Machine (JVM) or compromise transparency by requiring user intervention in making the application suitable for distributed execution, JavaSplit automatically executes standard multithreaded Java on any heterogenous collection of Java-enabled machines. Each machine carries out its part of the computation using nothing but its local standard (unmodified) JVM. Neither the programmer nor the person submitting the program for execution needs to be aware of JavaSplit or its distributed nature. We evaluate the efficiency of JavaSplit on several combinations of operating systems, JVM implementations, and communication hardware.     

JASAG: a gridification tool for agricultural simulation applications

The Grid Computing paradigm aims to create a ‘virtual’ and powerful single computer with many distributed resources to solve resource intensive problems. The term ‘gridification’ involves the process of transforming a conventional application to run in a Grid environment. In that sense, the more automatic this process is, the easier is for developers with low expertise in parallel and distributed computing to take advantage of these resources. To date, many semiautomatic gridifiers were built to support different gridification approaches and application code structures or anatomies. Furthermore, agricultural simulation applications have a particular common anatomy based on biophysical entities, such as animals, crops, and pastures, which are updated by actions, such as growing animals, growing crops, and growing pastures, along simulation execution. However, this anatomy is not fully supported by any of the existing gridifiers. Thus, this paper presents Agricultural Simulation Applications Gridifier (ASAG), a method for easy gridification of agricultural simulation applications, and its Java implementation, named Java ASAG (JASAG). The main design drivers of JASAG are middleware independence, separation of business logic and Grid behavior, and performance increase. An experimental evaluation showing the feasibility of the gridification method and its implementation is also reported, which resulted in speedups of up to 25 by using a real agricultural simulation application. Copyright © 2014 John Wiley & Sons, Ltd.     

并发Java程序动态分析及重演技术研究

Java语言在并发程序方面的广泛应用对软件测试提出了新的挑战。众所周知,由于并发程序的不确定性,使得并发程序的设计、开发、调试和测试都非常困难。文章介绍了Safepro／Java中的多线程测试技术,通过对Java源程序进行适当的修改并且保持语义不变,跟踪并发Java程序的运行过程,收集有关数据并对数据进行分析,最终控制并发Java程序的重演。     

Byte-code scheduling of Java programs with branches for desktop grid

A method for an introductory optimization of multithreaded Java programs for execution on clusters of Java Virtual Machines (JVMs) inside desktop grids is presented. It is composed of two stages. In the first stage, a clustering algorithm is applied to extended macro data flow graphs generated on the basis of the byte-code compiled for multithreaded Java programs. These graphs account for data and control dependencies in programs including conditional branch instructions annotated by branch statistics driven from execution traces for representative sets of data. In the second stage, a list scheduling is performed based on the Earliest Task First (ETF) heuristics in which node mapping on JVMs accounts for mutually exclusive paths outgoing from conditional branch nodes. The presented object placement optimization algorithm is a part of the DG-ADAJ environment.     

Schedulable garbage collection in CLI virtual execution system

Virtual software execution environment, known as Virtual Machine (VM), has been gaining popularity through Java Virtual Machine (JVM) and Common Language Infrastructure (CLI). Given their advantages in portability, productivity, and safety, etc., applying VM to real-time embedded systems can leverage production cost, fast time-to-market, and software integrity. However, this approach can only become practical once the VM operations and application tasks are made schedulable jointly. In this paper, we present a schedulable garbage collection algorithm applicable on real-time applications in CLI virtual machine environment. To facilitate the scheduling of real-time applications and garbage collection operations, we make the pause time due to garbage collection controllable, and the invocation of garbage collection predictable. To demonstrate the approach, a prototype for a schedulable garbage collection has been implemented in CLI execution environment. The garbage collection is carried out by a concurrent thread while meeting a targeted pause time and satisfying the memory requests of applications. A cost model of garbage collection is established based on measured WCET such that the execution time and overhead of garbage collection operations can be predicted. Finally, we illustrate a joint scheduling algorithm to meet the time and memory constraints of real-time systems.     

MS-3监测系统对Java多线程程序的监测

多线程是Java语言的重要特点之一，但是Java语言的线程调度是由操作系统来完成的，开发人员无法获知各线程的具体执行情况，而常规的软件调试工具对线程的分析会对目标程序有较大的干扰。该文利用基干事件的混合监测系统MS-3，对Java多线程程序的各线程行为进行了精确的分析。     

性能监控框架Jwebap的研究与改进

基于Java开发的企业级应用系统中存在的性能问题一直是关注的热点。当网络环境、机器物理配置等外在条件足够优等从而不会影响系统性能时,系统内在的服务端方法执行时间长短就成为解决系统性能问题的关键。只有通过分析方法执行耗时,才能定位出耗时长的具体服务方法以便分析解决。在目前的性能监控工具中,开源Jwebap监控框架基于字节码注入技术高效的实现了对方法耗时和数据库执行耗时的监控。本文主要分析Jwebap工具的架构及实现原理,阐述了架构中所使用的ASM字节码注入机制和Trace追踪机制,并完善该框架,扩展实现了方法树以及SQL与方法的关联。最后通过测试比较该框架对系统性能的影响,根据测试结果对框架使用提出建议。     

Adaptability mechanisms for autonomic system implementation with AAOP

This paper presents a new approach to implementing an adaptability loop in Autonomic Computing (AC) systems, which is based on adaptable aspects. The approach utilizes the concept of adaptable aspect‐oriented programming (AAOP) in which a set of AOP aspects is used to run an application in the manner specified by its adaptability strategy. We present a model execution environment based on this concept, enabling the execution of applications with applied adaptability strategies. In the AAOP‐based AC system, the application is instrumented with aspects selected by the system from a set of all available aspects (sensors, effectors, and goal aspects) in such a way that the system can monitor and manage the application. This model can be used to implement systems that are able to monitor an application and its execution environment, and perform actions such as changing the current set of non‐functional constraints in response to changes in the application or its environment. The model can be used for various types of non‐functional goals, in various programming languages, both in centralized and distributed environments. This paper describes its Java‐based implementation and non‐functional goals referring to resource management. As a consequence, the application uses resources in a way specified in its adaptability strategy. Resource consumption management logic is transparent for the application, meaning that no modifications in the application source code are needed. Copyright © 2010 John Wiley & Sons, Ltd.     

JASMINE: A Java Tool for Multimedia Collaboration on the Internet

Although collaboration tools have existed for a long time [8], Internet-based multimedia collaboration has recently received a lot of attention mainly due to easy accessibility of the Internet by ordinary users. The Java platform and programming language has also introduced yet another level of easy access: platform-independent computing. As a result, it is very attractive to use Java to design multimedia collaboration systems for the Internet. Today there are many systems, which use Java for multimedia collaboration. However, most of these systems require the shared Java application to be re-written according to the collaboration system's Application Programming Interface (API)—a task which is sometimes difficult or even impossible. In this paper, we describe a practical approach for transparent collaboration with Java. Our approach is transparent in that the Java application can be shared as is with no modifications. The main idea behind our system is that user events occurring through the interactions with the application can be caught, distributed, and reconstructed, hence allowing Java applications to be shared transparently. Our architecture allows us to make the huge installed base of Java applications collaborative, without any modification to their original code. We also prove the feasibility of our architecture by implementation of the JASMINE¹ prototype.