Java-MaC: A Run-time Assurance Tool for Java Programs

We describe Java-MaC, a prototype implementation of the Monitoring and Checking (MaC) architecture for Java programs. The MaC architecture provides assurance about the correct execution of target programs at run-time. Monitoring and checking is performed based on a formal specification of system requirements. MaC bridges the gap between formal verification, which ensures the correctness of a design rather than an implementation, and testing, which only partially validates an implementation. Java-MaC provides a lightweight formal method solution as a viable complement to the current heavyweight formal methods. An important aspect of the architecture is the clear separation between monitoring implementation-dependent low-level behaviors and checking high-level behaviors against a formal requirements specification. Another salient feature is automatic instrumentation of executable codes. The paper presents an overview of the MaC architecture and a prototype implementation Java-MaC.     

基于因特网的连续媒体交互技术研究

对基于因特网的多媒体会议系统的传输特性、要求和协议标准等进行了系统地研究。通过对因特网上多媒体会议系统的特殊需求和支持多媒体网络协议存在问题的分析,提出了因特网多媒体会议系统的总体设计方案,并在此基础上对连续媒体中音频会议系统的实现进行了试验。     

Towards Monitoring-Oriented Programming: A Paradigm Combining Specification and Implementation

With the explosion of software size, checking conformance of implementation to specification becomes an increasingly important but also hard problem. Current practice based on ad-hoc testing does not provide correctness guarantees, while highly confident traditional formal methods like model checking and theorem proving are still too expensive to become common practice. In this paper we present a paradigm for combining formal specification with implementation, called monitoring-oriented programming (MoP), providing a light-weighted formal method to check conformance of implementation to specification at runtime. System requirements are expressed using formal specifications given as annotations inserted at various user selected places in programs. Efficient monitoring code using the same target language as the implementation is then automatically generated during a pre-compilation stage. The generated code has the same effect as a logical checking of requirements and can be used in any context, in particular to trigger user defined actions, when requirements are violated. Our proposal is language- and logic- independent, and we argue that it smoothly integrates other interesting system development paradigms, such as design by contract and aspect oriented programming. A prototype has been implemented for Java, which currently supports requirements expressed using past time and future time linear temporal logics, as well as extended regular expressions.     

基于IEEE802.15.4a的工业无线网络嗅探器

针对基于IEEE802.15.4a的工业无线传感器监控网络嗅探器的研究和实现,从分析嗅探器原理,介绍了IEEE802.15.4a协议,详细描述了嗅探器的系统结构及设计中对数据包的捕获和过滤过程。给出了针对4种不同过滤设置条件所对应的类定义,可根据用户要求对指定类型、特定站点或设定时间段及包含热点关键字的数据进行捕获过滤,动态显示网络的实时状况。经过试验,本嗅探器完全达到了设计要求,实现了对无线传感器网络的主动侦听监控。     

模型检测在软件需求分析及设计中的应用

模型检测技术因其完全自动化并且验证速度快的优点在硬件及协议的验证中广泛应用,近年来在软件领域的应用研究也不断涌现.总结了模型检测在软件需求分析及设计中已有的应用技术,包括利用模型检测工具对RSML,SCR和UML图形的检测,以及直接的模型检测,并从不同角度对已有技术进行系统的分析和比较.最后对该项技术研究的方向进行展望.     

基于SOPC的网络视频监控系统的设计

提出一种以Nios Ⅱ软核处理器为核心,利用SOPC技术构建硬件平台,采用H.263协议压缩视频数据的网络视频监控系统设计方案;详细分析了系统的功能需求,确定了系统设计的总体方案;按照模块化的思想,设计了各个功能模块,并给出了网络芯片DM9000A电路的具体实现,利用μClinux中的TCP/IP协议栈进行数据通信,分析H.263视频编码协议基本原理,提出在硬件上实现H.263协议的设计方法;实验结果显示系统的网络视频传输速率达到25～30fps,满足实时性的要求.本设计方法灵活、成本较低、易扩展,具有一定的实用价值.     

Java-MaC: A Run-Time Assurance Approach for Java Programs

We describe Java-MaC, a prototype implementation of the Monitoring and Checking (MaC) architecture for Java programs. The MaC architecture provides assurance that the target program is running correctly with respect to a formal requirements specification by monitoring and checking the execution of the target program at run-time. MaC bridges the gap between formal verification, which ensures the correctness of a design rather than an implementation, and testing, which does not provide formal guarantees about the correctness of the system.Use of formal requirement specifications in run-time monitoring and checking is the salient aspect of the MaC architecture. MaC is a lightweight formal method solution which works as a viable complement to the current heavyweight formal methods. In addition, analysis processes of the architecture including instrumentation of the target program, monitoring, and checking are performed fully automatically without human direction, which increases the accuracy of the analysis. Another important feature of the architecture is the clear separation between monitoring implementation-dependent low-level behaviors and checking high-level behaviors, which allows the reuse of a high-level requirement specification even when the target program implementation changes. Furthermore, this separation makes the architecture modular and allows the flexibility of incorporating third party tools into the architecture. The paper presents an overview of the MaC architecture and a prototype implementation Java-MaC.     

Enterprise Network Traffic Monitoring, Analysis, and Reporting Using Web Technology

Today's enterprise networks are composed of multiple types of interconnected networks. Furthermore, organizations use a variety of systems and applications on these networks. Operations and management staff must provide an efficient, reliable and secure operating environment to support an organization's daily activities. Enterprise networks must be monitored for performance, configuration, security, accounting and fault management. Current management practices typically involve the use of complex, hard-to-learn and hard-to-use tools. What is needed desperately is a set of simple, uniform, ubiquitous tools for managing networks. Web-based management promises to provide such solutions. This paper focuses on the use of Web technology and the Multi-Router Traffic Grapher (MRTG) for the purposes of enterprise network traffic monitoring and reporting. In this paper, we first examine the requirements for enterprise network traffic monitoring, analysis and reporting, and then present the design and implementation of a Web-based network traffic monitoring and reporting system that satisfies those requirements. We also present guidelines we have formulated and used for analyzing enterprise network traffic. We then discuss our experiences in using such a system for traffic monitoring on two large enterprise networks.     

电力变电站温度智能监测网络研究与实现

为实现电力系统变电站的温度场的无人职守智能监测的目的.采用无线传感器网络中典型的ZigBee技术应用于变电站的温度监测,完成了网络硬件节点的研究、设计和实现,满足节点低功耗的要求,在协议栈和通信协议方面,分析了ZigBee技术的节点网络地址分配特点.提出了适应于数据采集的自动路由算法;最后分析了节点功耗、采集时间延时和网络生命周期等性能表现,表明温度场智能监测网络可达到长时间无人值守实时监测的目的.     

Ad Hoc网络协议栈跨层自适应设计

针对Ad Hoc网络多变的网络特征和不同业务需求,介绍了Ad Hoc网络协议栈进行跨层自适应设计必要性,并对跨层设计概念、模型、机制、设计要求等方面进行阐述,提出了跨层设计的实现方式、实现方法、实现技术,最后总结跨层的优势及存在的问题。     

Adaptive congestion protocol: A congestion control protocol with learning capability

There is strong evidence that the current implementation of TCP will perform poorly in future high-speed networks. To address this problem many congestion control protocols have been proposed in literature which, however, fail to satisfy key design requirements of congestion control protocols, as these are outlined in the paper. In this work we develop an adaptive congestion protocol (ACP) which is shown to satisfy all the design requirements and thus outperform previous proposals. Extensive simulations indicate that the protocol is able to guide the network to a stable equilibrium which is characterized by max–min fairness, high-utilization, small queue sizes and no observable packet drops. In addition, it is found to be scalable with respect to changing bandwidths, delays and number of users utilizing the network. The protocol also exhibits nice transient properties such as smooth responses with no oscillations and fast convergence. In realistic traffic scenarios comprising of a small number of long flows and a large number of short flows, ACP outperforms both TCP and XCP, even in the presence of random packet losses. ACP does not require maintenance of per flow states within the network and utilizes an explicit multi-bit feedback signalling scheme. To maintain stability it implements at each link a novel estimation algorithm which estimates the number of flows utilizing the link. Using a simple network model, we show analytically the effectiveness of the estimation algorithm. We use the same model to generate phase portraits which demonstrate that the ACP protocol is stable for all delays.     

SNMP协议下的计算机网络监控管理系统开发研究

随着网络应用的逐步普及和深入,网络管理工作也变得越来越复杂。基于SNMP协议的计算机网络监控管理系统可以使网络可靠、高效地运行。本文阐述了SNMP协议下的网络监控管理系统开发过程,包括系统硬件结构设计、系统软件结构设计以及系统功能模块的实现。     

Monitoring, Checking, and Steering of Real-Time Systems

The MaC system has been developed to provide assurance that a target program is running correctly with respect to formal requirements specification. This is achieved by monitoring and checking the execution of the target program at run-time. MaC bridges the gap between formal verification, which ensures the correctness of a design rather than an implementation, and testing, which only partially validates an implementation. One weakness of the MaC system is that it can detect property violations but cannot provide any feedback to the running system. To remedy this weakness, the MaC system has been extended with a feedback capability. The resulting system is called MaCS (Monitoring and Checking with Steering). The feedback component uses the information collected during monitoring and checking to steer the application back to a safe state after an error occurs. We present a case study where MaCS is used in a control system that keeps an inverted pendulum upright. MaCS detects faults in controllers and performs dynamic reconfiguration of the control system using steering.     

移动支付协议PCMS的形式化分析和验证

移动电子商务协议的形式化分析和验证是近年来移动电子商务协议的一个重要研究热点。以一个支付网关为中心的匿名的移动电子商务支付协议PCMS为研究对象,建立了PCMS协议的时间自动机模型,并用计算树逻辑CTL公式描述PCMS协议的部分性质,最后利用模型检测工具UPPAAL对PCMS协议的无死锁、时效性、有效性和钱原子性进行检测验证。验证结果表明,以支付网关为中心的匿名的安全支付协议PCMS满足无死锁、时效性、有效性和钱原子性。     

基于SNMP协议校园网络管理系统设计与实现

结合高校校网络管理需求,通过对简单网络管理协议（SNMP）工作原理分析和研究,提出了基于SNMP协议网络管理系统的设计思路和编程实现方法。     

Design and Analysis of Sensing Scheduling Algorithms under Partial Coverage for Object Detection in Sensor Networks

Object detection quality and network lifetime are two conflicting aspects of a sensor network, but both are critical to many sensor applications such as military surveillance. Partial coverage, where a sensing field is partially sensed by active sensors at any time, is an appropriate approach to balancing the two conflicting design requirements of monitoring applications. Under partial coverage, we develop an analytical framework for object detection in sensor networks, and mathematically analyze average-case object detection quality in random and synchronized sensing scheduling protocols. Our analytical framework facilitates performance evaluation of a sensing schedule, network deployment, and sensing scheduling protocol design. Furthermore, we propose three wave sensing scheduling protocols to achieve bounded worst-case object detection quality. We justify the correctness of our analyses through rigorous proof, and validate the effectiveness of the proposed protocols through extensive simulation experiments     

无线通信在石油测井中的应用

无线通信应用于石油测井能够极大的提高测井效率，是石油测井未来的发展方向。本文分析了石油测井远程监测的基本要求，提出了一套无线数据传输的系统方案。在通信协议的设计和实现上，采用了双发送队列、优先级调度以及全双工滑动窗口协议等方法，同时保证了测井数据的实时传输和文件资料的正常交互，很好的满足了石油测井数据传输的要求。     

Formal Analysis of Streaming Downloading Protocol for System Upgrading

For a PC-mobile download system which is embedded with streaming download protocol, there are problems that the data cannot be transmitted correctly from the PC to the mobile, or the transmission is unacceptably slow. To solve these problems, we carry out a formal analysis for the protocol with some timing parameters and a given probability of message loss and unordered data using a probabilistic model checking tool PRISM. We introduce a technique to reduce the state space of the system modeling the protocol which is a network of probabilistic timed automata. The experimental results in PRISM give us a clear explanation to the problems, and are helpful in identifying the optimal parameter settings to meet industrial requirements.     

Mesh-Mon: A multi-radio mesh monitoring and management system

Mesh networks are a potential solution for providing communication infrastructure in an emergency. They can be rapidly deployed by first responders in the wake of a major disaster to augment an existing wireless or wired network. We imagine a mesh node with multiple radios embedded in each emergency vehicle arriving at the site to form the backbone of a mobile wireless mesh. The ability of such a mesh network to monitor itself, diagnose faults and anticipate problems are essential features for its sustainable operation. Typical SNMP-based centralized solutions introduce a single point of failure and are unsuitable for managing such a network. Mesh-Mon is a decentralized monitoring and management system designed for such a mobile, rapidly deployed, unplanned mesh network and works independently of the underlying mesh routing protocol. Mesh-Mon nodes are designed to actively cooperate and use localized algorithms to predict, detect, diagnose and resolve network problems in a scalable manner. Mesh-Mon is independent of the underlying routing protocol and can operate even if the mesh routing protocol completely fails. One novel aspect of our approach is that we employ mobile users of the mesh, running software called Mesh-Mon-Ami, to ferry management packets between physically-disconnected partitions in a delay-tolerant-network manner. The main contributions of this paper are the design, implementation and evaluation of a comprehensive monitoring and management architecture that helps a network administrator proactively identify, diagnose and resolve a range of issues that can occur in a dynamic mesh network. In experiments on Dart-Mesh, our 16-node indoor mesh testbed, we found Mesh-Mon to be effective in quickly diagnosing and resolving a variety of problems with high accuracy, without adding significant management overhead.     

Measures and mechanisms for process monitoring in evolving business networks

The literature on monitoring of cross-organizational processes, executed within business networks, considers monitoring only in the network formation phase, since network establishment determines what can be monitored during process execution. In particular, the impact of evolution in such networks on monitoring is not considered. When a business network evolves, e.g. contracts are introduced, updated, or dropped, or actors join or leave the network, the monitoring requirements of the network actors change as well. As a result, the monitorability of processes in the network may be disrupted. This paper proposes a framework to solve the problem of preserving the monitorability of processes in an evolving business network. We first propose a formal model of business networks, contracts, and monitoring requirements. Then, we model network evolution and the mechanisms to preserve the monitorability of the processes in the network for different types of evolution. In particular, the preservation of monitorability requires the actors in the network to take appropriate actions in case of dependencies between already established contracts, and update their monitoring infrastructure to satisfy the new monitoring requirements introduced by evolution. We also define a set of metrics that can be used for supporting decisions regarding the potential evolution of a business network. A case study in healthcare and the discussion of a prototype implementation show the applicability of our framework in real-world scenarios.