On performance evaluation and design of atomic commit protocols for mobile transactions

The challenges of wireless and mobile computing environments have attracted the attention of researchers to revisit the conventional transaction paradigm. Indeed, this paradigm is an indispensable asset in modern information systems. The atomicity property of a distributed transaction is ensured with the use of an atomic commit protocol (ACP). Due to their great importance for transaction systems, the recent advances in mobile computing development have renewed the interest in the design of ACPs for mobile systems. The work presented in this paper studies the impact of the various and fluctuant parameters of wireless and mobile systems on a set of ACPs for mobile environment. It highlights performance indices which give orientations to the design of an adaptable approach that supports different atomicity notions satisfying a wide range of applications and environment requirements.     

Experiences of Using Generative Communications to Support Adaptive Mobile Applications

Attention has recently begun to focus on the use of asynchronous paradigms to support adaptive mobile applications. To investigate this issue the authors have developed an asynchronous distributed systems platform based on the tuple space paradigm [19] coupled with extensions to support operation in mobile environments. This paper presents our experiences of developing and using this platform. The benefits of the tuple space approach are highlighted and we discuss in some detail the design, implementation and performance of our platform. We subsequently focus on the critical issues of the tuple space API and the level of support for adaptation which can be provided without compromising the elegance and simplicity of the paradigm. The paper concludes with an analysis of the suitability of platforms based on the tuple space paradigm for use in mobile environments.     

An election protocol based on group membership detection algorithm in mobile ad hoc distributed systems

The election model can be used as a composing element to solve many practical problems such as mutual exclusion, consensus problem and reliable broadcasting in which a control function would be useful. This model has been deeply examined in the study group since the motive for this much interest is that networked computer system paradigms require a coordinator such as leader. In spite of its importance, there is only a few study that has been contributed to this coordinator election model in an ad hoc distributed system. Mobile distributed computing systems are more inclined to faults than traditional computer systems. To build an election protocol in such a mobile computing environment is not trivial. Because it is difficult task to choose a unique process from a group of mobile processes as a coordinator in spite of failures or disconnections of mobile processes. In this paper, we present an election protocol in mobile ad hoc distributed systems and we discuss some simulation results.     

Autonomic tracing of production processes with mobile and agent-based computing

Tracing items in a supply chain, across different enterprises and through the full processes scope, is today an inherently complex design task. Enterprises are typically comprised of hundreds of applications that are custom built at different times, acquired from third parties and parts of legacy systems, and also operating in multiple tiers of different manufacturing and information system platforms. Further, traceability is characterized by a goal-oriented approach, in which business-process analyses are driven by goal achievements rather than by systematic engineering processes. The use of a classical enterprise integration approach mostly needs tailoring to different applications. Due to the number and diversity of the systems and of their interactions, and to their dynamicity, it is difficult, costly, and therefore often not convenient to develop in large scale distributed systems.To overcome these issues, a supply chain traceability system with a high level of automation is discussed in this paper. In particular, the system adopts an agent-based approach, in which cooperative software agents find solutions to back-end tracing problems by self-organization. Such cooperative agents are based on a business process aware traceability model, and on a service-oriented composition paradigm. Furthermore, an interface agent assists each user to carry out the front-end tracking activities. Interface agents rely on the context-awareness paradigm to gain self-configurability and self-adaptation of the user interface, and on ubiquitous computing technology, i.e., mobile devices and radio-frequency identification, to perform agile and automatic lot identification. The paper comprises real-world experiences on the fashion supply chain.     

MomentA: Service Management Using Mobile Agents in a CORBA Environment

This paper explores the mobility paradigm in the monitoring management of open distributed systems. A pool of monitoring mobile agents is defined to explore the managed environment based on a successive approach to potential problems. The implementation is performed using an open distributed environment based on CORBA objects. The use of mobile agents adds flexibility to the management task and the merge with static agents allows the scalability of the monitoring management.     

Specification and analysis of real-time systems with PARAGON

This paper describes a methodology for the specification and analysis of distributed real-time systems using the toolset called PARAGON. PARAGON is based on the Communicating Shared Resources paradigm, which allows a real-time system to be modeled as a set of communicating processes that compete for shared resources. PARAGON supports both visual and textual languages for describing real-time systems. It offers automatic analysis based on state space exploration as well as user-directed simulation. Our experience with using PARAGON in several case studies resulted in a methodology that includes design patterns and abstraction heuristics, as well as an overall process. This paper briefly overviews the communicating shared resource paradigm and its toolset PARAGON, including the textual and visual specification languages. The paper then describes our methodology with special emphasis on heuristics that can be used in PARAGON to reduce the state space. To illustrate the methodology, we use examples from a real-life system case study. This revised version was published online in June 2006 with corrections to the Cover Date.     

Distributed computing paradigms for collaborative signal and information processing in sensor networks

In this paper, we report the development of an energy-efficient, high-performance distributed computing paradigm to carry out Collaborative Signal and Information Processing (CSIP) in sensor networks using mobile agents. In this paradigm, the processing code is moved to the sensor nodes through mobile agents, in contrast to the client/server-based computing, where local data are transferred to a processing center. Although the client/server paradigm has been widely used in distributed computing, the many advantages of the mobile agent paradigm make it more suitable for sensor networks. The paper first presents simulation models for both the client/server paradigm and the mobile agent paradigm. We use the execution time, energy and energy*delay as metrics to measure the performance. Several experiments are designed to show the effect of different parameters on the performance of the paradigms. Experimental results show that the mobile agent paradigm performs much better when the number of nodes is large while the client/server paradigm is advantageous when the number of nodes is small. Based on this observation, we then propose a cluster-based hybrid computing paradigm to combine the advantages of these two paradigms. There are two schemes in this paradigm and simulation results show that there is always one scheme which performs better than either the client/server or the mobile agent paradigms. Thus, the cluster-based hybrid computing provides an energy-efficient and high-performance solution to CSIP.     

Using Assumptions to Distribute Alternation Free μ-Calculus Model Checking

In this work we extend the approach used in [6] to perform distributed-memory AFMC model checking. The part of a system held in one computer is modeled as a Kripke structure with border states. Moreover, we use assumptions about the truth of a formula in each state. Each process then repeatedly executes a slight modification of a standard sequential algorithm and exchanges its results with other processes. In the paper we define the AFMC semantics for structures with border states and assumptions, present the distributed algorithm and show the main ideas behind the proof of its correctness. Complexity and experimental results are provided as well.     

MASACAD: a multiagent based approach to information customization

MASACAD is a multiagent information customization system that adopts the machine-learning paradigm to advise students by mining the Web. In the distributed problem-solving paradigm, systems can distribute among themselves the processes necessary to accomplish a given task. Given the number of problems that distributed processing can address, AI researchers have directed significant effort toward developing specialized problem-solving systems that can interact in their search for a solution. The multiagent-system paradigm embodies this approach.     

一个基于CORBA和移动智能体的分布式网箱集成框架

文中分析了当前主流网管系统在体系结构上的缺陷,阐述了分布对象技术（CORBA）与移动智能体技术各自在网管领域的应用方法与优势。结合这些优势,给出了一个基于CORBA和移动智能体的分布式网管集成框架,并进一步通过实验模拟证实了其可行性。     

Linda meets Unix

The limitations of the shared-memory and distributed-memory models for explicit parallel programming are discussed and a new model, the Linda parallel communication paradigm which was designed specifically for parallel programming, is examined. Processes communicate in Linda by way of a shared data space called tuple space which acts something like an associative memory, since tuples are identified by matching on a key rather than using a specific address. This model is adapted for use as the basis of a new class of operating systems and a specific instance, QIX, is presented. Like Linda, this operating system model can support both the shared-memory and the distributed-memory styles of programming. Thus, it provides the benefits of both, while avoiding hardware dependencies. QIX also incorporates a novel scheme for name resolution that is easier to use than other methods and provides significant benefits in the operating system and it directly supports communication between programs written in different languages     

具有迁移能力的基于Agent分布仿真中的通信系统

对基于Agent系统的分布仿真是仿真领域的重要研究和应用方向，而分布仿真中的通信系统是其中的基础部分．提出并实现了一种支持基于Agent系统分布仿真的通信系统．该系统除了提供基本的仿真通信支持外，还能够有效地支持仿真中Agent的迁移，具有对应用系统透明、通信效率高等优点．首先给出了通信系统的结构及其基本思想，对局部服务Agent和通信过程进行了详细的描述；从应用系统级和分布仿真级两个层次，给出了结构化的通信协议；在此基础之上，给出了完整的Agent迁移支持方案，包括迁移过程、迁移过程中的消息处理和迁移后的通信；最后对通信系统的性能进行了测试．     

A new paradigm of cloud-based predictive maintenance for intelligent manufacturing

Advances in cloud computing reshape the manufacturing industry into dynamically scalable, on-demand service oriented, and highly distributed cost-efficient business model. However it also poses challenges such as reliability, availability, adaptability, and safety on machines and processes across spatial boundaries. To address these challenges, this paper investigates a cloud-based paradigm of predictive maintenance based on mobile agent to enable timely information acquisition, sharing and utilization for improved accuracy and reliability in fault diagnosis, remaining service life prediction, and maintenance scheduling. In the new paradigm, a low-cost cloud sensing and computing node is firstly developed with embedded Linux operating system, mobile agent middleware, and open source numerical libraries. Information sharing and interaction is achieved by mobile agent to distribute the analysis algorithms to cloud sensing and computing node to locally process data and share analysis results. Comparing to the commonly used client–server paradigm, the mobile agent approach enhances the system flexibility and adaptability, reduces raw data transmission, and instantaneously responds to dynamic changes of operations and tasks. Finally, the presented cloud-based paradigm of predictive maintenance is validated on a motor tested system.     

Adaptation in mobile workflow management systems

Workflow management systems (WFMS) are an emerging technology for supporting the coordinated execution of business processes by a group of users. One goal of introducing a WFMS into an enterprise is to integrate all personnel working on a business process into the system. This article describes a new approach to the integration of mobile users into a WFMS. This is of special interest because key personnel such as sales representatives and executives are often travelling and can only be integrated into the WFMS through mobile computing technologies. After introducing an architecture for mobile WFMS, we focus on the handling of one specific feature of mobile systems: the high diversity of environments in which mobile users operate. For handling this feature we have to implement adaptable software systems. In our approach, we start by introducing a formal model of mobile systems. This model offers a basis for the use of optimisation techniques to realise an adaptive mobile WFMS.     

Distributed computing using autonomous objects

Most existing distributed systems are structured as statically compiled processes communicating with each other via messages. The system's intelligence is embodied in the processes, while the messages contain simple, passive pieces of information. This is referred to as the communicating objects paradigm. In the autonomous objects paradigm, a message has its own identity and behavior. It decides at runtime where it wants to propagate and what tasks to perform there; the nodes become simply generic interpreters that enable messages to navigate and compute. In this scenario, an application's intelligence is embodied in and carried by messages as they propagate through the network. The autonomous objects paradigm is more flexible than the communicating objects paradigm because it allows developers to change the program's behavior after it has started to run. We based our system, MESSENGERS, on autonomous objects, and intended it for the composition and coordination of concurrent activities in a distributed environment. It combines powerful navigational capabilities found in other autonomous objects based systems with efficient dynamic linking mechanisms supported by some new programming languages, like Java     

移动组件系统模型的分析与描述

移动计算是新兴的分布式计算范型,其主要特征是计算组件与计算场所能动态改变绑定关系,表现出移动性,从而带来许多新的系统设计需求.从系统模型层次角度对位置、移动组件、移动和资源访问等移动计算核心概念,以及组件与位置之间的各种关系和关系变化刻画的移动范型进行了描述.通过使用集合论和操作语义的规约规则形式地表示这些概念、关系和移动机制,进而抽象出移动系统设计所需的语言结构,为移动系统设计和开发提供了分析基础.     

MAGDA: A Mobile Agent based Grid Architecture

Mobile agents mean both a technology and a programming paradigm. They allow for a flexible approach which can alleviate a number of issues present in distributed and Grid-based systems, by means of features such as migration, cloning, messaging and other provided mechanisms. In this paper we describe an architecture (MAGDA – Mobile Agent based Grid Architecture) we have designed and we are currently developing to support programming and execution of mobile agent based application upon Grid systems.     

Integrity protection for Code-on-Demand mobile agents in e-commerce

The mobile agent paradigm has been proposed as a promising solution to facilitate distributed computing over open and heterogeneous networks. Mobility, autonomy, and intelligence are identified as key features of mobile agent systems and enabling characteristics for the next-generation smart electronic commerce on the Internet. However, security-related issues, especially integrity protection in mobile agent technology, still hinder the widespread use of software agents: from the agent's perspective, mobile agent integrity should be protected against attacks from malicious hosts and other agents. In this paper, we present Code-on-Demand (CoD) mobile agents and a corresponding agent integrity protection scheme. Compared to the traditional assumption that mobile agents consist of invariant code parts, we propose the use of dynamically upgradeable agent code, in which new agent function modules can be added and redundant ones can be deleted at runtime. This approach will reduce the weight of agent programs, equip mobile agents with more flexibility, enhance code privacy and help the recoverability of agents after attack. In order to meet the security challenges for agent integrity protection, we propose agent code change authorization protocols and a double integrity verification scheme. Finally, we discuss the Java implementation of CoD mobile agents and integrity protection.     

MPI for Big Data: New tricks for an old dog

The processing of massive amounts of data on clusters with finite amount of memory has become an important problem facing the parallel/distributed computing community. While MapReduce-style technologies provide an effective means for addressing various problems that fit within the MapReduce paradigm, there are many classes of problems for which this paradigm is ill-suited. In this paper we present a runtime system for traditional MPI programs that enables the efficient and transparent out-of-core execution of distributed-memory parallel programs. This system, called BDMPI,¹ leverages the semantics of MPI’s API to orchestrate the execution of a large number of MPI processes on much fewer compute nodes, so that the running processes maximize the amount of computation that they perform with the data fetched from the disk. BDMPI enables the development of efficient out-of-core parallel distributed memory codes without the high engineering and algorithmic complexities associated with multiple levels of blocking. BDMPI achieves significantly better performance than existing technologies on a single node as well as on a small cluster, and performs within 30% of optimized out-of-core implementations.     

Stack splitting: A technique for efficient exploitation of search parallelism on share-nothing platforms

We study the problem of exploiting parallelism from search-based AI systems on share-nothing platforms, i.e., platforms where different machines do not have access to any form of shared memory. We propose a novel environment representation technique, called stack-splitting, which is a modification of the well-known stack-copying technique, that enables the efficient exploitation of or-parallelism from AI systems on distributed-memory machines. Stack-splitting, coupled with appropriate scheduling strategies, leads to reduced communication during distributed execution and effective distribution of larger grain-sized work to processors. The novel technique can also be implemented on shared-memory machines and it is quite competitive. In this paper we present a distributed implementation of or-parallelism based on stack-splitting including results. Our results suggest that stack-splitting is an effective technique for obtaining high performance parallel AI systems on shared-memory as well as distributed-memory multiprocessors.