A self-adaptation scheme for workflow management in multi-agent systems

Business processes, operational environment, variability of resources and user needs may change from time to time. An effective workflow management software system must be able to accommodate these changes. The ability to dynamically adapt to changes is a key success factor for workflow management systems. Holonic multi-agent systems (HMS) provide a flexible and reconfigurable architecture to accommodate changes based on dynamic organization and collaboration of autonomous agents. Although HMS provides a potential architecture to accommodate changes, the dynamic organization formed in HMS poses a challenge in the development of a new software development methodology to dynamically compose the services and adapt to changes as needed. This motivates us to study and propose a methodology to design self-adaptive software systems based on the HMS architecture. In this paper, we formulate a workflow adaptation problem (WAP) and propose an interaction mechanism based on contract net protocol (CNP) to find a solution to WAP to compose the services based on HMS. The interaction mechanism relies on a service publication and discovery scheme to find a set of task agents and a set of actor agents to compose the required services in HMS. We propose a viable self-adaptation scheme to reconfigure the agents and the composed services based on cooperation of agents in HMS to accommodate the changes in workflow and capabilities of actors. We propose architecture for our design methodology and present an application scenario to illustrate our idea.     

A dynamic scheme for scheduling complex tasks in manufacturing systems based on collaboration of agents

The characteristics of scheduling tasks in the real world is a dynamic and challenging issue as the processes and the companies involved may change from time to time. For small flexible enterprises to respond to business opportunities, an effective scheme to facilitate dynamic coalition, share the core competencies and resources and support inter-enterprise collaboration must be developed. Although multi-agent systems (MAS) provide a paradigm for modeling these characteristics, scheduling tasks in MAS is a complex problem due to the computational complexity involved, distributed architecture for scheduling tasks by individual agents and dependency of different agents’ workflows. How to develop a problem solver that can be applied in MAS to achieve coherent and consistent workflow schedules that can meet a customer’s order is an important issue. In this paper, we propose a solution methodology for scheduling workflows in MAS. Our solution combines the multi-agent system architecture to dynamically discover services, workflow and activity models to specify the capabilities of agents, contract net protocol to facilitate negotiation and coordination of agents and optimization theories to optimize the cost for fulfilling an order. A problem solver for scheduling tasks in MAS has been implemented. An application scenario has also been provided to verify our solution methodology.     

Development of context-aware workflow systems based on Petri Net Markup Language

The Petri Net Markup Language (PNML) is originally an XML-based interchange format for Petri nets. Individual companies may specify their process models in Petri nets and exchange the Petri nets with other companies in PNML. This paper aims to demonstrate the capabilities of PNML in the development of applications instead of an industrial interchange format only. In this paper, we apply PNML to develop context-aware workflow systems. In existing literature, different methodologies for the design of context-aware systems have been proposed. However, workflow models have not been considered in these methodologies. Our interests in this paper are to propose a methodology to automatically generate context-aware action lists for users and effectively control resource allocation based on the state of the workflow systems. To achieve these objectives, we first propose Petri net models to describe the workflows. Next, we propose models to capture resource activities. Finally, the interactions between workflows and resources are combined to obtain a model for the whole processes. Based on the combined model, we propose architecture to automatically generate context-aware graphical user interface to guide the users and control resource allocation in workflow systems. We demonstrate our design methodology using a health care example.     

虚拟企业环境下过程融合机制、模型及过程管理模式

提出虚拟企业产品设计过程融合的思想以及面向虚拟企业的设计过程融合与设计活动集成体系结构,该体系结构在任务分解与资源匹配、过程融合、设计任务执行以及对象与版本管理四个层次上捕捉设计过程中内在的动态特性。基于设计过程动态建模描述虚拟企业环境下过程融合设计流模型,支持虚拟企业环境下敏捷设计流管理,统一组织和管理设计过程、活动及其资源,实现虚拟企业环境下产品设计过程分析、优化与动态重构。     

The design of a JADE-based autonomous workflow management system for collaborative SoC design

Given a fast changing electronics goods marketplace, designers of integrated circuits and components need to be more competitive, efficient, flexible, and use collaborative workflow to reduce time-to-market and a project’s life cycle. In recent years, agent-based workflow management systems (WfMS) have been widely used to monitor and control business design processes. In this paper, intelligent agents are applied to the collaborative system-on-chip (SoC) design environment. The proposed JADE-based autonomous workflow management system (JAWMS) uses a workflow coordination mechanism and an agent integration mechanism to enable the analysis, management and interaction of automated design processes. The workflow coordination mechanism uses five domain specific agents to perform the workflow enactment services and a generic agent to control the system flow logic. The system kernel of JAWMS follows the specifications of the workflow reference model provided by the workflow management coalition (WfMC). The agent integration mechanism supports an agent to interact with other JADE-based agent platforms and to coordinate and monitor workflow coordination messages. All agents are written in the Java language using the JADE platform and work together to perform flexible, adaptive and dynamic design tasks in an autonomous and collaborative way. JAWMS facilitates SoC design and team interaction in a collaborative but distributed product development environment.     

科学工作流中基于上下文感知的资源访问控制

网格环境的动态性使得科学工作流执行过程中的资源访问控制成为一个重要的研究课题.因此,提出一种基于上下文感知的资源访问控制机制,对科学工作流的任务上下文及其约束进行了分析和定义.描述了基于上下文感知的资源访问控制算法,并在此基础上设计了基于上下文感知的科学工作流管理系统框架.最后,通过天气预报这个科学工作流实例验证了该算法.     

一种基于正关系的多Agent协调算法

多Agent之间的协调(coordination)与协作(cooperation)已经成为多Agent系统(multiagent system,MAS)中的一个关键问题。这是因为MAS的主要研究目标之一就是使得多Agent的信念、意图、期望、行为达到协调甚至协作。在开放、动态的MAS环境下,具有不同目标的多个Agent必须对其资源的使用以及目标的实现进行协调[1,4]。例如,在出现资源冲突时,若没有很好的协调机制,就有可能出现死锁。而在另一种情况下,当单个Agent无法独立完成目标,需要其它Agent帮助时,则需要协作。本文提出了一种基于正关系的多Agent协调机制和协调算法。在该算法中,通过使用这种协调机制,Agent能委托或接受交互中的子计划,从而形成系统负载均衡和有效降低系统运行开销。     

支持动态联盟的分布式工作流管理系统--AgentFlow

提出了一个支持动态联盟的工作流描述模型，在此基础上提出了一个基于Agent的分布式的软件体系结构，重点分析了基于多Agent的工作流管理系统中工作流的动态集成和工作流的执行。最后讨论了工作流的分布式协作监控。     

网格环境中基于移动Agent的工作流架构研究

传统的工作流架构有很多弱点,比如架构严重降低了系统性能,在动态环境中缺少灵活性。本文提出了一个集成了WebServices,网格,工作流和移动代理技术的分布式工作流架构。在这个架构中,我们可以通过移动代理间的通讯来达到工作流之间协同工作,而且这个架构增强了工作流的灵活性和可靠性。最后,以这个新的模型为基础实现了一个具体的工作流工作站。     

集成工作流与Multi-agents技术的供应链协同管理

提出了集成工作流与软件Agent技术的供应链协同管理框架及方法，通过工作流管理系统及多Agcnt的设计，应用XML描述的工作流过程规范，由软件Agent实时地执行和重置具体的工作流任务，从而达到供应链协调管理的目的。     

多Agent系统的上下文感知增强

如今,多agent系统(multi-agent system,简称MAS)被广泛用于开发各种应用系统.当前,开放、动态、难控的计算平台要求软件系统能够根据系统自身及其环境状态信息及其改变,动态地调节自身的行为,即具备一定的上下文感知能力.然而,现有工作并未就如何向既有的MAS应用系统引入上下文感知能力提出有效的解决方案.依照关注分离原则,结合面向上下文程序设计技术(context-oriented programming,简称COP)、反射技术(reflection)以及代码植入技术(code instrumentation),提出了一套MAS系统上下文感知增强框架和底层支撑技术.开发人员可以在既有应用源码不可得的情况下,自动地将指定agent类型转换为(扩展为)具有上下文感知能力的agent类型.此外,利用底层运行支撑环境,系统管理员可以在系统运行时刻动态地调整指定agent的上下文感知行为.     

A pluggable middleware architecture for developing context-aware mobile applications

The proliferation of powerful smartphone devices provides a great opportunity for context-aware mobile applications becoming mainstream. However, we argue that conventional software development techniques suffer because of the added complexity required for collecting and managing context information. This paper presents a component-based middleware architecture which facilitates the development and deployment of context-aware applications via reusable components. The main contribution of this approach is the combination of a development methodology with the middleware architecture, which together bring significant value to developers of context-aware applications. Further contributions include the following: The methodology utilizes separation of concerns, thus decreasing the developmental cost and improving the productivity. The design and implementation of context-aware applications are also eased via the use of reusable components, called context plug-ins. Finally, the middleware architecture facilitates the deployment and management of the context plug-ins in a resource-aware manner. The proposed methodology and middleware architecture are evaluated both quantitatively and qualitatively.     

Design and implementation of economics-based resource management system in ad hoc grid

The ad hoc grid is a spontaneous organization of cooperating heterogeneous nodes into a logical community without a fixed infrastructure and with only minimal administrative requirements. Resource management for ad hoc grids is challenging due to the participation of heterogeneous, dynamic, autonomous and ephemeral grid nodes. The paper proposes an ad hoc grid resource management system, the producers and consumers of ad hoc grid resource are modeled as the self-interested decision-makers described in microeconomic theory. All market participants in the ad hoc grid environment including grid resources and services can be represented as agents. We apply economic agents to build ad hoc grid resource management, where ad hoc grid resource consumers and providers can buy and sell ad hoc grid resource based on an underlying economic architecture. The main processes involved in ad hoc grid resource management are resource registration, discovery, and resource allocation. The experiments are conducted to compare ad hoc grid resource allocation algorithm with other ad hoc grid resource allocation algorithm. Simulation results show that our proposed algorithm is more efficient than compared allocation scheme.     

MaNEA: A distributed architecture for enforcing norms in open MAS

Norms have been promoted as a coordination mechanism for controlling agent behaviours in open MAS. Thus, agent platforms must provide normative support, allowing both norm-aware and non-norm-aware agents to take part in MAS that are controlled by norms. In this paper, the most relevant proposals on the definition of norm enforcement mechanisms are analyzed. These proposals present several drawbacks that make them unsuitable for open MAS. In response to these problems, this paper describes a new Norm-Enforcing Architecture aimed at controlling norms in open MAS. Specifically, this architecture supports the creation and deletion of norms on-line as well as the dynamic activation and expiration of instances. Finally, it can dynamically adapt to different scale MAS. The efficiency of this architecture has been experimentally evaluated and the results are shown in this paper.     

基于Multi-agent的轻量级工作流系统

讨论了采用multi-agent技术和轻量级理念设计的工作流系统,并给出了工作流系统结构的具体表示、任务分解和资源分配的方法。提出了一种在多Agent中基于ontology信息的传递方法,减轻了工作流中通信的负担,并解析了该系统框架的功能,说明了系统的优势,介绍了系统的实现方案。     

Mbalancer:虚拟机内存资源动态预测与调配

在现代数据中心,虚拟化技术在资源管理、服务器整合、提高资源利用率等方面发挥了巨大的作用,已成为云计算架构中关键的抽象层次和重要的支撑性技术。在虚拟化环境中,如果要保证高资源利用率和系统性能,必须有一个高效的内存管理方法,使得虚拟机的物理内存大小能够满足应用程序不断变化的内存需求。因此,如何在单机以及数据中心内进行内存资源的动态调控,就成为了一个关键性问题。实现了一个低开销、高精确度的内存工作集跟踪机制,进而进行相应的本地或者全局的内存调控。采用了多种动态内存调控技术：气球技术能够在单机内有效地为各个虚拟机动态调节内存;远程缓存技术可在物理机之间进行内存调度;虚拟机迁移可将虚拟机负载在多个物理主机间进行均衡。深入分析了以上各种方案的优缺点,并根据内存超载的情况有针对性地设计了相应的调控策略,实验数据表明：所提出的预测式的内存资源管理方法能够对内存资源进行在线监控和动态调配,并有效地提高了数据中心的内存资源利用率,降低了数据中心能耗。     

区分服务网络域内定性服务的动态配置

提出了一种新型的区分服务（DiffServ)网络域内定性服务的动态配置方案,即在网络入口点对聚合通信流进行分类、调节;在域内节点上动态测量定性服务业务流的特性,并相应调整资源分配参数,讨论了方案体系结构、实现过程和技术,并给出了初步的实验结果。     

面向服务的MAS组织模型与控制策略

在分析研究面向服务的体系结构和分布式人工智能基础上,设计了面向服务的MAS组织管理模型;阐述了MAS的集散管理模式、管理策略与机制;分析了MAS的协调控制特点及形式;提出了多级协调控制的协调策略。     

Multi-agent Mediator architecture for distributed manufacturing

A generic Mediator architecture for distributed task planning and coordination has been developed using multi-agent paradigms. In this approach, agents function autonomously as independent computing processes, and dynamic virtual clusters coordinate the agent's activities and decision making. This coordination involves dynamically created coordination agents and resource agents concurrently. The Mediator architecture contains three levels of these coordination agents: the template mediator, the data-agent manager, and the active mediator. The template mediator is the top-level global coordinator. This agent contains both the templates and the cloning mechanism to create the successively lower-level agents. Task plans are decomposed successively into subtasks, which are allocated to dynamically created agent clusters coordinated through data-agent managers and active mediators. Coordination of agent activity takes place both among the clusters and within each cluster. The system dynamically adapts to evolving manufacturing tasks, with virtual agent clusters being created as needed, and destroyed when their tasks are completed. The mediator architecture and related mechanisms are demonstrated using an intelligent manufacturing scheduling application. Both the machines and the parts involved in this production system are considered as intelligent agents. These agents use a common language protocol based on the Knowledge Query Manipulation Language (KQML). The generic Mediator approach can be used for other distributed organizational systems beyond the intelligent manufacturing application it was originally developed for.     

A workflow management system based on intelligent collaborative objects

This paper describes an architecture for workflow management systems based on Workflow Intelligent Business Objects (WIBOs). The design of WIBOs is based on principles of intelligence, autonomy, collaboration and co-operation. Using WIBOs that carry out tasks on users’ behalf, it is possible to build workflow systems that bring further improvements in process automation and dynamic management, and achieve dynamic (re)allocation of resources to Actors. A WIBO prototype architecture has been implemented using Java. A Java Remote Method Invocation (RMI) has been used to enable WIBOs to communicate over an Intranet or Internet.