Showing papers on "Contract Net Protocol published in 2005"

A multi-agent infrastructure and a service level agreement negotiation protocol for robust scheduling in grid computing

Abstract: In this paper we propose a new infrastructure for efficient job scheduling on the Grid using multi-agent systems and a Service Level Agreement (SLA) negotiation protocol based on the Contract Net Protocol. The agent-based Grid scheduling system involves user agents, local scheduler agents, and super scheduler agents. User agents submit jobs to Grid compute resources. Local scheduler agents schedule jobs on compute resources. Super scheduler agents act as mediators between the local scheduler and the user agents to schedule the jobs at the global level of the Grid. The SLA negotiation protocol is a hierarchical bidding mechanism involving meta-SLA negotiation between the user agents and the super scheduler agents; and sub-SLA negotiation between the super scheduler agents and the local scheduler agents. In this protocol the agents exchange SLA-announcements, SLA-bids, and SLA-awards to negotiate the schedule of jobs on Grid compute resources. In the presence of uncertainties a re-negotiation mechanism is proposed to re-negotiate the SLAs in failure.

A multiagent supply chain planning and coordination architecture

Abstract: A supply chain is a worldwide network of suppliers, manufactures, warehouses, distribution centers and retailers through which raw materials are acquired, transformed and delivered to customers. In recent years, a new system approach for managing the supply chain at the tactical and operational levels has emerged. It views a supply chain as composed of a set of intelligent (software) agents, who are responsible for one or more activities and interacting with other related agents in planning and executing their responsibilities. This paper presents a multiagent architecture of supply chain integration. Agents coordination using extended contract net protocol is discussed. Two types of bidding approaches, i.e., the customizing-type and webbing-type are introduced into the multiagent supply chain system. Finally, a heuristics and two programming models for the planning and coordination of demand-driven supply chains are suggested.

Distributed multi-robot coalitions through ASyMTRe-D

Abstract: This paper presents a distributed reasoning system, called ASyMTRe-D, which enables a team of robots to form coalitions to accomplish a multi-robot task through tightly-coupled sensor sharing. The theoretical foundation of the negotiation protocol is ASyMTRe, an approach we developed previously to synthesize task solutions according to the task requirements and the team composition. The goal of the ASyMTRe approach is to increase the task solution capabilities of heterogeneous multi-robot teams by changing the fundamental abstraction from the typical "task" abstraction to a "schema" abstraction and automatically reconfigure the schemas to address the task at hand. The decision-making in this prior work was fully centralized; the current paper presents a distributed version of this approach based on the contract net protocol, which can achieve higher levels of robustness than the centralized version. The purpose here is not to improve the original protocol, but to apply it to our problem so that the autonomous task solution capabilities of robots can be achieved in a distributed manner. Simulation results are provided to validate the protocol with performance analysis. Finally, we compare ASyMTRe-D with the centralized ASyMTRe. Our future objective is to enable the human designer to specify the desired balance between solution quality and robustness, enabling the reasoning approach to invoke the appropriate level of information-sharing among robots to reach the specified solution characteristics.

Performance enhancement of a contract net protocol based system through instance-based learning

Abstract: The contract net protocol (CNP) is a widely used coordination mechanism in multiagent systems. It has a lot of communication overhead due to the broadcast of the task announcements. The performance of the CNP degrades drastically when the number of communicating agents and the number of tasks announced increases. Hence, it has problems of scalability. In order to overcome this limitation, an instance-based learning (IBL) mechanism is designed that uses previously stored instances in order to select a target agent. This avoids the expensive bidding process. The scheme is implemented in a simulated distributed hospital system where the CNP is used for resource sharing across hospitals. Experimental results demonstrate that with the incorporation of the IBL, the system performance improves significantly. The system is better scalable with respect to the number of tasks.

Web-based distributed manufacturing control systems

Abstract: With the evolution of the application of web technology, agent-based manufacturing systems can be both easily implemented and become a potential approach for modern manufacturing enterprises. In this paper, we present problems and models required for the development of web-based distributed manufacturing control systems. The specific objectives are: (1) to propose an appropriate architecture for a web-based distributed manufacturing control system, (2) to define the specification of a web-based cell controller, (3) to design the co-operative mechanisms, contract net protocol, for better system performance, (4) to upgrade the communication capability of existing CNC machines from RS232C to TCP/IP (Transmission Control Protocol/Internet Protocol) based on Ethernet .

Building agent-based systems in a discrete-event simulation environment

Abstract: The paper outlines a discrete-event simulation environment for modeling agent-based manufacturing systems. Exploiting the advantages of a general discrete-event simulation package, in the developed system agent-based features are directly included in the simulation environment providing the possibility to build agent-based models inside the simulation. The paper describes the agent-based functionalities of the system by presenting the communication mechanisms and predefined collaboration protocols. The modeling system implements the heterarchical control concept that is based on the contract net protocol.

Controlled experimentation with agents : Models and implementations

Abstract: The deployment of multi-agent systems demands for justified confidence into their functioning, both with respect to correctness of behaviour and with respect to timeliness thereof. Depending on the stage of the development process different mechanisms and abstractions are needed to facilitate the evaluation of interacting agents. We propose a modelling and simulation framework based on a discrete-event formalism for supporting the development process of multi-agent systems; from specification to implementation. The framework allows for the incremental refinement of agents and experimental set-ups while providing rigorous observation facilities. The benefit of using discrete-event modelling and simulation techniques for evaluating agents is illustrated using a simple example based on the Contract Net Protocol.

Verified models of multiagent systems for vehicle health management

Abstract: A multiagent framework for data acquisition, analysis, and diagnosis in health management is proposed. It uses the contract net protocol, a protocol for high-level distributed problem solving that provides adaptive and flexible solutions where task decomposition and assignment of subtasks is natural. Java is used to wrap implementations of existing techniques for individual tasks, such as neural networks or fuzzy rule bases for fault classification. The Java wrapping supplies an agent interface that allows an implementation to participate in the contract net protocol. This framework is demonstrated with a simple Java prototype that monitors a laboratory specimen that generates acoustic emission signals due to fracture-induced failure. A multiagent system that conforms to our framework can focus resources as well as select important data and extract important information. Such a system is extensible and decentralized, and redundancy in it provides fault tolerance and graceful degradation. Finally, the flexibility inherent in such a system allows new strategies to develop on the fly. The behavior of a non-trivial concurrent system (such as multiagent systems) is too complex and uncontrollable to be thoroughly tested, so methods have been developed to check the design of a concurrent system against formal specifications of the system"s behavior. We review one such method-model checking with SPIN-and discuss how it can be used to verify control aspects of multiagent systems that conform to our framework.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Retractable Contract Network for Distributed Scheduling

Abstract: This paper is about distributed scheduling where individual agents have potentially conflicting interests. It is motivated by BT’s workforce scheduling problem, where multiple service providers have to serve multiple service buyers. The service providers and buyers all attempt to maximize their own utility. The overall problem is a multi-objective optimization problem; for example, one has to maximize completion rates and service quality and minimize travelling distances. In this paper, BT’s problem is modelled as an open constraint optimization system. Standard contract net is a practical strategy in distributed scheduling where agents may have conflicting objectives. In this paper, we have introduced a retractable contract net protocol, which we call RECONNET, that supports hill-climbing in the space of solutions. It is built upon a job-release and compensation mechanism. RECONNET is a general protocol, which could be used to implement complex meta-heuristic algorithms such as Tabu Search and Guided Local Search. A system based on RECONNET has been implemented for BT’s workforce scheduling problem. The software, which we call ASMCR, allows the management to have full control over the company’s multiobjectives. The manager generates a Pareto set of solution by defining, for each buyer and seller, the weights given to each objective. ASMCR gives service buyers and sellers ownership of their problem and freedom to maximize their performance under the criteria defined by the management. ASMCR took 5 to 15 minutes to complete when tested on real-sized problems. It has potential to be developed into practical solutions to BT’s workforce scheduling problem.

Passengers trips planning using contract-net with filters

Abstract: This work presents a mediated planning model for the scheduling of trip requests under a passenger transportation system. The approach is based on the contract net protocol plus a bids-filtering process. For the implementation was used an agent framework that can be easily extended to build different types of trips planning systems. Finally, our model with filters was confronted with centralized and decentralized optimization approaches. The first results show that in-between solutions can be obtained.

Contract net protocol using fuzzy case based reasoning

Abstract: This paper describes a new communication load reduction method ontask negotiation with Contract Net Protocol (CNP) in a multi-agent system. For coordination the agents, the CNP is widely used during the problem solving. But its performance degrades drastically when communicating agents and tasks increase. In order to overcome this problem, Fuzzy Case Based Reasoning (FCBR) is used in CNP, it can reduce the scope of competitors and communication load on task negotiation, make a distinct improvement to the efficiency. At the same time, in FCBR system a new cases maintaining method based on time-serial is proposed in order to ensure a better cooperation between agents and adapt to higher flexibility of system. Experimental results show the performance of the protocol based on FCBR improves significantly.

Contract nets for evaluating agent trustworthiness

Abstract: In this paper we use a contract net protocol in order to compare various delegation strategies. We have implemented some different agents, having a set of tasks to delegate (or to perform by themselves); the tasks are performed by the agents in a dynamic environment, that can help or worse their activity. The agent rely upon different strategies in order to choose whom to delegate. We implemented three classes of trustiers: a random trustier (who randomly chooses the trustee whom delegate the task to); a statistical trustier (who builds the trustworthiness of other agents only on the basis of their previous performances); a cognitive trustier (who builds a sophisticated and cognitively motivated trust model of the trustee, taking into account its specific features, its ability and motivational disposition, and the impact of the environment on its performance). Our experiments show the advantage of using cognitive representations.

Multi-agent system negotiation based on expanded contract net protocol research

Abstract: Multi-agent system (MAS) is an important research field of distributed artificial intelligence MAS negotiation is one of the key contents in MAS research Combining with traditional contract net protocol, acquaintance model, acquaintance coalition inner task allocation distributed optimization algorithm, bulletin board model of agent information exchange with different knowledge and agent mental state parameters, this paper presents a new multi-agent system negotiation model based on expanded contract net protocol and introduces the design and implementation of it in detail

Contract Net Model Based on Case Based Reasoning

Abstract: The contract net is an important model for problem solving based on the competitive mechanism and it does not place any limits on competitors in general, but the broadcast of the Task Announcement on Contract Net Protocol tends to consume much communication load,therefore it does not ensure the high efficiency. In order to achieve high performance and reduce cost of resource and communication,contract net protocol based on case based reasoning is presented, it can decrease the scope of competitors, make a distinct improvement to the efficiency. Several parameters such as forget coefficient、time coefficient and a special case are introduced into case based reasoning to ensure a better cooperation between agents and higher flexibility of system.

Multi-agent pursuit-evasion algorithm based on contract net interaction protocol

Abstract: The motivation is the deployment of large numbers of inexpensive robots in hostile environments to pursue evasive targets. Based on the interaction protocols of contract net and subscribe-publish, a distributive pursuit-evasion algorithm is proposed for multi-agents to pursue multiple evasive agents. The pursuit agents engaged in teams adopt a tail-chase strategy while the rest pursuit agents use a hug-a-tree policy. The evading agents move towards directions with fewer pursuit agents in their neighborhood. All agents communicate according to the subscribe-publish protocol and the pursuit agents coordinate their acts through the contract net protocol. The result of simulation under JADE platform shows that the pursuit agents can dynamically form several teams to catch respective evaders efficiently without centralized leadership or hierarchical coordination. Distributive in nature, it allows a large-scale agent fleet to perform complex tasks in a coordinated way.

Negotiation Protocol Inter Agents in an Electronic Market

Abstract: In this paper, we present a new environment of negotiation in a multi-agents system for the electronic market. Our environment presents two protocols of negotiation, namely; the protocol of negotiation by auction and the contract net protocol. The choice of the protocol to be used, is made according to the type of product negotiate, for certain products, we use the auction, and for others we use the technique of contract net protocol.

Task solving based on multi-agents cooperation in the environment of ABDIDSS

Abstract: As the classical decision support system(DSS) can not satisfy the requirement of complex and non-structuring decision problems,the agent-based distributed intelligent decision support system(ABDIDSS) is put forward which consists of some ABIDSSes in the various "Agent-Regions" connected through Internet.According to the knowledge provided by the "Agent-Region" in the ABDIDSS,the cooperation among multi-agents is divided into task-sharing cooperation and results-sharing cooperation while the former uses contract net protocol to realize the solving of tasks and sub-tasks among multi-agents and the latter uses partial global planning to realize cooperative solving of tasks among multi-agents.The processes and methods concerned with individual agent behavior control,cooperative solving of sub-tasks by agents in "Agent-Region" and solving of global tasks by agents in various "Agent-Regions" in the distributed environment are put forward in the environment of the ABDIDSS.

Contract generating server

Abstract: The invention concerns a contract server and a method for supporting an e-commerce contract arrangement between a vendor and a customer (61, 62, 63), wherein a terminal (51, 52, 53) assigned to the customer and a merchant server (31, 32, 33) assigned to the vendor exchange data for negotiating terms of such contract. The merchant server (31, 32, 33) transfers contract data specifying a set of contract terms of a contract to a third party's contract server (4). The contract server (4) generates a contract text specifying a contract that corresponds with the received contract data. Then, it transmits the contract text via a communication network 1 to a terminal (51, 52, 53) of the customer. The contract server executes an authentication procedure for authenticating the customer. If the contract server (4) receives a confirmation regarding the contract text from an authenticated customer, it stores the contract items as signed contract items.

Research on multi-agent based dynamic scheduling for job shops

Abstract: The control system of agile manufacturing systems should be capable of reconfiguring, communicating on webs, and cooperating with external systems Firstly proposed in the paper is a distributed multi-agent based manufacturing organization structure Then several traditional scheduling methods are compared,and the traditional Contract Net Protocol(CNP) and its limitation are discussed Finally,the procedure of manufacturing scheduling based on extended CNP is studied from two aspects of internal job-shops and inter-enterprises Especially,a multi-phase multi-task extended CNP aiming at task distribution among enterprises is designed

Network human-robot interface at service level

Abstract: Network human-robot interface is an important research topic. In home application, users access the robotic system directly via voice, gestures or through the network. Users explore a system by using the services provided by this system and to some extend users are enable to participate in a service as partners. A service may be provided by a robot, a group of robots or robots and other network connected systems (distributed sensors, information systems, etc). All these services are done in the network environment, where uncertainty such as the unstable network connection, the availability of the partners in a service, exists. Moreover, these services are controlled by several users, accessing at different time by different methods. Our research aimed at solving this problem to provide a high available level, flexible coordination system. In this paper, a multi-agent framework is proposed. This framework is validated by using our new concept of slave agents, a responsive multi-agent environment, a virtual directory facilitator (VDF), and a task allocation system using contract net protocol. Our system uses a mixed model between distributed and centralized model. It uses a centralized agent management system (AMS) to control the overall system. However, the partners and users may be distributed agents connected to the center through agent communication or centralized at the AMS container using the slave agents to represent the physical agents. The system is able to determine the task allocation for a group of robot working as a team to provide a service. A number of experiments have been conducted successfully in our lab environment using Issac robot, a PDA for user agent and a wireless network system, operated under our multi agent framework control. The experiments show that this framework works well and provides some advantages to existing systems.