Torsten Eymann

A Prototype for an Agent-Based Secure Electronic Marketplace Including Reputation-Tracking Mechanisms

Software agents will play a crucial role in the coming digital economy, but their reliability and honesty cannot be guaranteed by technical security mechanisms, such as encryption of messages and digital signing of documents, and entities that can sanction fraudulent behavior in open networks are still in a rudimentary stage. This article describes a reputation mechanism that records previous cooperation behavior of participants in agent-based markets and conveys this information to other software agents, thereby influencing the future behavior of participants. The mechanism has been prototypically implemented in the Avalanche multiagent system. The deployment of this reputation mechanism will help to exclude fraudulent software agents from market participation.

Catallaxy-based Grid markets

Grid computing has recently become an important paradigm for managing computationally demanding applications, composed of a collection of services. The dynamic discovery of services, and the selection of a particular service instance providing the best value out of the discovered alternatives, poses a complex multi-attribute n:m allocation decision problem, which is often solved using a centralized resource broker. To manage complexity, this article proposes a two-layer architecture for service discovery in such Application Layer Networks (ALN). The first layer consists of a service market in which complex services are translated to a set of basic services, which are distinguished by price and availability. The second layer provides an allocation of services to appropriate resources in order to enact the specified services. This framework comprises the foundations for a later comparison of centralized and decentralized market mechanisms for allocation of services and resources in ALNs and Grids.

A Framework for Trust and Reputation in Grid Environments

This paper examines the role of trust and reputation in Grid environments. As Grid technology becomes standardized and stable, business models are invented and increasingly applied, and economic implications can be observed. Asymmetrically distributed information may allow for opportunistic behavior of service providers or users who opportunistically exploit the information gap between providers and consumers on the quality of services. The paper takes up these economic issues by proposing a reputation-based conceptual framework for enabling future open Grid markets, to recommend the most promising Grid architecture and a corresponding reputation approach in a particular case.

The catallaxy approach for decentralized economic-based allocation in Grid resource and service markets

Efficient resource allocation in dynamic large-scale environments is one of the challenges of Grids. In centralized economic-based allocation approaches, the user requests can be matched to the fastest, cheapest or most available resource. This approach, however, shows limitations in scalability and in dynamic environments. In this paper, we explore a decentralized economic approach for resource allocation in Grid markets based on the Catallaxy paradigm. Catallactic agents discover selling nodes in the resource and service Grid markets, and negotiate with each other maximizing their utility by following a strategy. By means of simulations, we evaluate the behavior of the approach, its resource allocation efficiency and its performance with different demand loads in a number of Grid density and dynamic environments. Our results indicate that while the decentralized economic approach based on Catallaxy applied to Grid markets shows similar efficiency to a centralized system, its decentralized operation provides greater advantages: scalability to demand and offer, and robustness in dynamic environments.

Decentralized resource allocation in application layer networks

Application-layer networks (ALN) are software architectures that allow the provisioning of services requiring a huge amount of resources by connecting large numbers of individual computers. The ALN simulation project CATNET evaluates a decentralized mechanism for resource allocation in ALN, which is based on the economic paradigm of the Catallaxy, against a centralized mechanism using an arbitrator object. In both versions, software agents buy and sell network services and resources to and from each other. The economic model is based on self-interested maximization of utility and self-interested cooperation between agents. This article describes the design of money and message flows for centralized and decentralized coordination in both versions and shows preliminary results.

Self-organizing resource allocation for autonomic network

Application-layer networks (ALN) are software architectures that allow the provisioning of services requiring a huge amount of resources by connecting large numbers of individual computers, e.g. grids and P2P-networks. Self-organization, like proposed by the autonomic computing concept, might be the key to controlling these systems. The CATNET project evaluates a decentralized mechanism for resource allocation in ALN, based on the economic paradigm of the Catallaxy. The economic model is based on self-interested maximization of utility and self-interested cooperation between software agents, who buy and sell network services and resources to and from each other.

Decentralized vs. centralized economic coordination of resource allocation in grids

Application layer networks are software architectures that allow the provisioning of services requiring a huge amount of resources by connecting large numbers of individual computers, like in Grid or Peer-to-Peer computing. Controlling the resource allocation in those networks is nearly impossible using a centralized arbitrator. The network simulation project CATNET will evaluate a decentralized mechanism for resource allocation, which is based on the economic paradigm of the Catallaxy, against a centralized mechanism using an arbitrator object. In both versions, software agents buy and sell network services and resources to and from each other. The economic model is based on self-interested maximization of utility and self-interested cooperation between agents. This article describes the setup of money and message flows both for centralized and decentralized coordination in comparison.

Enabling usage control through reputation objects: a discussion on e-commerce and the internet of services environments

This paper discusses the meaning and the role of Trust and Reputation in Internet-of-Service and e-Commerce environments following a comparative case study. Both environments represent paradigms through which the Internet is seen as a huge infrastructure where electronic services or real products are traded on. In comparison to electronic commerce, participating in an Internet-of-Services can be full of risks for all participants. Even well known security mechanisms are not able to close all gaps of access and usage control. This paper discusses the concepts of trust and reputation and brings to light the relation between these concepts to security mechanisms, Service-Level-Agreements, and quality measurements in order to enable Usage Control. The proposed solution is based on our previous model of reputation objects. The discussion also introduces a new concept of what we call reputation auditing where quality processes are considered part of reputation management not the other way around.

A simulation of an economic, self-organising resource allocation approach for application layer networks

Application Layer Networks like Utility Grid Networks or Cloud Computing Systems, often depicted as large scale self-organising architectures using a shared infrastructure, will need innovative management approaches for controlling and matching services demand and supply. This article shows a self-organising resource allocation approach based on principles of the Catallaxy, an economic concept of F.A. von Hayek. The implementation uses a coevolutionary learning algorithm for adaptation of the agent strategy to the dynamic Application Layer Network environment. The simulation study performs a sensitivity analysis of a large scale Application Layer Network scenario with 2000 agents. A set of representative agents is selected and their evolutionary behaviour analysed.

On the Simulation of Grid Market Coordination Approaches

Grid computing has recently become an important paradigm for managing computationally demanding applications, composed of a collection of services. The dynamic discovery of services, and the selection of a particular service instance providing the best value out of the discovered alternatives, poses a complex multi-attribute n:m allocation decision problem, which is often solved using a central resource broker. However, decentralized approaches to this service allocation problem represent a much more flexible alternative, thus promising improvements in the efficiency of the resulting negotiations and service allocations. This paper compares centralized and decentralized service allocation mechanisms in Grid market scenarios according to a defined set of metrics.