Hein Meling

Anthill: a framework for the development of agent-based peer-to-peer systems

Recent peer-to-peer (P2P) systems are characterized by decentralized control, large scale and extreme dynamism of their operating environment. As such, they can be seen as instances of complex adaptive systems (CAS) typically found in biological and social sciences. We describe Anthill, a framework to support the design, implementation and evaluation of P2P applications based on ideas such as multi-agent and evolutionary programming borrowed from CAS. An Anthill system consists of a dynamic network of peer nodes; societies of adaptive agents travel through this network, interacting with nodes and cooperating with other agents in order to solve complex problems. Anthill can be used to construct different classes of P2P services that exhibit resilience, adaptation and self-organization properties. We also describe preliminary experiences with Anthill in implementing a file sharing application.

Messor: load-balancing through a swarm of autonomous agents

Peer-to-peer (P2P) systems are characterized by decentralized control, large-scale and extreme dynamism of their environment. Developing applications that can cope with these characteristics requires a paradigm shift that puts adaptation, resilience and self-organization as primary concerns. Complex adaptive systems (CAS), commonly used to explain the behavior of many biological and social systems, could be an appropriate response to these requirements. In order to pursue these ideas, this paper presents Messor, a decentralized load-balancing algorithm based on techniques such as multi-agent systems drawn from CAS. A novel P2P grid computing system has been designed using the Messor algorithm, allowing arbitrary users to initiate computational tasks.

Ant system for service deployment in private and public clouds

Large-scale computing platforms that serve thousands or even millions of users through the Internet are on a path to become a pervasive technology available to companies of all sizes. However, existing technologies to enable this kind of scaling are based on a hierarchically managed approach that does not scale equally well. Moreover, existing systems are also not equipped to handle the dynamism that may emerge as a result of severe failures or load surges. In this paper, we conjecture that using self-organizing techniques for system (re)configuration can improve both the scalability properties of such systems as well as their ability to tolerate churn. Specifically, the paper focuses on deployment of virtual machine images onto physical machines that reside in different parts of the network. The objective is to construct balanced and dependable deployment configurations that are resilient. To accomplish this, a method based on a variant of Ant Colony Optimization is used to find efficient deployment mappings for a large number of virtual machine image replicas that are deployed concurrently. The method is completely decentralized; ants communicate indirectly through pheromone tables located in the nodes. An example scenario is presented and simulation results are obtained for the method.

Toward self-organizing, self-repairing and resilient distributed systems

As access to networked applications become omnipresent through PC’s, hand-held and wireless devices, an increasing number of interactions in our day-to-day life with significant economical, social and cultural consequences depend on the reliability, availability and security of distributed systems. Not surprisingly, the increased demand that is being placed by users on networked services can only be met by distributed infrastructures with greater complexity and larger scale.And the extreme dynamism that is often present in different forms in modern systems further aggravates our ability to reason formally about their behavior.

Towards a Plug and Play Architecture for Telecommunications

This paper presents an architecture specified within the project “Plug-and-play for Network and Teleservice Components” supported by The Norwegian Research Council. The hardware and software parts, as well as complete network elements that constitute a communication system, shall have the ability to configure themselves when installed into a network and then to provide services according to their own capabilities, the service repertoire and the operating policies of the system.

Towards upgrading actively replicated servers on-the-fly

Change management is indispensable in most distributed software systems, which are continuously being modified throughout their life cycle. Managing the changes at runtime in highly available distributed systems is especially challenging as upgrade of a running system should not deteriorate its availability characteristics. We present a distributed algorithm that allows one to dynamically upgrade an actively replicated server so that the server is operational, even during the upgrade process. The algorithm makes use of the core functionality of an underlying group communication system that has been extended with a recovery mechanism. Its design enables dependable upgrades of replicated software in the presence of replica crashes. The presented mechanisms are part of the dynamic upgrade management framework aiming at supporting and managing dependable upgrades of distributed systems on the fly.

SenseWrap: A service oriented middleware with sensor virtualization and self-configuration

This paper presents the design and implementation of a simple and elegant middleware architecture providing virtual sensors as representatives for any type of physical sensors. With our middleware, clients can seamlessly discover sensor-hosted services through Zeroconf and it provides a standardized communication interface that applications can use without having to deal with sensor-specific details. The limited capabilities of most types of sensors prevent the inclusion of a full communication stack with IP addressing. Yet, through the use of virtual sensors, a uniform communication interface based on UDP/TCP sockets can be exposed to clients. This will significantly simplify application development for integrated services involving multiple types of sensors. Our benchmarks shows that our middleware scales well beyond the requirements of a private smart home.

Towards Adaptive, Resilient and Self-organizing Peer-to-Peer Systems

Peer-to-peer (P2P) systems are characterized by decentralized control, large scale and extreme dynamism of their operating environment. Developing applications that can cope with these characteristics requires a paradigm shift, placing adaptation, resilience and self-organization as primary concerns. In this note, we argue that complex adaptive systems (CAS), which have been used to explain certain biological, social and economical phenomena, can be the basis of a programming paradigm for P2P applications. In order to pursue this idea, we are developing Anthill, a framework to support the design, implementation and evaluation of P2P applications based on ideas such as multi-agent and evolutionary programming borrowed from CAS.

Testing robot controllers using constraint programming and continuous integration

Abstract Context Testing complex industrial robots (CIRs) requires testing several interacting control systems. This is challenging, especially for robots performing process-intensive tasks such as painting or gluing, since their dedicated process control systems can be loosely coupled with the robot’s motion control. Objective Current practices for validating CIRs involve manual test case design and execution. To reduce testing costs and improve quality assurance, a trend is to automate the generation of test cases. Our work aims to define a cost-effective automated testing technique to validate CIR control systems in an industrial context. Method This paper reports on a methodology, developed at ABB Robotics in collaboration with SIMULA, for the fully automated testing of CIRs control systems. Our approach draws on continuous integration principles and well-established constraint-based testing techniques. It is based on a novel constraint-based model for automatically generating test sequences where test sequences are both generated and executed as part of a continuous integration process. Results By performing a detailed analysis of experimental results over a simplified version of our constraint model, we determine the most appropriate parameterization of the operational version of the constraint model. This version is now being deployed at ABB Robotics’s CIR testing facilities and used on a permanent basis. This paper presents the empirical results obtained when automatically generating test sequences for CIRs at ABB Robotics. In a real industrial setting, the results show that our methodology is not only able to detect reintroduced known faults, but also to spot completely new faults. Conclusion Our empirical evaluation shows that constraint-based testing is appropriate for automatically generating test sequences for CIRs and can be faithfully deployed in an industrial context.

An approach to experimentally obtain service dependability characteristics of the Jgroup/ARM system

Jgroup/ARM is a middleware framework for operating dependable distributed applications based on Java. Jgroup integrates the distributed object models of Java RMI and Jini with the object group communication paradigm, enabling the construction of groups of replicated server objects that provide dependable services to clients. ARM provides automated mechanisms for distributing replicas to host processors and recovering from replica failures. This paper describes an approach based on stratified sampling combined with fault injections for estimating the dependability attributes of a service deployed using the Jgroup/ARM middleware framework. A first experimental evaluation is performed focusing on a service provided by a triplicated server, and indicative predictions of various dependability attributes of the service are obtained. The evaluation shows that a very high availability and MTBF may be achieved for services based on Jgroup/ARM.