Bernard Pagurek

Mobile agents for network management

In this article we discuss the potential uses of mobile agents in network management and define software agents and a navigation model that determines agent mobility. We list a number of potential advantages and disadvantages of mobile agents and include a short commentary on the ongoing standardization activity. The core of this article comprises descriptions of several actual and potential applications of mobile agents in the five OSI functional areas of network management. A brief review of other research activity in the area and prospects for the future conclude the presentation.

Management applications of the web service offerings language (WSOL)

We discuss Web Service Management (WSM) and Web Service Composition Management (WSCM) applications of the Web Service Offerings Language (WSOL) and how the language supports these applications. WSOL is a language for the formal specification of classes of service, various constraints (functional constraints, Quality of Service QoS, and access rights), and management statements (prices, monetary penalties, and management responsibilities) for Web Services. Describing a Web Service in WSOL, in addition to the Web Services Description Language, enables monitoring, metering, accounting, and management of Web Services. Metering of QoS metrics and evaluation of constraints can be the responsibility of the provider Web Service, the consumer, and/or one or more mutually trusted third parties (SOAP intermediaries or probes). Further, manipulation (switching, deactivation, reactivation, deletion, or creation) of classes of service can be used for dynamic (run-time) adaptation and management of Web Service compositions. To demonstrate the usefulness of WSOL for WSM and WSCM, we have developed a corresponding management infrastructure, the Web Service Offerings Infrastructure (WSOI). WSOI enables monitoring of WSOL-enabled Web Services and dynamic manipulation of their classes of service.

WSOL - Web Service Offerings Language

WSOL (Web Service Offerings Language) is an XML (Extensible Markup Language) notation compatible with the WSDL (Web Services Description Language) standard. While WSDL is used for describing operations provided by Web Services, WSOL enables formal specification of multiple classes of service for one Web Service. A service offering is a formal representation of one class of service for a Web Service. As classes of service for Web Services are determined by combinations of various constraints, WSOL enables formal specification of functional constraints, some QoS (a.k.a., non-functional) constraints, simple access rights (for differentiation of service), price, and relationships with other service offerings of the same Web Service. Describing a Web Service in WSOL, in addition to WSDL, enables selection of a more appropriate Web Service and service offering for particular circumstances. Further, it supports dynamic adaptation and management of Web Service compositions using manipulation of service offerings.

Towards multi-swarm problem solving in networks

This paper describes how multiple interacting swarms of adaptive mobile agents can be used to solve problems in networks. The paper introduces a new architectural description for an agent that is chemically inspired and proposes chemical interaction as the principal mechanism for inter-swarm communication. Agents within a given swarm have behavior that is inspired by the foraging activities of ants, with each agent capable of simple actions and knowledge of a global goal is not assumed. The creation of chemical trails is proposed as the primary mechanism used in distributed problem solving arising from self-organization of swarms of agents. The paper proposes that swarm chemistries can be engineered in order to apply the principal ideas of the Subsumption Architecture in the domain of mobile agents. The paper presents applications of the new architecture in the domain of communications networks and describes the essential elements of a mobile agent framework that is being considered for its implementation.

The conjugate gradient method for optimal control problems with bounded control variables

This paper applies directly the method of conjugate gradients in function space to the iterative solution of optimal control problems in which the control variables must satisfy inequality constraints. Two different conjugate gradient algorithms and their modifications to include bounded control variables are considered. The results of applying the method to several examples, one of which contains a region of singular optimal control, are included.

Infrastructure for advanced network management based on mobile code

The research is part of the Perpetuum project that makes use of mobile agents for network management. In this paper, we introduce an infrastructure that is required for a new approach to network management utilizing mobile code. This involves providing a framework for code mobility, access to managed resources and communication between agents. The infrastructure is the fundamental part that provides the base upon which our research of applications of mobile code technology is built. The infrastructure is built on Java. Java addresses several critical issues, such as security, portability, persistent state through serialization, networking, and other features. Thats why Java was selected for the development of the infrastructure. We also present some examples of infrastructure application to demonstrate the advantages of the use of mobile agents for network management.

Integration of mobile agents with SNMP: why and how

Mobile agents have been proposed as a solution to the problem of the management of increasingly heterogeneous networks. However, the proposed solutions often ignore the value of legacy solutions and protocols. This paper extends an existing mobile agent framework targeted at network management with an architecture and design for integration with an SNMP agent. Brief descriptions of the use of this solution for the provisioning of ATM permanent virtual circuits and providing a mobile agent MIB are also provided.

On Requirements for Ontologies in Management of Web Services

Formal specification of various constraints, including quality of service (QoS) and price, is very important for successful dynamic (i.e., runtime) composition of Web Services. For specification of these constraints, it is important to formally define QoS metrics, measurement units, and currency units used. Ontologies provide a mechanism for such formal definition. In this paper we discuss some requirements for ontologies that can be used in representing QoS constraints and in management of Web Services, with special focus on QoS metrics, measurement units, and currency units. Particularly, we emphasize the need for the formal representation of dependencies and relationships between QoS metrics, even when such information seems redundant. Our study of existing ontologies showed that they need further work to satisfy our requirements. We also state the need for independent, third-party Web Services for ontological translations between different QoS metrics, measurement units, and currencies.

Web Service Offerings Infrastructure (WSOI) - a management infrastructure for XML Web services

Our Web Service Offerings Language (WSOL) enables formal specification of important management information - classes of service (modeled as service offerings), various types of constraint (functional, QoS, access rights), and management statements (e.g., prices, penalties, and management responsibilities) - for XML (Extensible Markup Language) Web services. To demonstrate the usefulness of WSOL for the management of Web services and their compositions, we have developed a corresponding management infrastructure, the Web Service Offerings Infrastructure (WSOI). WSOI enables monitoring and accounting of WSOL service offerings and their dynamic manipulation. To support monitoring of WSOL service offerings, we have extended the Apache Axis open-source SOAP engine with WSOI-specific modules, data structures, and management ports. To support dynamic manipulation of WSOL service offerings, we have developed appropriate algorithms, protocols, and management port types and built into WSOI modules and data structures for their implementation. Apart from provisioning of WSOL-enabled Web services, we are using WSOI to perform experiments comparing dynamic manipulation of WSOL service offerings and alternatives.

Distributed fault location in networks using mobile agents

This paper describes how multiple interacting swarms of adaptive mobile agents can be used to locate faults in networks. The paper proposes the use of distributed problem solving using mobile agents for fault finding in order to address the issues of client/server approaches to network management and control, such as scalability and the difficulties associated with maintaining an accurate view of the network. The paper uses a recently described architectural description for an agent that is biologically inspired and proposes chemical interaction as the principal mechanism for inter-swarm communication. Agents have behavior that is inspired by the foraging activities of ants, with each agent capable of simple actions; global knowledge is not assumed. The creation of chemical trails is proposed as the primary mechanism used in distributed problem solving arising from the self-organization of swarms of agents. Fault location is achieved as a consequence of agents moving through the network, sensing, acting upon sensed information, and subsequently modifying the chemical environment that they inhabit. Elements of a mobile code framework that is being used to support this research, and the mechanisms used for agent mobility within the network environment, are described.