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.

The concept of a Web service, as defined by W3C (World Wide Web Consortium), represents a distributed component using XML messaging. Compositions of Web services are increasingly used to create new IT capabilities fast and flexibly, in an ad hoc manner. This work extends the W3C concept of a Web service in two ways. First, we enable a Web service to offer several variations of service and QoS. In other words, we add the concept of classes of service for Web services. This widens the usability of a particular Web service. Second, we explore dynamic (i.e., run-time) adaptation and management based on the manipulation of classes of service. Our dynamic adaptation mechanisms include switching, deactivation/reactivation, and creation of classes of service. Management and dynamic adaptation of Web service compositions further improve the overall flexibility and adaptability of IT systems using Web services.

The management of mobile agent systems that solve problems in a network is an issue that must be addressed if mobile agents are to be deployed industrially. It is clear that insufficient or excessive numbers of agents can cause the problem solving capabilities of an agent-based system to be impaired. Also, agents being software entities are almost always flawed therefore requiring the upgrade problem to be solved. This paper presents distributed algorithms based upon ant social behaviour that solve the problems of agent density maintenance and the agent upgrade problem.

The creation of composite services from service components at runtime can be achieved using several different techniques. In the first approach, a new common interface is constructed at runtime which allows the functionality of two or more components to be accessed from a single entity while the service components themselves remain distinct and potentially distributed within in a network. In the second approach, a new composite service is formed where all of the functionality of the service components is housed within a single new service. In the third approach, a new composite service is formed where all the functionality of the service components is extracted and re-assembled into the body of a single new service. The paper describes the design of an infrastructure to support the runtime creation of composite services. An application to create user-defined security associations dynamically and deploy them between any two points in the Internet is presented to exemplify the need for dynamic service composition techniques. Some other potential applications in e-commerce and software provisioning are also discussed.

The computer communications world is very dynamic, requiring continual software updating for correction, perfection, and increased functionality. The problem addressed here is that of providing an evolutionary path for software that permits updating without disrupting the operation and management of the network. This problem is relevant to network management software which is also dynamic. For example SNMPv3 is not yet a standard and is not yet widely deployed. Its initial installations will need to be perfected as more experience is acquired. This paper examines a software hot-swapping solution to the problem, whereby management system software modules can be replaced dynamically without disrupting the management process. The paper also discusses application of the technique to a modular SNMPv3 system implemented in Java.

The intelligent network (IN) represents the world-wide accepted basis for uniform provisioning of advanced telecommunication services. On the other hand IP-based communication is fast becoming a viable alternative for voice communications. Mobile agents offer unique opportunities for structuring and implementing open distributed service architectures, facilitated by the dynamic downloading and movement of service code to specific network nodes. In this paper, a new service architecture for IP telephony, based on the ITU-T standard H.323, is proposed. The implementation uses mobile agents and Jini as enabling technologies and existing architectural concepts taken from IN. This IP service architecture enables telecommunication services deployed through mobile service agents on a per-user basis, which results in several advantages when compared to centralized service architectures. The paper demonstrates that the flexible extensible architecture can accommodate not only existing services but is flexible enough to accommodate a wide variety of future services. In addition we show how the architecture addresses the full management life cycle of advanced services, from open third party creation, to subscription and utilization, and ultimately to maintenance and withdrawal.

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.

Configuring a network service is not an easy task due to the manual schemes that are deployed currently. This paper proposes a plug-and-play approach for service configuration and demonstrates its workability through various distributed computing technologies.

We present an application-oriented taxonomy of mobile code. We use a novel approach to managing telecommunication networks as a vehicle for describing the concepts through demonstrating the use of several types of mobile code in innovative network and system management applications. To make a clear distinction between the types of mobile code, we use a terminology that follows the Java conventions originated with the term applet. Therefore, in our jargon, we have servlets, exflets, deglets and netlets. We point to a piglet as a type of mobile code that constitutes a security risk to the network. We deliberately avoided the term agent in our taxonomy. In this paper, this term is used to refer to a general concept of code autonomy. Our approach to managing networks addresses the issues in traditional client/server, or in this context manager/agent, network management systems like the amount of data that needs to be transmitted, problems inherent to heterogeneous environment, like interoperability issues, problems with maintainability of the software, etc. With the techniques based on mobile code, we can harness many interoperability issues and work toward plug-and-play networks (PnPnets) by applying mobile agents that can take care of many aspects of configuring and maintaining networks in an autonomous way.

The research thrust of the Perpetuum project is the use of mobile intelligent agents for network management. Mobile agents are migratory programs that move from one host to another to access remote data and services at their location, rather than transporting the data to a central location. The use of mobile agents affords new opportunities for the distribution of processing and control in network management due to their autonomous and cooperative nature. We envision a network manager as a suite of problem-specific applications that launch and/or communicate with autonomous mobile network agents that we call netlets. The intent is to provide an extensible set of tools that shift the operator's focus from MIB browsing to problem-solving. In this poster, we demonstrate this shift by applying mobile agents to network modeling. Instead of regarding the network model as the repository of the network topology, a network model is defined as an application-oriented view of the network. Depending on the application, the view will not only be defined in terms of a set of static components, but also in terms of the dynamic status of these components. The mobile agent implementation of a network model browser is explained, followed by an exploration of innovative extensions that transform this model discovery tool into a problem-browser.

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. That's 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.

This paper describes a new diagnostic method and its application to communications network fault diagnosis. This new method uses belief propagation to accumulate evidence which it then uses for diagnosis. It has been successfully applied to the accurate, real-time diagnosis of break faults in large wide area data communications networks where the normal status messages provide very uncertain evidence of a fault and its location. It was tested on simulated WANs of up to 30000 monitored devices, including tests with either SNMP/PING or OSI monitoring, and also on a simulated WAN with an ATM/B-ISDN subnetwork. It achieved 99.96% accuracy in diagnosing 2499 out of 2500 break faults, making no extra false diagnoses, even though up to 127 devices were broken at once. Operational tests and trials were also carried out over which it achieved 99% accuracy. On both simulated and real networks it required approximately 1% of the CPU of a SUN SPARC 2 for every 15000 network devices monitored. It is now in operation in the network operations centre of a large, corporate WAN.>

The authors discuss the role of an expert system for monitoring troubles in a wide-area network of circuit-switching, private, automatic computer exchanges embedded in a wide-area computer network (WAN). They present a taxonomy of diagnostic problems based on the breadth of view of the network necessary to detect and diagnose them and a further taxonomy of the types of patterns of events which must be detected. The architecture and experimental development of an expert monitor for a single exchange within such a network is presented with some emphasis on a design approach for eventual real-time implementation.>

In this paper, a variable-frame hybrid multiplexer with a min-max constraint on frame length is proposed. Using a single server queueing model, it is shown that the performance of the variableframe multiplexer with respect to channel utilization, blocking, and delay is better than its fixed frame counterpart. Some of the results are compared to those from earlier studies.

In this correspondence we complement, by means of an analytical model, an earlier simulation study on tradeoff between delay and TASI advantage in a packetized speech multiplexer.

When terminals (data and/or voice), connected to an asynchronous time division multiplexer (ATDM), are buffered and operate at low speed, the arrivals at the multiplexer are correlated. In this paper, we consider the finite buffer behavior of an ATDM with such terminals. An earlier study by Rudin [6] is a special case of this approach. The treatment here is also an improvement over the analysis by Birdsall et al. [1] of an ATDM with speech sources and is suitable for packet voice applications.

This paper develops algorithms for verifying pointer values in DBTG (Data Base Task Group) type databases. To validate pointer implemented access paths and set structures, two algorithms are developed. The first procedure exploits the “typed pointer” concept employed in modern programming languages to diagnose abnormalities in directories and set instances. The second algorithm completes pointer validation by examining set instances to ensure that each DBTG set has a unique owner. Sequential processing is used by both algorithms, allowing a straightforward implementation which is efficient in both time and space. As presented, the algorithms are independent of implementation schema and physical structure.