The role of the RM-ODP computational viewpoint concepts in the MDA approach

An MDA design approach should be able to accommodate designs at different levels of platform-independence. We have proposed a design approach previously (in [2]), which allows these levels to be identified. An important feature of this approach is the notion of abstract platform. An abstract platform is determined by the platform characteristics that are relevant for applications at a certain level of platform-independence, and must be established by considering various design goals. In this paper, we define a framework that makes it possible to use RM-ODP concepts in our MDA design approach. This framework allows a recursive application of the computational viewpoint at different levels of platform-independence. This is obtained by equating the RM-ODP notion of infrastructure to our notion of abstract platform

Protocols versus objects: can models for telecommunications and distributed processing coexist?

This paper identifies two paradigms that influence the design of telematics systems nowadays: the protocol-centred and the object-centred paradigms. Both paradigms have been introduced to cope with interoperability, each in their own way. The coexistence of these paradigms can have an enormous impact on the design of telematics systems. This paper identifies some combined uses of both paradigms and some fundamental research problems related to the coexistence of these paradigm

Developing frameworks for protocol implementation

This paper presents a method to develop frameworks for protocol implementation. Frameworks are software structures developed for a specific application domain, which can be reused in the implementation of various different concrete systems in this domain. The use of frameworks support a protocol implementation process connected with formal design methods and produce an implementation code easy to extend and to reuse

Delivered versus Mill Nonlinear Pricing in Free Entry Markets

This paper discusses a model where consumers simultaneously differ according to one unobservable (preference for quality) and one observable characteristic (location). In these circumstances nonlinear prices arise in equilibrium. The main question addressed in this work is whether firms should be allowed to practise different nonlinear prices at each location (delivered nonlinear pricing) or should be forced to set an unique nonlinear contract (mill nonlinear pricing). Assuming that firms can costless relocate, we show that the free entry long-run number of firms may be either smaller, equal, or higher under delivered nonlinear pricing. In addition, we show that delivered nonlinear pricing yields in the long-run higher welfare and, consequently, our results support the view that discriminatory nonlinear pricing should not be prohibited.

Delivered versus Mill Nonlinear Pricing in Free Entry Markets

This paper discusses a model where consumers simultaneously differ according to one unobservable (preference for quality) and one observable characteristic (location). In these circumstances nonlinear prices arise in equilibrium. The main question addressed in this work is whether firms should be allowed to practise different nonlinear prices at each location (delivered nonlinear pricing) or should be forced to set an unique nonlinear contract (mill nonlinear pricing). Assuming that firms can costless relocate, we show that the free entry long-run number of firms may be either smaller, equal, or higher under delivered nonlinear pricing. In addition, we show that delivered nonlinear pricing yields in the long-run higher welfare and, consequently, our results support the view that discriminatory nonlinear pricing should not be prohibited.Delivered nonlinear pricing, Mill nonlinear pricing, Asymmetric information, Pricing regulation

An Analysis of Service Ontologies

Services are increasingly shaping the world’s economic activity. Service provision and consumption have been profiting from advances in ICT, but the decentralization and heterogeneity of the involved service entities still pose engineering challenges. One of these challenges is to achieve semantic interoperability among these autonomous entities. Semantic web technology aims at addressing this challenge on a large scale, and has matured over the last years. This is evident from the various efforts reported in the literature in which service knowledge is represented in terms of ontologies developed either in individual research projects or in standardization bodies. This paper aims at analyzing the most relevant service ontologies available today for their suitability to cope with the service semantic interoperability challenge. We take the vision of the Internet of Services (IoS) as our motivation to identify the requirements for service ontologies. We adopt a formal approach to ontology design and evaluation in our analysis. We start by defining informal competency questions derived from a motivating scenario, and we identify relevant concepts and properties in service ontologies that match the formal ontological representation of these questions. We analyze the service ontologies with our concepts and questions, so that each ontology is positioned and evaluated according to its utility. The gaps we identify as the result of our analysis provide an indication of open challenges and future work

Design of a shared whiteboard component for multimedia conferencing

This paper reports on the development of a framework for multimedia applications in the domain of tele-education. The paper focuses on the protocol design of a specific component of the framework, namely a shared whiteboard application. The relationship of this component with other components of the framework is also discussed. A salient feature of the framework is that it uses an advanced ATM-based network service. The design of the shared whiteboard component is considered representative for the design as a whole, and is used to illustrate how a flexible protocol architecture utilizing innovative network functions and satisfying demanding user requirements can be developed

Towards a Unifying Process Framework for Services Knowledge Management

Activities concerned with the design, planning and execution of services are becoming increasingly complex. This is due to the involvement of many different stakeholders, the complexity of the service systems themselves, and the dynamic nature of their organizational and ICT environments. Service knowledge management helps share and reuse relevant knowledge among the different stakeholders, and therefore emerges as a critical factor to perform service activities with required efficiency and quality. Recent advances in knowledge management provide promising opportunities to support individual service activities within a single domain. Yet, sharing knowledge throughout the service life-cycle and across service domains is still very challenging. The source of service knowledge, its usage, update frequency, encoding and associated stakeholders may vary depending upon the service activity and the service domain. Based on a critical analysis of currently proposed frameworks, we argue that a process framework approach is beneficial for service knowledge management. To support our claim, we offer an abstract template and a typical service life-cycle that can be adopted to integrate heterogeneous service knowledge from diverse sources

A Framework for the Evaluation of Semantics-based Service Composition Approaches

The benefits of service composition are being largely acknowledged in the literature nowadays. However, as the amount of available services increases, it becomes difficult to manage, discover, select and compose them, so that automation is required in these processes. This can be achieved by using semantic information represented in ontologies. Currently there are many different approaches that support semantics-based service composition. However, still little effort has been spent on creating a common methodology to evaluate and compare such approaches. In this paper we present our initial ideas to create an evaluation framework for semantics-based service composition approaches. We use a collection of existing services, and define a set of evaluation metrics, confusion matrix-based and time-based. Furthermore, we present how composition evaluation scenarios are generated from the collection of services and specify the strategy to be used in the evaluation process. We demonstrate the proposed framework through an example. Currently there are mechanisms and initiatives to address the evaluation of the semantics-based service discovery and matchmaking approaches. However, still few efforts have been spent on the creation of comprehensive evaluation mechanisms for semantics-based service composition approaches