Dynamic Model-based Management of Service-Oriented Infrastructure.

Models are an effective tool for systems and software design. They allow software architects to abstract from the non-relevant details. Those qualities are also useful for the technical management of networks, systems and software, such as those that compose service oriented architectures. Models can provide a set of well-defined abstractions over the distributed heterogeneous service infrastructure that enable its automated management. We propose to use the managed system as a source of dynamically generated runtime models, and decompose management processes into a composition of model transformations. We have created an autonomic service deployment and configuration architecture that obtains, analyzes, and transforms system models to apply the required actions, while being oblivious to the low-level details. An instrumentation layer automatically builds these models and interprets the planned management actions to the system. We illustrate these concepts with a distributed service update operation

The Value Added Tax: Its Causes and Consequences

Almost unknown in 1960, the value added tax (VAT) is now found in more than 130 countries, raises around 20 percent of the world’s tax revenue, and has been the centerpiece of tax reform in many developing countries. This paper explores the causes and consequences of the remarkable rise of the VAT. A key question is whether it has indeed proved, as its proponents claim, an especially effective form of taxation. To address this, it is first shown that a tax innovation—such as the introduction of a VAT—reduces the marginal cost of public funds if and only if it also leads an optimizing government to increase the tax ratio. This observation leads to the estimation, on a panel of 143 countries for 25 years, of a system of equations describing both the probability of VAT adoption and the revenue impact of the VAT. The results point to a rich set of determinants of VAT adoption, this being more likely, for example, if a country has a program with the IMF and the less open it is to international trade. In the revenue equation, the presence of a VAT does indeed have a significant impact, but also a complex one, with a negative intercept effect counteracted by positive effects that are greater the higher are per capita income and, more tentatively, openness. While the sign of the revenue impact of the VAT is thus in general ambiguous, most countries that have adopted a VAT seem to have gained a more effective tax instrument in doing so (though this is less apparent in sub-Saharan Africa), and most without it seem likely to gain from its adoption.Value added tax; tax reform

The Value Added Tax : Its Causes and Consequences

Almost unknown in 1960, the value added tax (VAT) is now found in more than 130 countries, raises around 20 percent of the world’s tax revenue, and has been the centerpiece of tax reform in many developing countries. This paper explores the causes and consequences of the remarkable rise of the VAT. A key question is whether it has indeed proved, as its proponents claim, an especially effective form of taxation. To address this, it is first shown that a tax innovation—such as the introduction of a VAT—reduces the marginal cost of public funds if and only if it also leads an optimizing government to increase the tax ratio. This observation leads to the estimation, on a panel of 143 countries for 25 years, of a system of equations describing both the probability of VAT adoption and the revenue impact of the VAT. The results point to a rich set of determinants of VAT adoption, this being more likely, for example, if a country has a program with the IMF and the less open it is to international trade. In the revenue equation, the presence of a VAT does indeed have a significant impact, but also a complex one, with a negative intercept effect counteracted by positive effects that are greater the higher are per capita income and, more tentatively, openness. While the sign of the revenue impact of the VAT is thus in general ambiguous, most countries that have adopted a VAT seem to have gained a more effective tax instrument in doing so (though this is less apparent in sub-Saharan Africa), and most without it seem likely to gain from its adoption.Value added tax ; tax reform

Deliverable JRA1.1: Evaluation of current network control and management planes for multi-domain network infrastructure

This deliverable includes a compilation and evaluation of available control and management architectures and protocols applicable to a multilayer infrastructure in a multi-domain Virtual Network environment.The scope of this deliverable is mainly focused on the virtualisation of the resources within a network and at processing nodes. The virtualization of the FEDERICA infrastructure allows the provisioning of its available resources to users by means of FEDERICA slices. A slice is seen by the user as a real physical network under his/her domain, however it maps to a logical partition (a virtual instance) of the physical FEDERICA resources. A slice is built to exhibit to the highest degree all the principles applicable to a physical network (isolation, reproducibility, manageability, ...). Currently, there are no standard definitions available for network virtualization or its associated architectures. Therefore, this deliverable proposes the Virtual Network layer architecture and evaluates a set of Management- and Control Planes that can be used for the partitioning and virtualization of the FEDERICA network resources. This evaluation has been performed taking into account an initial set of FEDERICA requirements; a possible extension of the selected tools will be evaluated in future deliverables. The studies described in this deliverable define the virtual architecture of the FEDERICA infrastructure. During this activity, the need has been recognised to establish a new set of basic definitions (taxonomy) for the building blocks that compose the so-called slice, i.e. the virtual network instantiation (which is virtual with regard to the abstracted view made of the building blocks of the FEDERICA infrastructure) and its architectural plane representation. These definitions will be established as a common nomenclature for the FEDERICA project. Other important aspects when defining a new architecture are the user requirements. It is crucial that the resulting architecture fits the demands that users may have. Since this deliverable has been produced at the same time as the contact process with users, made by the project activities related to the Use Case definitions, JRA1 has proposed a set of basic Use Cases to be considered as starting point for its internal studies. When researchers want to experiment with their developments, they need not only network resources on their slices, but also a slice of the processing resources. These processing slice resources are understood as virtual machine instances that users can use to make them behave as software routers or end nodes, on which to download the software protocols or applications they have produced and want to assess in a realistic environment. Hence, this deliverable also studies the APIs of several virtual machine management software products in order to identify which best suits FEDERICA’s needs.Postprint (published version

Distributed Access Control for Web and Business Processes

Middleware influenced the research community in developing a number of systems for controlling access to distributed resources. Nowadays a new paradigm for the lightweight integration of business resources from different partners is starting to take hold – Web Services and Business Processes for Web Services. Security and access control policies for Web Services protocols and distributed systems are well studied and almost standardized, but there is not yet a comprehensive proposal for an access control architecture for business processes. So, it is worth looking at the available approaches to distributed authorization as a starting point for a better understanding of what they already have and what they still need to address the security challenges for business processes

On Engineering Support for Business Process Modelling and Redesign

Currently, there is an enormous (research) interest in business process redesign (BPR). Several management-oriented approaches have been proposed showing how to make BPR work. However, detailed descriptions of empirical experience are few. Consistent engineering methodologies to aid and guide a BPR-practitioner are currently emerging. Often, these methodologies are claimed to be developed for business process modelling, but stem directly from information system design cultures. We consider an engineering methodology for BPR to consist of modelling concepts, their representation, computerized tools and methods, and pragmatic skills and guidelines for off-line modelling, communicating, analyzing, (re)designing\ud business processes. The modelling concepts form the architectural basis of such an engineering methodology. Therefore, the choice, understanding and precise definition of these concepts determine the productivity and effectiveness of modelling tasks within a BPR project. The\ud current paper contributes to engineering support for BPR. We work out general issues that play a role in the development of engineering support for BPR. Furthermore, we introduce an architectural framework for business process modelling and redesign. This framework consists of a coherent set of modelling concepts and techniques on how to use them. The framework enables the modelling of both the structural and dynamic characteristics of business processes. We illustrate its applicability by modelling a case from service industry. Moreover, the architectural framework supports abstraction and refinement techniques. The use of these techniques for a BPR trajectory are discussed

Formalisation and Implementation of the XACML Access Control Mechanism

We propose a formal account of XACML, an OASIS standard adhering to the Policy Based Access Control model for the specifica- tion and enforcement of access control policies. To clarify all ambiguous and intricate aspects of XACML, we provide it with a more manageable alternative syntax and with a solid semantic ground. This lays the basis for developing tools and methodologies which allow software engineers to easily and precisely regulate access to resources using policies. To demonstrate feasibility and effectiveness of our approach, we provide a software tool, supporting the specification and evaluation of policies and access requests, whose implementation fully relies on our formal development