Policy-based approaches to the management of systems distinguish between the specification of requirements, in the form of policies, and their enforcement on the system. In this work we focus on the latter aspect and investigate the enforcement of stateful policies in a concurrent environment. As a representative of stateful policies we use the UCON model and show how dependencies between policy rules affect their enforcement. We propose a technique for enforcing policies concurrently based on the static analysis of dependencies between policies. The potential of our technique for improving the efficacy of enforcement mechanisms is illustrated using a small, but representative example.

Policies provide a flexible and scalable approach to the management of distributed systems by separating the specification of security requirements and their enforcement Over the years the expressiveness of policy languages increased considerably making it possible to capture a variety of complex requirements that for example depend on the history of the system execution. The most important criteria for the successful operation of policy-managed systems is whether the deployed enforcement mechanisms can guarantee the compliance with the policies. With the expressiveness of policy languages this assurance is increasingly difficult to achieve. In this paper we therefore address the development of enforcement mechanisms from a theoretical perspective and show how enforcement code can be formally derived for compositional, history-dependent policies that can change dynamically over time or on the occurrence of events.

The use of cloud computing (CC) is rapidly increasing due to the demand for internet services and communications. The large number of services and data stored in the cloud creates security risks due to the dynamic movement of data, connected devices and users between various cloud environments. In this study, we will develop an innovative prototype for location-aware access control and data privacy for CC systems. We will apply location-aware access control policies to role-based access control of Cloud Foundry, and then analyze the impact on user privacy after implementing these policies. This innovation can be used to address the security risks introduced by inter-cloud use and communication, and will have significant impact in making citizen's personal data more secure.

The quality of execution tracing impacts the time to a great extent to locate errors in software components; moreover, execution tracing is the most suitable tool, in the majority of the cases, for doing postmortem analysis of failures in the field. Nevertheless, software product quality models do not adequately consider execution tracing quality at present neither do they define the quality properties of this important entity in an acceptable manner. Defining these quality properties would be the first step towards creating a quality model for execution tracing. The current research fills this gap by identifying and defining the variables, i.e., the quality properties, on the basis of which the quality of execution tracing can be judged. The present study analyses the experiences of software professionals in focus groups at multinational companies, and also scrutinises the literature to elicit the mentioned quality properties. Moreover, the present study also contributes to knowledge with the combination of methods while computing the saturation point for determining the number of the necessary focus groups. Furthermore, to pay special attention to validity, in addition to the the indicators of qualitative research: credibility, transferability, dependability, and confirmability, the authors also considered content, construct, internal and external validity.