Enterprises increasingly recognize the compelling economic and operational benefits from virtualizing and pooling IT resources in the cloud. Nevertheless, the significant and valuable transformation of organizations that adopt cloud computing is accompanied by a number of security threats that should be considered. In this paper, we outline significant security challenges presented when migrating to a cloud environment and propose PaaSword – a novel holistic framework that aspires to alleviate these challenges. Specifically, the proposed framework involves a context-aware security model, the necessary policies enforcement mechanism along with a physical distribution, encryption and query middleware.

It is generally conceded that, due to security and privacy concerns, enterprises and users are reluctant to embrace the cloud computing paradigm and hence benefit from the cost reductions and the increased flexibility or business agility that this paradigm brings about. These concerns stem mainly from the significantly-expanded attack surfaces that result from the heterogeneous nature of cloud services and the dynamicity inherent in cloud environments. In order to alleviate these concerns, effective and flexible access control approaches are required to consider the contextual parameters that characterise data access requests in the cloud. In this respect, this work presents PaaSword: a novel holistic access control framework-essentially a PaaS offering-that extends the popular XACML standard with semantic reasoning capabilities that support the federation of effective context-aware access control policies and their infusion into cloud applications with minimal manual intervention and effort. To determine the performance of our solution, a comparative evaluation test is presented and discussed, against a well-known reference implementation of the XACML standard, namely the open source WSO2 Balana engine.

Enterprises are embracing cloud computing in order to reduce costs and increase agility in their everyday business operations. Nevertheless, due mainly to confidentiality, privacy and integrity concerns, many are still reluctant to migrate their sensitive data to the cloud. In this paper, firstly, we outline the construction of a suitable Context-aware Security Model, for enhancing security in cloud applications. Secondly, we outline the construction of an extensible and declarative formalism for representing policy-related knowledge, one which disentangles the definition of a policy from the code employed for enforcing it. Both of them will be employed for supporting innovative PaaS-enabled access control mechanisms.

This paper reports a sub-set of findings from an in-depth study of Greek university teachers' conceptions of, and approaches to, the use of virtual learning environments (VLEs) in teaching. A central strand of the study is an exploration of factors influencing the development of networked learning in Greek higher education (HE) through a qualitative examination of the pedagogical perspectives that teachers bring to bear on their use of new information and communication technologies (ICTs: in this case, specifically VLEs such as WebCT, Blackboard or Moodle). The project is investigating the relationship between Greek university teachers' conceptions of teaching using VLEs and current theoretical perspectives of relevance to the e-learning field, in particular those perspectives that are associated with the principles and practices of networked learning as a distinctive form of e-learning. The paper presents preliminary findings from this strand in the light of previous research into teachers' conceptions of teaching and use of VLEs. A phenomenographic research approach has been adopted for this study. Phenomenography is an interpretive approach that seeks to identify the range of variation in ways of perceiving or experiencing a phenomenon of interest in this case the way in which Greek university teachers understand the educational use of VLEs. For the pilot study, the sample included five computer science academics from three universities in Greece. The interviews concentrated on seeking variations in pedagogical purposes in using VLEs for teaching and learning, and in approaches to their use Analysis of the open-ended interviews revealed three qualitatively different conceptions of teaching using VLEs, and different pedagogical approaches associated with them. The 'information transfer' conception was associated with information- (or content) - oriented pedagogical approaches to using VLEs. 'Understanding concepts' and 'developing concepts' conceptions were associated with more activity- (or process-) oriented approaches. The data suggest that there may be a relationship between the subject being taught (within the broad discipline of computer science) and different conceptions and approaches to using VLEs. Although based on a very small sample, the pilot study also suggests that pedagogical conceptions and approaches associated with networked learning may not be widely prevalent in computer science teaching in Greece